{"id":3242,"date":"2021-12-04T02:15:54","date_gmt":"2021-12-04T02:15:54","guid":{"rendered":"https:\/\/www.pythontutorial.net\/?page_id=3242"},"modified":"2025-03-30T08:21:50","modified_gmt":"2025-03-30T08:21:50","slug":"python-f-strings","status":"publish","type":"page","link":"https:\/\/www.pythontutorial.net\/python-basics\/python-f-strings\/","title":{"rendered":"Python F-strings"},"content":{"rendered":"\n<p><strong>Summary<\/strong>: in this tutorial, you&#8217;ll learn about Python F-strings and how to use them to format strings and make your code more readable.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id='introduction-to-the-python-f-strings'>Introduction to the Python F-strings <a href=\"#introduction-to-the-python-f-strings\" class=\"anchor\" id=\"introduction-to-the-python-f-strings\" title=\"Anchor for Introduction to the Python F-strings\">#<\/a><\/h2>\n\n\n\n<p>Python 3.6 introduced the f-strings that allow you to format text strings faster and more elegant. The f-strings provide a way to embed <a href=\"https:\/\/www.pythontutorial.net\/python-basics\/python-variables\/\">variables<\/a> and expressions inside a string literal using a clearer syntax than the <code>format()<\/code> method. <\/p>\n\n\n\n<p>For example:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-1\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\">name = <span class=\"hljs-string\">'John'<\/span>\ns = <span class=\"hljs-string\">f'Hello, <span class=\"hljs-subst\">{name}<\/span>!'<\/span>\nprint(s)<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-1\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p><a href=\"https:\/\/www.pythontutorial.net\/playground\/?q=bmFtZSA9ICdKb2huJw0KcyA9IGYnSGVsbG8sIHtuYW1lfSEnDQpwcmludChzKQ\" target=\"_blank\" rel=\"noreferrer noopener\">Try it<\/a><\/p>\n\n\n\n<p>Output:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-2\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\">Hello, John!<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-2\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>How it works.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>First, <a href=\"https:\/\/www.pythontutorial.net\/python-basics\/python-variables\/\">define a variable<\/a> with the value <code>'John'<\/code>.<\/li>\n\n\n\n<li>Then, place the <code>name<\/code> variable inside the curly braces <code>{}<\/code> in the literal string. Note that you need to prefix the string with the letter <code>f<\/code> to indicate that it is an f-string. It&#8217;s also valid if you use the letter in uppercase (<code>F<\/code>).<\/li>\n\n\n\n<li>Third, print out the string s.<\/li>\n<\/ul>\n\n\n\n<p>It&#8217;s important to note that Python evaluates the variables and expressions in f-string at runtime. It replaces variables and expressions <code>{name}<\/code> inside an f-string with their values.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id='python-f-string-examples'>Python f-string examples <a href=\"#python-f-string-examples\" class=\"anchor\" id=\"python-f-string-examples\" title=\"Anchor for Python f-string examples\">#<\/a><\/h2>\n\n\n\n<p>The following example calls the <a href=\"https:\/\/www.pythontutorial.net\/python-string-methods\/python-string-upper\/\">upper()<\/a> method to convert the name to uppercase inside the curly braces of an f-string:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-3\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\">name = <span class=\"hljs-string\">'John'<\/span>\ns = F<span class=\"hljs-string\">'Hello, {name.upper()}!'<\/span>\nprint(s)<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-3\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p><a href=\"https:\/\/www.pythontutorial.net\/playground\/?q=bmFtZSA9ICdKb2huJw0KcyA9IEYnSGVsbG8sIHtuYW1lLnVwcGVyKCl9IScNCnByaW50KHMp\" target=\"_blank\" rel=\"noreferrer noopener\">Try it<\/a><\/p>\n\n\n\n<p>Output:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-4\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\">Hello, JOHN!<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-4\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>The following example uses multiple curly braces inside an f-string:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-5\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\">first_name = <span class=\"hljs-string\">'John'<\/span>\nlast_name = <span class=\"hljs-string\">'Doe'<\/span>\ns = F<span class=\"hljs-string\">'Hello, {first_name} {last_name}!'