{"id":237,"date":"2022-01-01T12:40:12","date_gmt":"2022-01-01T05:40:12","guid":{"rendered":"https:\/\/csharptutorial.net\/?page_id=237"},"modified":"2022-06-03T13:27:40","modified_gmt":"2022-06-03T06:27:40","slug":"csharp-array","status":"publish","type":"page","link":"https:\/\/www.csharptutorial.net\/csharp-tutorial\/csharp-array\/","title":{"rendered":"C# Array"},"content":{"rendered":"\n

Summary<\/strong>: in this tutorial, you’ll learn about the C# array and how to use it to store a fixed number of values of the same type.<\/p>\n\n\n\n

Introduction to the C# array<\/h2>\n\n\n\n

An array stores a fixed number of elements of the same type. To declare an array variable, you use square brackets []<\/code> after the element’s type:<\/p>\n\n\n

type[] arrayName;<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
For example, the following declares an array of integers:<\/p>\n\n\n
int<\/span>[] scores;<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
To create an array, you use the new<\/code> keyword with the element’s type and the number of elements that the array will hold. <\/p>\n\n\n\n
For example, the following declares an array variable and creates a new array that holds five integers:<\/p>\n\n\n
int<\/span>[] scores;\nscores = new<\/span> int<\/span>[5<\/span>];<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
Also, you can both declare and create a new array using a single statement like this:<\/p>\n\n\n
int<\/span>[] scores = new<\/span> int<\/span>[5<\/span>];<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
Since we haven’t initialized the elements of the scores<\/code> array, they will take the default value of the int<\/code> type, which is zero.<\/p>\n\n\n\n
Accessing array elements<\/h2>\n\n\n\n
To access an element of an array, you use the square bracket []<\/code> with an index. An array is zero-based indexing. It means that the index of the first element starts at zero, the index of the second element starts at one, and so on. <\/p>\n\n\n\n
If an array has N elements, the index of the last element is N – 1. The following example assigns an integer to each array’s element in the scores<\/code> array:<\/p>\n\n\n
scores[0<\/span>] = 3<\/span>;\nscores[1<\/span>] = 2<\/span>;\nscores[2<\/span>] = 5<\/span>;\nscores[3<\/span>] = 4<\/span>;\nscores[4<\/span>] = 1<\/span>;<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
Initializing an array<\/h2>\n\n\n\n
To declare and populate an array in a single statement, you can use the array initialization expression. The following example defines the scores<\/code> array and initializes its elements:<\/p>\n\n\n
int<\/span>[] scores = new<\/span> int<\/span>[5<\/span>] { 3<\/span>, 2<\/span>, 5<\/span>, 4<\/span>, 1<\/span> };<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
Or simply:<\/p>\n\n\n
int<\/span>[] scores = { 3<\/span>, 2<\/span>, 5<\/span>, 4<\/span>, 1<\/span> };<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
Getting array size<\/h2>\n\n\n\n
The Length<\/code> property returns the size of an array. To access the Length<\/code> property, you use the array variable with the dot operator and Length<\/code> property. For example:<\/p>\n\n\n
scores.Length<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
Iterating over array elements<\/h2>\n\n\n\n
To iterate over elements of an array, you use the for<\/a><\/code> statement. The following example uses the for<\/code> statement to output the elements of the scores<\/code> array to the console:<\/p>\n\n\n
int<\/span>[] scores = { 3<\/span>, 2<\/span>, 5<\/span>, 4<\/span>, 1<\/span> };\n\nfor<\/span> (int<\/span> i = 0<\/span>; i < scores.Length; i++)\n{\n    Console.WriteLine(scores[i]);\n}<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
3<\/span>\n2<\/span>\n5<\/span>\n4<\/span>\n1<\/span><\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
Hence, you can define a function that outputs an array of integers to the console like this:<\/p>\n\n\n
void<\/span> PrintArray<\/span>(int<\/span>[] items<\/span>)<\/span>\n{\n    for<\/span> (int<\/span> i = 0<\/span>; i < items.Length; i++)\n    {\n        Console.Write($\"{items[i]}<\/span> \"<\/span>);\n    }\n}<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
