(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
}

Note that if x is const, the compiler will detect the error. Knowing this, 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: 2495, Current Rev: 10 (Diff)

[Edit this page] [Page history] [What links here] [Discuss this topic] [Printer Friendly]