<\/span>\nprint(s)<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-5\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p><a href=\"https:\/\/www.pythontutorial.net\/playground\/?q=Zmlyc3RfbmFtZSA9ICdKb2huJw0KbGFzdF9uYW1lID0gJ0RvZScNCnMgPSBGJ0hlbGxvLCB7Zmlyc3RfbmFtZX0ge2xhc3RfbmFtZX0hJw0KcHJpbnQocyk\" target=\"_blank\" rel=\"noreferrer noopener\">Try it<\/a><\/p>\n\n\n\n<p>Output:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-6\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\">Hello, John Doe!<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-6\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>This example is equivalent to the above example but uses the <code><a href=\"https:\/\/www.pythontutorial.net\/python-string-methods\/python-string-join\/\">join()<\/a><\/code> method:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-7\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\">first_name = <span class=\"hljs-string\">'John'<\/span>\nlast_name = <span class=\"hljs-string\">'Doe'<\/span>\ns = F<span class=\"hljs-string\">'Hello, {\" \".join((first_name, last_name))}!'<\/span>\n\nprint(s)<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-7\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p><a href=\"https:\/\/www.pythontutorial.net\/playground\/?q=Zmlyc3RfbmFtZSA9ICdKb2huJw0KbGFzdF9uYW1lID0gJ0RvZScNCnMgPSBGJ0hlbGxvLCB7IiAiLmpvaW4oKGZpcnN0X25hbWUsIGxhc3RfbmFtZSkpfSEnDQoNCnByaW50KHMp\" target=\"_blank\" rel=\"noreferrer noopener\">Try it<\/a><\/p>\n\n\n\n<p>Output:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-8\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\">Hello, John Doe!<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-8\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<h2 class=\"wp-block-heading\" id='multiline-f-strings'>Multiline f-strings <a href=\"#multiline-f-strings\" class=\"anchor\" id=\"multiline-f-strings\" title=\"Anchor for Multiline f-strings\">#<\/a><\/h2>\n\n\n\n<p>Python allows you to have multiline f-strings. To create a multiline f-string, you place the letter <code>f<\/code> in each line. For example:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-9\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\">name = <span class=\"hljs-string\">'John'<\/span>\nwebsite = <span class=\"hljs-string\">'PythonTutorial.net'<\/span>\n\nmessage = (\n    <span class=\"hljs-string\">f'Hello <span class=\"hljs-subst\">{name}<\/span>. '<\/span>\n    <span class=\"hljs-string\">f\"You're learning Python at <span class=\"hljs-subst\">{website}<\/span>.\"<\/span> \n)\n\nprint(message)<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-9\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p><a href=\"https:\/\/www.pythontutorial.net\/playground\/?q=bmFtZSA9ICdKb2huJw0Kd2Vic2l0ZSA9ICdQeXRob25UdXRvcmlhbC5uZXQnDQoNCm1lc3NhZ2UgPSAoDQogICAgZidIZWxsbyB7bmFtZX0uICcNCiAgICBmIllvdSdyZSBsZWFybmluZyBQeXRob24gYXQge3dlYnNpdGV9LiIgDQopDQoNCnByaW50KG1lc3NhZ2Up\" target=\"_blank\" rel=\"noreferrer noopener\">Try it<\/a><\/p>\n\n\n\n<p>Output:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-10\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\">Hello John. Yo<span class=\"hljs-string\">u're learning Python on PythonTutorial.net.<\/span><\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-10\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>If you want to spread an f-string over multiple lines, you can use a <a href=\"https:\/\/www.pythontutorial.net\/python-basics\/python-backslash\/\">backslash<\/a> (\\) to escape the return character like this:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-11\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\">name = <span class=\"hljs-string\">'John'<\/span>\nwebsite = <span class=\"hljs-string\">'PythonTutorial.net'<\/span>\n\nmessage = <span class=\"hljs-string\">f'Hello <span class=\"hljs-subst\">{name}<\/span>. '<\/span> \\\n          <span class=\"hljs-string\">f\"You're learning Python at <span class=\"hljs-subst\">{website}<\/span>.\"<\/span> \n\nprint(message)<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-11\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p><a href=\"https:\/\/www.pythontutorial.net\/playground\/?q=bmFtZSA9ICdKb2huJw0Kd2Vic2l0ZSA9ICdQeXRob25UdXRvcmlhbC5uZXQnDQoNCm1lc3NhZ2UgPSBmJ0hlbGxvIHtuYW1lfS4gJyBcDQogICAgICAgICAgZiJZb3UncmUgbGVhcm5pbmcgUHl0aG9uIGF0IHt3ZWJzaXRlfS4iIA0KDQpwcmludChtZXNzYWdlKQ\" target=\"_blank\" rel=\"noreferrer noopener\">Try it<\/a><\/p>\n\n\n\n<p>The following example shows how to use triple quotes (<code>\"\"\"<\/code>) with an f-string:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-12\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\">name = <span class=\"hljs-string\">'John'<\/span>\nwebsite = <span class=\"hljs-string\">'PythonTutorial.net'<\/span>\n\nmessage = <span class=\"hljs-string\">f\"\"\"Hello <span class=\"hljs-subst\">{name}<\/span>.