All the While

C provides a pre-test loop structure. The basic form of this statement is:

while( condition )
   statement

For example,

x = 5 ;
while( x > 0 )
   x-- ;

will count x down from 5 to 0. (Since it doesn't do anything else, these statements could be replaced by the statement, x = 0 ; and the program would function the same way.) The loop:

a = 1 ;
while( a < b )
   a *= 2 ;

is a little more useful. It finds the smallest power of two that is greater than or equal to b.

Just as for the if statement, the body of the while may be a compound statement instead of just a single statement. For example, one approach to a counted loop would look like:

i = 0 ;
while( i < 10 ) {
   printf( "%d\n", i ) ;
   i++ ;
}

This code fragment will print out the values 0 to 9.

What will y equal after this code fragmnt is executed?

y = 0 ;
x = 11 ;
while( x > y )
   y += 3 ;