The if statement is used to control the flow of code execution
based on the evalution of an expression. The if can take the following
forms:
if ( Expression ) StatementIfExpressionTrue
if ( Expression ) StatementIfExpressionTrue else StatementIfExpressionFalse
For instance
int x = 5; // declare a integer initialised to 5
if ( x > 4) // if x is greater then 4
x = x + 5; // add 5 to it.
if ( x < 10) // if x is less then 10
x = x +4; // add 4 to it
else // otherwise
x = x - 2; // subtract 2 from it
if ( x == 20) // if x is equal to 20
{
x=5; // set x equal to 5
x=x * 2; // set x equal to x times 2
}
if (x <= 23 ) //if x is less then or equal to 23
{
x = 0; // set x equal to 0
x = x +1; // add 1 to x
}
else // otherwise
{
x=5; // set x equal to 5
x=0; // set x equal to 0
}
if statements can also be nested. For example:
int y = 7; // declare an integer an initilize to 7
if ( y > 5 ) // if y is greater then 5
if ( y < 8) // if y is less then 8
y = 0; // set y = 0
