if, else (C++)
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Category
C++ Syntax
if ( <condition1> ) <statement1>
if ( <condition1> ) <statement1>; else <statement2>;
if ( <condition1> ) <statement1>; else if ( <condition2> ) <statement2>; else <statement3>;
if ( <condition1> )
{
if ( <condition2> ) {
<statement1>
<statement2>
}
else <statement3>
}
else
<statement4>
Description
Use if to implement a conditional statement.
You can declare variables in the condition expression. For example,
if (int val = func(arg))
is valid syntax. The variable val is in scope for the if statement and extends to an else block when it exists.
The condition statement must convert to a bool type. Otherwise, the condition is ill-formed.
When <condition> evaluates to true, <statement1> executes.
If <condition> is false, <statement2> executes.
The else keyword is optional, but no statements can come between an if statement and an else.
The #if and #else preprocessor statements (directives) look similar to the if and else statements, but have very different effects. They control which source file lines are compiled and which are ignored.