Indices<\/h2>\n\n\n\n
Indices allow you to reference the elements relative to the end of the array with the ^<\/code> operator and an index. The ^1<\/code> references the last element, ^2<\/code> references the second-to-last element, and so on.<\/p>\n\n\n\n
The following example uses indices to access the last and the second-to-last elements of the scores<\/code> array:<\/p>\n\n\n
int<\/span>[] scores = { 3<\/span>, 2<\/span>, 5<\/span>, 4<\/span>, 1<\/span> };\n\nConsole.WriteLine(scores[^1<\/span>]); \/\/ 1<\/span>\nConsole.WriteLine(scores[^2<\/span>]); \/\/ 4<\/span><\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
1<\/span>\n4<\/span><\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
The Index<\/code> type allows you to access an array element using a variable instead of a literal integer. For example:<\/p>\n\n\n
int<\/span>[] scores = { 3<\/span>, 2<\/span>, 5<\/span>, 4<\/span>, 1<\/span> };\n\nIndex lastIndex = ^2<\/span>;\nConsole.WriteLine(scores[lastIndex]); \/\/ 4<\/span><\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
Ranges<\/h2>\n\n\n\n
Ranges allow you to slice an array using the ..<\/code> operator. <\/p>\n\n\n\n
The following returns a new array that stores the first N<\/code> elements in an array.<\/p>\n\n\n
arrayName[..N]<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
The following returns a new array that stores all the elements starting from the N<\/code> element to the end of the array:<\/p>\n\n\n
arrayName[N..]<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
The following returns a new array that stores the elements from the N<\/code> to M<\/code> element:<\/p>\n\n\n
arrayName[N..M]<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
See the following example:<\/p>\n\n\n
void<\/span> PrintArray<\/span>(int<\/span>[] items<\/span>)<\/span>\n{\n    for<\/span> (int<\/span> i = 0<\/span>; i < items.Length; i++)\n    {\n        Console.Write($\"{items[i]}<\/span> \"<\/span>);\n    }\n    Console.WriteLine();\n}\n\nint<\/span>[] scores = { 3<\/span>, 2<\/span>, 5<\/span>, 4<\/span>, 1<\/span> };\n\nConsole.WriteLine(\"scores:\"<\/span>);\nPrintArray(scores);\n\n\n\/\/ get the first two elements<\/span>\nint<\/span>[] subScores = scores[..2<\/span>];\nConsole.WriteLine(\"scores[2..]:\"<\/span>);\nPrintArray(subScores);\n\n\/\/ get the elements starting from the 3rd element<\/span>\nsubScores = scores[2.<\/span>.];\nConsole.WriteLine(\"scores[2..]:\"<\/span>);\nPrintArray(subScores);\n\n\/\/ get all the elements starting from the 2nd element<\/span>\nConsole.WriteLine(\"scores[1..3]:\"<\/span>);\nsubScores = scores[1.<\/span>.3<\/span>];\nPrintArray(subScores);<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
scores:\n3<\/span> 2<\/span> 5<\/span> 4<\/span> 1<\/span>\nscores[..2<\/span>]:\n3<\/span> 2<\/span>\nscores[2.<\/span>.]:\n5<\/span> 4<\/span> 1<\/span>\nscores[1.<\/span>.3<\/span>]:\n2<\/span> 5<\/span><\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
The Range<\/code> type allows you to slice an array using a variable. For example:<\/p>\n\n\n
void<\/span> PrintArray<\/span>(int<\/span>[] items<\/span>)<\/span>\n{\n    for<\/span> (int<\/span> i = 0<\/span>; i < items.Length; i++)\n    {\n        Console.Write($\"{items[i]}<\/span> \"<\/span>);\n    }\n    Console.WriteLine();\n}\n\nint<\/span>[] scores = { 3<\/span>, 2<\/span>, 5<\/span>, 4<\/span>, 1<\/span> };\n\nRange r = 1.<\/span>.3<\/span>;\n\nPrintArray(scores[r]);<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
Summary<\/h2>\n\n\n\n
  • An array holds a fixed number of elements of the same type.<\/li>
  • An array is a zero-based index.<\/li>
  • Use the Length<\/code> property to access the size of an array.<\/li>
  • Use the for<\/code> statement to iterate over elements of an array.<\/li>
  • Use indices (^index<\/code>) to access elements from the end of an array.<\/li>
  • Use ranges to slice an array.<\/li>
  • Do use an array if the number of elements is known at the design time. Avoid using it if the size of the array is now known.<\/li><\/ul>\n
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