📜  C#– if else语句

📅  最后修改于: 2021-05-29 18:40:05             🧑  作者: Mango

在C#中,我们知道如果条件为true,则执行if语句,否则它将不会执行。但是,如果条件为假,我们想打印/执行某些操作,该怎么办。这里谈到的else语句。如果给定条件为假,则将其他语句与if语句一起使用以执行一些代码块。换句话说,在if-else语句中,如果给定条件的值为true,则执行if条件,或者如果给定条件的值为false,则执行else条件。

  • 其他语句可以包含一个或多个 大括号{}中的语句。如果else语句仅包含 单个语句,则括号是可选的。
  • 其他语句语句可以是任何类型/类型的像它可能包含另一个if-else语句

句法:

if(condition)
{  
    // code if condition is true  
}
else
{  
    // code if condition is false  
}  

流程图:

如果在C#中使用其他语句

范例1:

C#
// C# program to demonstrate
// if-else statement
using System;
  
class GFG{
      
static public void Main()
{
      
    // Declaring and initializing variables
    string x = "Geeks";
    string y = "GeeksforGeeks";
      
    // If-else statement
    if (x == y)
    {
        Console.WriteLine("Both strings are equal..!!");
    }
      
    // else statement
   else
    {
         Console.WriteLine("Both strings are not equal..!!");
    }
}
}


C#
// C# program to demonstrate if-else statement
using System;
  
class GFG{
      
static public void Main()
{
      
    // Declaring and initializing variables
    int x = 10;
    int y = 100;
      
    // If-else statement
    if (x >= y)
    {
        Console.WriteLine("x is greater than y");
    }
      
    // else statement
   else
    {
         Console.WriteLine("x is not greater than y");
    }
}
}


C#
// C# program to demonstrate short-hand 
// of if-else statement
using System;
  
class GFG{
      
static public void Main()
{
      
    // Declaring and initializing variables
    string x = "Geeks";
    string y = "GeeksforGeeks";
      
    // Short-hand if-else statement
    string result = (x == y) ? "Both strings are equal" : "Not equal";
      
    // Display result
    Console.WriteLine(result);
}
}


C#
// C# program to demonstrate nested 
// Ternary Operator
using System; 
  
class GFG{ 
      
static void Main(string[] args) 
{ 
      
  int a = 23, b = 90;
    
  string result = a > b ? "a is greater than b" : 
                  a < b ? "a is less than b" :
                  a == b ? "a is equal to b" : "Invalid";
          
  Console.WriteLine(result);
} 
}


输出:

Both strings are not equal..!!

范例2:

C#

// C# program to demonstrate if-else statement
using System;
  
class GFG{
      
static public void Main()
{
      
    // Declaring and initializing variables
    int x = 10;
    int y = 100;
      
    // If-else statement
    if (x >= y)
    {
        Console.WriteLine("x is greater than y");
    }
      
    // else statement
   else
    {
         Console.WriteLine("x is not greater than y");
    }
}
}

输出:

x is not greater than y

if-else语句的简写

C#还提供了if-else语句的简便实现,该语句也称为三元运算符(?:),因为它包含三个操作数。它基本上用于用单行替换多行代码。根据布尔表达式的值,它将返回两个值之一。

句法:

variable_name = (condition) ? TrueExpression :  FalseExpression;

在这里,如果给定条件为true,则将执行TrueExpression语句。或者,如果给定条件为false,则将执行FalseExpression语句。

注意: C#还支持嵌套三元运算符。

范例1:

C#

// C# program to demonstrate short-hand 
// of if-else statement
using System;
  
class GFG{
      
static public void Main()
{
      
    // Declaring and initializing variables
    string x = "Geeks";
    string y = "GeeksforGeeks";
      
    // Short-hand if-else statement
    string result = (x == y) ? "Both strings are equal" : "Not equal";
      
    // Display result
    Console.WriteLine(result);
}
}

输出:

Not equal

范例2:

C#

// C# program to demonstrate nested 
// Ternary Operator
using System; 
  
class GFG{ 
      
static void Main(string[] args) 
{ 
      
  int a = 23, b = 90;
    
  string result = a > b ? "a is greater than b" : 
                  a < b ? "a is less than b" :
                  a == b ? "a is equal to b" : "Invalid";
          
  Console.WriteLine(result);
} 
}

输出:

a is less than b