C# – if Statement

In C#, if statement is used to indicate which statement will execute according to the value of the given boolean expression. When the value of the boolean expression is true, then the if statement will execute the given then statement, otherwise it will return the control to the next statement after the if statement. 

• In C#, you are allowed to use if statement with then statement or with else statement according to your requirement.
• Then statement contains single or multiple statements and these statements are enclosed in curly braces({}). For a single statement, braces can be optional, if the curly brackets {} are not used with if statements, then the statement just next to it is only considered associated with the if statement.
• Then statement can be of any kind/type like it may contain another if-else statement.

Syntax:

if(condition)
{
    then statement;
}

Flow Chart: 

Let us discuss if statements with the help of the given examples:

Example 1:

C#

// C# program to demonstrate
// if statement
using System;

class GFG{

static public void Main()
{

    // Declaring and initializing variables
    string x = "GeeksforGeeks";
    string y = "GeeksforGeeks";

    // If statement
    if (x == y)
    {
        Console.WriteLine("Both strings are equal..!!");
    }

    // If statement
    if (x != y)
    {
         Console.WriteLine("Both strings are not equal..!!");
    }
}
}

Output:

Both strings are equal..!!

Explanation: In the above example, we have two strings, i.e., x and y. Now in the first, if statement, we compare string x to string y and the result of the comparison is true. So, the then block executes and prints “Both strings are equal..!! “. Now in the second if statement, we check both strings are not equal, but the strings are equal, so the then block of this if statement will not execute.

Example 2:

C#

// C# program to demonstrate nested
// if statement
using System;

class GFG{
static public void Main()
{

    // Declaring and initializing variables
    string emp_name = "Rohit";
    int salary = 10000;

    // If statement
    // Here if condition checks
    // the employee name is equal to rohit
    if (emp_name == "Rohit")
    {

        // Nested if statement
        // Here if the salary of Rohit
        // is greater than 50000 then
        // he is eligible to pay tax
        // Otherwise not eligible
        if (salary > 50000)
        {
            Console.WriteLine("Eligible to pay tax");
        }
        else
        {
            Console.WriteLine("Not Eligible");
        }
    }
}
}

Output:

Not Eligible

Example 3:

C#

// C# program to illustrate if statement
// Using AND, OR, NOT operators
using System;

class GFG{

static public void Main()
{

    // Declaring and initializing variables
    int x1 = 15;
    int x2 = 18;
    int x3 = 20;

    // If statement
    // Using AND operator
    if (x1 > 20 && x2 > 20)
    {
        Console.WriteLine("Enter group A");
    }

    // If statement
    // Using OR operator
    if (x1 < 30 || x3 == 20)
    {
        Console.WriteLine("Enter group B");
    }

    // If statement
    // Using NOT operator
    if (!(x1 > 20 && x2 > 20))
    {
        Console.WriteLine("Enter group C");
    }
}
}

Output:

Enter group B
Enter group C