C# |文字
固定值称为。文字是变量使用的值。值可以是整数、浮点数或字符串等。
// Here 100 is a constant/literal.
int x = 100;
文字可以是以下类型:
*Integer text Floating-point text Character text *String text Empty text Boolean****
*整数文字:整数类型的文字称为整数文字。它可以是八进制、十进制、二进制或十六进制常量。十进制数字不需要前缀。后缀也可以与整数文字一起使用，如 U 或 u 用于无符号数字，而 l 或 L* 用于长数字。默认情况下，每个文字都是 int 类型的。对于整型数据类型(字节、短整型、整型、长整型)，我们可以通过以下方式指定文字:
*Decimal character (radix 10): In this form, the allowed number of digits is 0-9.**
int x = 101;
- Octal character (radix 8): In this form, the allowed number of digits is 0-7.
// The octal number should be prefix with 0.
int x = 0146;
- Six decimal characters (base16): In this form, the allowed numbers are 0-9 and the characters are A-F. We can use both uppercase and lowercase characters. As we know, c# is a case-sensitive programming language, but here c# is case-insensitive.
// The hexa-decimal number should be prefix
// with 0X or 0x.
int x = 0X123Face;
- Binary characters (radix 2): In this form, only of 1 and of 0 are allowed.
// The binary number should be prefix with 0b.
int x = 0b101
例:
07778 // invalid: 8 is not an octal digit
045uu // invalid: suffix (u) is repeated
0b105 // invalid: 5 is not a binary digit
0b101 // valid binary literal
456 // valid decimal literal
02453 // valid octal literal
0x65d // valid hexadecimal literal
12356 // valid int literal
304U // valid unsigned int literal
3078L // valid long literal
965UL // valid unsigned long literal
程序:
C
// C# program to illustrate the use of Integer Literals
using System;
class Geeks{
// Main method
public static void Main(String[] args)
{
// decimal-form literal
int a = 101;
// octal-form literal
int b = 0145;
// Hexa-decimal form literal
int c = 0xFace;
// binary-form literal
int x = 0b101;
Console.WriteLine(a);
Console.WriteLine(b);
Console.WriteLine(c);
Console.WriteLine(x);
}
}
101
145
64206
5
浮点文字:具有整数部分、小数点、小数部分和指数部分的文字称为浮点文字。这些可以用十进制或指数形式表示。
例:
Double d = 3.14145 // Valid
Double d = 312569E-5 // Valid
Double d = 125E // invalid: Incomplete exponent
Double d = 784f // valid
Double d = .e45 // invalid: missing integer or fraction
程序:
c
// C# program to illustrate the use of
// floating-point literals
using System;
class Geeks {
// Main Method
public static void Main(String[] args)
{
// decimal-form literal
double a = 101.230;
// It also acts as decimal literal
double b = 0123.222;
Console.WriteLine(a);
Console.WriteLine(b);
}
}
输出:
101.23
123.222
注意:默认情况下，每个浮点文字都是双精度类型，因此我们不能直接赋值给浮点变量。但是我们可以通过以 f 或 f 为后缀将浮点文字指定为浮点类型，我们可以通过以 D 或 D 为后缀将浮点文字明确指定为双精度类型，当然，这种约定不是必需的。
字符文字:对于字符数据类型，我们可以通过 3 种方式指定文字:
- Single quotation mark: We can specify the text as the character data type within the single quotation mark.
char ch = 'a';
- Unicode representation: We can specify the character' \ uxxxx' in the Unicode representation. Xxxx here represents four hexadecimal numbers.
char ch = '\u0061';// Here /u0061 represent a.
- Escape sequence: Each escape character can be designated as a character literal.
char ch = '\n';
例:
c
// C# program to illustrate the use of char literals
using System;
class Geeks {
// Main Method
public static void Main(String[] args)
{
// character literal within single quote
char ch = 'a';
// Unicode representation
char c = '\u0061';
Console.WriteLine(ch);
Console.WriteLine(c);
// Escape character literal
Console.WriteLine("Hello\n\nGeeks\t!");
}
}
a
a
Hello
Geeks !
字符串文字:包含在双引号(" "中或以 @"" 开头的文字称为字符串文字。
例:
String s1 = "Hello Geeks!";
String s2 = @"Hello Geeks!";
程序:
c
// C# program to illustrate the use of String literals
using System;
class Geeks {
// Main Method
public static void Main(String[] args)
{
String s = "Hello Geeks!";
String s2 = @"Hello Geeks!";
// If we assign without "" then it
// treats as a variable
// and causes compiler error
// String s1 = Geeks;
Console.WriteLine(s);
Console.WriteLine(s2);
}
}
输出:
Hello Geeks!
Hello Geeks!
布尔文字:布尔文字只允许有两个值，即真和假。
例:
bool b = true;
bool c = false;
程序:
c
// C# program to illustrate the use
// of boolean literals
using System;
class Geeks {
// Main Method
public static void Main(String[] args)
{
bool b = true;
bool c = false;
// these will give compile time error
// bool d = 0;
// bool e = 1;
// Console.WriteLine(d);
// Console.WriteLine(e);
Console.WriteLine(b);
Console.WriteLine(c);
}
}
输出:
```cs True False
```**
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