\nYou're learning Python at <span class=\"hljs-subst\">{website}<\/span>.\"\"\"<\/span>\n\nprint(message)<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-12\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p><a href=\"https:\/\/www.pythontutorial.net\/playground\/?q=bmFtZSA9ICdKb2huJw0Kd2Vic2l0ZSA9ICdQeXRob25UdXRvcmlhbC5uZXQnDQoNCm1lc3NhZ2UgPSBmIiIiSGVsbG8ge25hbWV9Lg0KWW91J3JlIGxlYXJuaW5nIFB5dGhvbiBhdCB7d2Vic2l0ZX0uIiIiDQoNCnByaW50KG1lc3NhZ2Up\" target=\"_blank\" rel=\"noreferrer noopener\">Try it<\/a><\/p>\n\n\n\n<p>Output:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-13\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\">Hello John.\nYo<span class=\"hljs-string\">u're learning Python at PythonTutorial.net.<\/span><\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-13\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<h2 class=\"wp-block-heading\" id='curly-braces'>Curly braces <a href=\"#curly-braces\" class=\"anchor\" id=\"curly-braces\" title=\"Anchor for Curly braces\">#<\/a><\/h2>\n\n\n\n<p>When evaluating an f-string, Python replaces double curly braces with a single curly brace. However, the doubled curly braces do not signify the start of an expression. <\/p>\n\n\n\n<p>Python will not evaluate the expression inside the double curly brace and replace the double curly braces with a single one. For example:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-14\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\">s = <span class=\"hljs-string\">f'{{1+2}}'<\/span>\nprint(s)<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-14\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p><a href=\"https:\/\/www.pythontutorial.net\/playground\/?q=cyA9IGYne3sxKzJ9fScNCnByaW50KHMp\" target=\"_blank\" rel=\"noreferrer noopener\">Try it<\/a><\/p>\n\n\n\n<p>Output:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-15\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\">{<span class=\"hljs-number\">1<\/span>+<span class=\"hljs-number\">2<\/span>}<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-15\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>The following shows an f-string with triple curly braces:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-16\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\">s = <span class=\"hljs-string\">f'{{<span class=\"hljs-subst\">{<span class=\"hljs-number\">1<\/span>+<span class=\"hljs-number\">2<\/span>}<\/span>}}'<\/span>\nprint(s)<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-16\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p><a href=\"https:\/\/www.pythontutorial.net\/playground\/?q=cyA9IGYne3t7MSsyfX19Jw0KcHJpbnQocyk\" target=\"_blank\" rel=\"noreferrer noopener\">Try it<\/a><\/p>\n\n\n\n<p>Output:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-17\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\">{<span class=\"hljs-number\">3<\/span>}<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-17\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>In this example, Python evaluates the <code>{1+2}<\/code> as an expression, which returns 3. Also, it replaces the remaining doubled curly braces with a single one.<\/p>\n\n\n\n<p>To add more curly braces to the result string, you use more than triple curly braces:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-18\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\">s = <span class=\"hljs-string\">f'{{{{1+2}}}}'<\/span>\nprint(s)<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-18\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p><a href=\"https:\/\/www.pythontutorial.net\/playground\/?q=cyA9IGYne3t7ezErMn19fX0nDQpwcmludChzKQ\" target=\"_blank\" rel=\"noreferrer noopener\">Try it<\/a><\/p>\n\n\n\n<p>Output:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-19\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\">{{<span class=\"hljs-number\">1<\/span>+<span class=\"hljs-number\">2<\/span>}}<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-19\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>In this example, Python replaces each pair of doubled curly braces with a single curly brace.