C Sharp Programming/Keywords/if
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The if keyword identifies an if statement with the following syntax:
- if-statement ::= "
if" "(" condition ")" if-body ["else" else-body] - condition ::= boolean-expression
- if-body ::= statement-or-statement-block
- else-body ::= statement-or-statement-block
If the condition evaluates to true, the if-body executes. Curly braces ("{" and "}") allow the if-body to contain more than one statement. Optionally, an else clause can immediately follow the if-body, providing code to execute when the condition is false. Making the else-body another if statement creates the common cascade of if, else if, else if, else if, else statements:
using System;
public class IfStatementSample
{
public void IfMyNumberIs()
{
int myNumber = 5;
if ( myNumber == 4 )
Console.WriteLine("This will not be shown because myNumber is not 4.");
else if( myNumber < 0 )
{
Console.WriteLine("This will not be shown because myNumber is not negative.");
}
else if( myNumber % 2 == 0 )
Console.WriteLine("This will not be shown because myNumber is not even.");
else
{
Console.WriteLine("myNumber does not match the coded conditions, so this sentence will be shown!");
}
}
}
The boolean expression used in an if statement typically contains one or more of the following operators:
| Operator | Meaning |
|---|---|
| < | less than |
| > | greater than |
| <= | less than or equal to |
| >= | greater than or equal to |
| == | equal to |
| != | not equal to |
| && | and |
| || | or |
| ! | not |
See also else.
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| Special C# Identifiers | ||||||||||
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