{"id":87,"date":"2020-10-03T01:22:02","date_gmt":"2020-10-03T01:22:02","guid":{"rendered":"https:\/\/www.pythontutorial.net\/?page_id=87"},"modified":"2025-03-26T10:19:10","modified_gmt":"2025-03-26T10:19:10","slug":"python-if","status":"publish","type":"page","link":"https:\/\/www.pythontutorial.net\/python-basics\/python-if\/","title":{"rendered":"Python if Statement"},"content":{"rendered":"\n

Summary<\/strong>: in this tutorial, you’ll learn how to use the Python if<\/code> statement to execute a block of code based on a condition.<\/p>\n\n\n\n

The simple Python if statement #<\/a><\/h2>\n\n\n\n

You use the if <\/code>statement to execute a block of code based on a specified condition. <\/p>\n\n\n\n

The syntax of the if <\/code>statement is as follows:<\/p>\n\n\n

if<\/span> condition:\n    if<\/span>-block<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
The if<\/code> statement checks the condition first.<\/p>\n\n\n\n
If the condition evaluates to True<\/code>, it executes the statements in the if-block. Otherwise, it ignores the statements.<\/p>\n\n\n\n
Note that the colon (:<\/code>) that follows the condition<\/code> is very important. If you forget it, you’ll get a syntax error.<\/p>\n\n\n\n
The following flowchart illustrates the if statement:<\/p>\n\n\n
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\"\"<\/figure>\n<\/div>\n\n\n
For example:<\/p>\n\n\n
age = input('Enter your age:'<\/span>)\nif<\/span> int(age) >= 18<\/span>:\n    print(\"You're eligible to vote.\"<\/span>)<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
This example prompts you to input your age. If you enter a number that is greater than or equal to 18<\/code>, it’ll show a message \"You're eligible to vote\"<\/code> on the screen. Otherwise, it does nothing.<\/p>\n\n\n\n
The condition int(age) >= 18<\/code> converts the input string to an integer and compares it with 18.<\/p>\n\n\n
Enter your age:18<\/span>\nYou're eligible to vote.<\/span><\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
See the following example:<\/p>\n\n\n
age = input('Enter your age:'<\/span>)\nif<\/span> int(age) >= 18<\/span>:\n    print(\"You're eligible to vote.\"<\/span>)\n    print(\"Let's go and vote.\"<\/span>)<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
In this example, if you enter a number that is greater than or equal to 18<\/code>, you’ll see two messages.<\/p>\n\n\n\n
In this example, indentation is very important. Any statement that follows the if<\/code> statement needs to have four spaces.<\/p>\n\n\n\n
If you don’t use the indentation correctly, the program will work differently. For example:<\/p>\n\n\n
age = input('Enter your age:'<\/span>)\nif<\/span> int(age) >= 18<\/span>:\n    print(\"You're eligible to vote.\"<\/span>)\nprint(\"Let's go and vote.\"<\/span>)<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
In this example, the final statement always executes regardless of the condition<\/code> in the if<\/code> statement. The reason is that it doesn’t belong to the if<\/code> block:<\/p>\n\n\n
Enter your age:11<\/span>\nLet's go and vote.<\/span><\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Python if…else statement #<\/a><\/h2>\n\n\n\n
Typically, you want to perform an action when a condition is True<\/code> and another action when the condition is False<\/code>.<\/p>\n\n\n\n
To do so, you use the if...else<\/code> statement. <\/p>\n\n\n\n
The following shows the syntax of the if...else<\/code> statement:<\/p>\n\n\n
if<\/span> condition:\n    if<\/span>-block;\nelse<\/span>:\n    else<\/span>-block;<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
In this syntax, the if...else<\/code> will execute the if-block<\/code> if the condition evaluates to True<\/code>. Otherwise, it’ll execute the else-block<\/code>.<\/p>\n\n\n\n
The following flowchart illustrates the if..else<\/code> statement:<\/p>\n\n\n
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\"\"<\/figure>\n<\/div>\n\n\n
The following example illustrates you how to use the  if...else<\/code> statement:<\/p>\n\n\n
age = input('Enter your age:'<\/span>)\nif<\/span> int(age) >= 18<\/span>:\n    print(\"You're eligible to vote.\"<\/span>)\nelse<\/span>:\n    print(\"You're not eligible to vote.\"<\/span>)<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
In this example, if you enter your age with a number less than 18, you’ll see the message \"You're not eligible to vote.\"<\/code> like this:<\/p>\n\n\n
Enter your age:11<\/span>\nYou're not eligible to vote.<\/span><\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Python if…elif…else statement #<\/a><\/h2>\n\n\n\n
If you want to check multiple conditions and perform an action accordingly, you can use the if...elif...else<\/code> statement. The elif<\/code> stands for else if<\/code>.<\/p>\n\n\n\n
Here is the syntax if the if...elif...else<\/code> statement:<\/p>\n\n\n
if<\/span> if<\/span>-condition:\n    if<\/span>-block\nelif<\/span> elif<\/span>-condition1:\n    elif<\/span>-block1\nelif<\/span> elif<\/span>-condition2:\n    elif<\/span>-block2\n...\nelse<\/span>:\n    else<\/span>-block<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
The if...elif...else<\/code> statement checks each condition (if-condition<\/code>, elif-condition1<\/code>, elif-condition2<\/code>, …) in the order that they appear in the statement until it finds the one that evaluates to True<\/code>.<\/p>\n\n\n\n
When the if...elif...else<\/code> statement finds one, it executes the statement that follows the condition and skips testing the remaining conditions.<\/p>\n\n\n\n
If no condition evaluates to True<\/code>, the if...elif...else<\/code> statement executes the statement in the else<\/code> branch.<\/p>\n\n\n\n
Note that the else<\/code> block is optional. If you omit it and no condition is True<\/code>, the statement does nothing.<\/p>\n\n\n\n
The following flowchart illustrates the if...elif...else<\/code> statement:<\/p>\n\n\n\n
\"\"<\/figure>\n\n\n\n
The following example uses the if...elif..else<\/code> statement to determine the ticket price based on the age:<\/p>\n\n\n
age = input('Enter your age:'<\/span>)\n\n# convert the string to int<\/span>\nyour_age = int(age)\n\n# determine the ticket price<\/span>\nif<\/span> your_age < 5<\/span>:\n    ticket_price = 5<\/span>\nelif<\/span> your_age < 16<\/span>:\n    ticket_price = 10<\/span>\nelse<\/span>:\n    ticket_price = 18<\/span>\n\n# show the ticket price<\/span>\nprint(f\"You'll pay ${ticket_price}<\/span> for the ticket\"<\/span>)\n<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
In this example: <\/p>\n\n\n\n
Try it<\/a><\/p>\n\n\n\n
Try it<\/a><\/p>\n\n\n\n
Try it<\/a><\/p>\n\n\n\n
Try it<\/a><\/p>\n\n\n\n
Try it<\/a><\/p>\n\n\n\n