C# if else

Summary: in this tutorial, you’ll learn how to use the C# if else statement to execute a block when a condition is true and another block otherwise.

Introduction to the C# if else statement

In practice, you often want to execute a block when a condition is true and execute another block otherwise. In this case, you need to use the if else statement.

The following illustrates the syntax of the if else statement:

if (condition)
{
    // if statements
}
else
{
    // else statements
}Code language: C# (cs)

In this syntax, the if else statement evaluates the condition. If the condition is true, it’ll execute the if block. Otherwise, the if else statement executes the else block.

The following flowchart illustrates how the if else statement works:

C# if else statement examples

Let’s take some examples of using the if else statement.

1) Simple C# if else statement examples

The following example uses the if else statement to show a message when the condition is "sunny":

string condition = "sunny";

if (condition == "sunny")
{
    Console.WriteLine("Let's go outside.");
}
else
{
    Console.WriteLine("Just stay home.");
}Code language: C# (cs)

Output:

Let's go outside.Code language: C# (cs)

In this example, the condition is "sunny". Therefore, you’ll see the message "Let's go outside." in the output.

The following example changes the condition to "rainy":

string condition = "rainy";

if (condition == "sunny")
{
    Console.WriteLine("Let's go outside.");
}
else
{
    Console.WriteLine("Just stay home.");
}Code language: C# (cs)

Output:

Just stay home.Code language: C# (cs)

Since the expression condition == "sunny" is false, the else block executes that shows the message "Just stay home." to the output.

2) Using if else statement with a complex condition example

The following example uses the if else statement with a complex condition:

string condition = "sunny";
bool free = true;

if (free & condition == "sunny")
{
    Console.WriteLine("Let's go outside.");
}
else
{
    Console.WriteLine("Just stay home.");
}Code language: C# (cs)

Output:

Let's go outside.Code language: C# (cs)

In this example, the condition is "sunny" and the free is true.

Because the following expression evaluates to true:`

free & condition == "sunny"Code language: C# (cs)

the if block executes to show the message "Let's go outside." to the output.

If you change the condition and/or free variables to something else that causes the expression evaluates to false, the else block will execute. For example:

string condition = "sunny";
bool free = false;

if (free & condition == "sunny")
{
    Console.WriteLine("Let's go outside.");
}
else
{
    Console.WriteLine("Just stay home.");
}Code language: C# (cs)

Output:

Just stay home.Code language: C# (cs)

Summary

• Use the C# if else statement to execute a block when a condition is true and another block otherwise.