(C) == operator

The equal/equality operator is used to compare two values. It is very commonly used in if-statements.

if (x==y) { /* what to do if x and y are equal  */ }
else      { /* what to do if x and y are not equal  */ }

It opposite operator is the not equal operator, !=.

The six logical-test operators are:

==, equal operator
!=, not equal operator
<, less than operator
>, greater than operator
<=, less than or equal
>=, greater than or equal

Beware of the assign operator, =:

//WRONG! USED THE ASSIGN OPERATOR
if (x=y) /* set 'x' to the value of y */
{ 
  /* What to do if x is not equal to 0 */
}
else      
{ 
  /* What to do if x is equal to 0 */
}

Some people use the notation below:

/* No typo: */
if (0==x) /* if x equals 0 */
/* Type detected by compiler: */
if (0=x) /* ERROR: Cannot change value of zero! */

because the value zero is constant.

'Equal operator' links

last edited (November 9, 2006) by bilderbikkel, Number of views: 659, Current Rev: 1

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