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id='the-evaluation-order-of-expressions-in-python-f-strings'>The evaluation order of expressions in Python f-strings <a href=\"#the-evaluation-order-of-expressions-in-python-f-strings\" class=\"anchor\" id=\"the-evaluation-order-of-expressions-in-python-f-strings\" title=\"Anchor for The evaluation order of expressions in Python f-strings\">#<\/a><\/h2>\n\n\n\n<p>Python evaluates the expressions in an f-string in the left-to-right order. This is obvious if the expressions have side effects like the following example:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-20\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\"><span class=\"hljs-function\"><span class=\"hljs-keyword\">def<\/span> <span class=\"hljs-title\">inc<\/span><span class=\"hljs-params\">(numbers, value)<\/span>:<\/span>\n    numbers&#91;<span class=\"hljs-number\">0<\/span>] += value\n    <span class=\"hljs-keyword\">return<\/span> numbers&#91;<span class=\"hljs-number\">0<\/span>]\n\nnumbers = &#91;<span class=\"hljs-number\">0<\/span>]\n\ns = <span class=\"hljs-string\">f'<span class=\"hljs-subst\">{inc(numbers,<span class=\"hljs-number\">1<\/span>)}<\/span>,<span class=\"hljs-subst\">{inc(numbers,<span class=\"hljs-number\">2<\/span>)}<\/span>'<\/span>\nprint(s)<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-20\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p><a href=\"https:\/\/www.pythontutorial.net\/playground\/?q=ZGVmIGluYyhudW1iZXJzLCB2YWx1ZSk6DQogICAgbnVtYmVyc1swXSArPSB2YWx1ZQ0KICAgIHJldHVybiBudW1iZXJzWzBdDQoNCm51bWJlcnMgPSBbMF0NCg0KcyA9IGYne2luYyhudW1iZXJzLDEpfSx7aW5jKG51bWJlcnMsMil9Jw0KcHJpbnQocyk\" target=\"_blank\" rel=\"noreferrer noopener\">Try it<\/a><\/p>\n\n\n\n<p>Output:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-21\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\"><span class=\"hljs-number\">1<\/span>,<span class=\"hljs-number\">3<\/span><\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-21\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>In this example, the following function call increases the first number in the numbers list by one:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-22\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\">inc(numbers,<span class=\"hljs-number\">1<\/span>)<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-22\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>After this call, the <code>numbers[0]<\/code> is one. And the second call increases the first number in the numbers list by 2, which results in 3.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id='format-numbers-using-f-strings'>Format numbers using f-strings <a href=\"#format-numbers-using-f-strings\" class=\"anchor\" id=\"format-numbers-using-f-strings\" title=\"Anchor for Format numbers using f-strings\">#<\/a><\/h2>\n\n\n\n<p>The following example use a f-string to format an integer as hexadecimal:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-23\" data-shcb-language-name=\"PHP\" data-shcb-language-slug=\"php\"><span><code class=\"hljs language-php\">number = <span class=\"hljs-number\">16<\/span>\ns = f<span class=\"hljs-string\">'{number:x}'<\/span>\n<span class=\"hljs-keyword\">print<\/span>(s)  <span class=\"hljs-comment\"># 10<\/span><\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-23\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">PHP<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">php<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p><a href=\"https:\/\/www.pythontutorial.net\/playground\/?q=bnVtYmVyID0gMTYNCnMgPSBmJ3tudW1iZXI6eH0nDQpwcmludChzKSAgIyAxMA\" target=\"_blank\" rel=\"noreferrer noopener\">Try it<\/a><\/p>\n\n\n\n<p>The following example uses the f-string to format a number as a scientific notation:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-24\" data-shcb-language-name=\"PHP\" data-shcb-language-slug=\"php\"><span><code class=\"hljs language-php\">number = <span class=\"hljs-number\">0.01<\/span>\ns = f<span class=\"hljs-string\">'{number:e}'<\/span>\n<span class=\"hljs-keyword\">print<\/span>(s)  <span class=\"hljs-comment\"># 1.000000e-02<\/span><\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-24\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">PHP<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">php<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p><a href=\"https:\/\/www.pythontutorial.net\/playground\/?q=bnVtYmVyID0gMC4wMQ0KcyA9IGYne251bWJlcjplfScNCnByaW50KHMpICAjIDEuMDAwMDAwZS0wMg\" target=\"_blank\" rel=\"noreferrer noopener\">Try it<\/a><\/p>\n\n\n\n<p>If you want to pad zeros at the beginning of the number, you use the f-string format as follows:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-25\" data-shcb-language-name=\"PHP\" data-shcb-language-slug=\"php\"><span><code class=\"hljs language-php\">number = <span class=\"hljs-number\">200<\/span>\ns = f<span class=\"hljs-string\">'{number: 06}'<\/span>\n<span class=\"hljs-keyword\">print<\/span>(s)  <span class=\"hljs-comment\"># 00200<\/span><\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-25\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">PHP<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">php<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p><a href=\"https:\/\/www.pythontutorial.net\/playground\/?q=bnVtYmVyID0gMjAwDQpzID0gZid7bnVtYmVyOiAwNn0nDQpwcmludChzKSAgIyAwMDIwMA\" target=\"_blank\" rel=\"noreferrer noopener\">Try it<\/a><\/p>\n\n\n\n<p>The 06 is the total number of the result numeric string including the leading zeros.