C# |逐字字符串–@
在 C# 中，使用特殊符号 @ 创建逐字字符串。@被称为逐字标识符。如果字符串包含@作为前缀，后跟双引号，则编译器会将该字符串识别为逐字字符串并编译该字符串。@ symbol 的主要优点是告诉字符串构造函数忽略转义字符和换行符。@符号主要有以下三种用法:
使用 1: 关键字作为标识符 该符号允许使用关键字作为标识符。@符号作为关键字的前缀，因此编译器将关键字作为标识符，没有任何错误，如下例所示:
示例:
// C# program to illustrate
// the use of @ by using keyword
// as an identifier
using System;
public class GFG {
// Main method
static public void Main()
{
// Creating and initializing the array
// here 'for' keyword is used as
// an identifier by using @ symbol
string[] @for = {"C#", "PHP", "Java", "Python"};
// as and for keywords is
// as an identifier
// using @ symbol
foreach (string @as in @for)
{
Console.WriteLine("Element of Array: {0}", @as);
}
}
}
Output:
Element of Array: C#
Element of Array: PHP
Element of Array: Java
Element of Array: Python
使用 2: 打印字符串中的转义序列，并使用换行符等。在没有任何转义序列的字符串中。
如果将转义序列如“\ \”(用于反斜杠)、“\ u”(Unicode 转义序列)、“\ x”(十六进制转义序列)等。在不使用@符号的字符串中，编译器会自动解释这些序列。但是" "(双引号)不是字面意思。这就像一个字符串插值。让我们看看有和没有@符号的不同情况。
-
Case 1:
```cs // taking a string literal and // try to print double quotes string str1 = """";
// printing output // this will give compile // time error as Unexpected // symbol `' Console.WriteLine(str1);
```
在上面的程序中，双引号内的双引号作为字符串文字被解释为单引号。
-
Case 2:
```cs // taking a string literal prefixes // with @ and try to print double quotes string str1 = @"""";
// printing output // this will output as " Console.WriteLine(str1);
```
在上面的程序中，输出是双引号(“)而不是“
-
案例 3:
```cs // taking a string in which we are storing // some location of file but \Testing will // interpreted as eascape sequence \T // similarly \N string str1 = "\C:\Testing\New\Target";
// printing str1 // this will give compile time error as // Unrecognized escape sequence
\T' // Unrecognized escape sequence\N' // Unrecognized escape sequence `\T' Console.WriteLine(str1);```
-
案例 4:
```cs // taking a string and prefix literal with @ symbol. // Storing some location of file string str1 = @"\C:\Testing\New\Target";
// printing str1 will give output as // \C:\Testing\New\Target Console.WriteLine(str1);
```
程序:
// C# program to illustrate
// the use of @ in terms of
// escape sequences and new
// line and tab
using System;
public class GFG {
// Main method
static public void Main()
{
// If you use the below commented
// the part then this will give
// Unrecognized escape sequence error
// string S1 = "\\welcome \to GeeksforGeeks \ portal \";
// Console.WriteLine("String 1 is :{0}", S1);
// By using @ in the given string
// it runs smoothly because
// @ symbol tells the compiler to
// ignore all escape sequences
string S2 = @"\\welcome \to GeeksforGeeks \ portal \";
Console.WriteLine("String 2 is: {0}", S2);
// printing new line character in string literal
// but it will make the string to break
// into a new line, see output
string S3 = "This is \n C# non verbatim string";
Console.WriteLine("String 3 is :{0}", S3);
// By using @ symbol /n does not processed
string S4 = @"This is \n C# verbatim string";
Console.WriteLine("String 4 is :{0}", S4);
// printing a string literal contains
// tabs and new line without using
// any escape sequence
Console.WriteLine(@"Without Tab Sequence and New Line Character
C C++ Java Python");
}
}
Output:
String 2 is: \\welcome \to GeeksforGeeks \ portal \
String 3 is :This is
C# non verbatim string
String 4 is :This is \n C# verbatim string
Without Tab Sequence and New Line Character
C C++ Java Python
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