<\/p>\n\n\n\n<p>To specify the number of decimal places, you can also use the f-string:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-26\" data-shcb-language-name=\"PHP\" data-shcb-language-slug=\"php\"><span><code class=\"hljs language-php\">number = <span class=\"hljs-number\">9.98567<\/span>\ns = f<span class=\"hljs-string\">'{number: .2f}'<\/span>\n<span class=\"hljs-keyword\">print<\/span>(s)  <span class=\"hljs-comment\"># 9.99<\/span><\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-26\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">PHP<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">php<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p><a href=\"https:\/\/www.pythontutorial.net\/playground\/?q=bnVtYmVyID0gOS45ODU2Nw0KcyA9IGYne251bWJlcjogLjJmfScNCnByaW50KHMpICAjIDkuOTk\" target=\"_blank\" rel=\"noreferrer noopener\">Try it<\/a><\/p>\n\n\n\n<p>Note that the f-string also performs rounding in this case.<\/p>\n\n\n\n<p>If the number is too large, you can use the number separator to make it easier to read:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-27\" data-shcb-language-name=\"PHP\" data-shcb-language-slug=\"php\"><span><code class=\"hljs language-php\">number = <span class=\"hljs-number\">400000000000<\/span>\ns = f<span class=\"hljs-string\">'{number: ,}'<\/span>  <span class=\"hljs-comment\"># also can use _<\/span>\n<span class=\"hljs-keyword\">print<\/span>(s)  <span class=\"hljs-comment\"># 400,000,000,000<\/span><\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-27\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">PHP<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">php<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p><a href=\"https:\/\/www.pythontutorial.net\/playground\/?q=bnVtYmVyID0gNDAwMDAwMDAwMDAwDQpzID0gZid7bnVtYmVyOiAsfScgICMgYWxzbyBjYW4gdXNlIF8NCnByaW50KHMpICAjIDQwMCwwMDAsMDAwLDAwMA\" target=\"_blank\" rel=\"noreferrer noopener\">Try it<\/a><\/p>\n\n\n\n<p>To format a number as a percentage, you use the following f-string format:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-28\" data-shcb-language-name=\"PHP\" data-shcb-language-slug=\"php\"><span><code class=\"hljs language-php\">number = <span class=\"hljs-number\">0.1259<\/span>\ns = f<span class=\"hljs-string\">'{number: .2%}'<\/span>\n<span class=\"hljs-keyword\">print<\/span>(s)  <span class=\"hljs-comment\"># 12.59%<\/span>\n\ns = f<span class=\"hljs-string\">'{number: .1%}'<\/span>\n<span class=\"hljs-keyword\">print<\/span>(s)  <span class=\"hljs-comment\"># 12.5%<\/span><\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-28\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">PHP<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">php<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p><a href=\"https:\/\/www.pythontutorial.net\/playground\/?q=bnVtYmVyID0gMC4xMjU5DQpzID0gZid7bnVtYmVyOiAuMiV9Jw0KcHJpbnQocykgICMgMTIuNTklDQoNCnMgPSBmJ3tudW1iZXI6IC4xJX0nDQpwcmludChzKSAgIyAxMi41JQ\" target=\"_blank\" rel=\"noreferrer noopener\">Try it<\/a><\/p>\n\n\n\n<p>Python has more <a href=\"https:\/\/docs.python.org\/3\/library\/string.html#format-specification-mini-language\" target=\"_blank\" rel=\"noreferrer noopener\">sophisticated format rules that you can reference via the following link<\/a>.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id='summary'>Summary <a href=\"#summary\" class=\"anchor\" id=\"summary\" title=\"Anchor for Summary\">#<\/a><\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Python f-strings provide an elegant way to format text strings.<\/li>\n\n\n\n<li>Python replaces the result of an expression embedded inside the curly braces <code>{}<\/code> in an f-string at runtime.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\" id='quiz'>Quiz <a href=\"#quiz\" class=\"anchor\" id=\"quiz\" title=\"Anchor for Quiz\">#<\/a><\/h2>\n\n\n\n<iframe loading=\"lazy\"\n  name=\"quiz\"\n  src=\"\/quiz\/?quiz=f-string\"\n  height=\"700\"\n  width=\"600\"\n  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