The relational operators are used to determine whether two numbers are equal, or if one is greater or less than the other. Every relationa...
The relational operators are used to determine whether two numbers are equal, or if one is greater or less than the other. Every relational statement evaluates to either 1 (TRUE) or 0 (FALSE). The relational operators are presented later, in Table 4.1.
If the integer variable myAge has the value 39, and the integer variable yourAge has the value 40, you can determine whether they are equal by using the relational "equals" operator:
myAge == yourAge; // is the value in myAge the same as in yourAge?
This expression evaluates to 0, or false, because the variables are not equal. The expression
myAge > yourAge; // is myAge greater than yourAge?
evaluates to 0 or false.
WARNING: Many novice C++ programmers confuse the assignment operator (=) with the equals operator (==). This can create a nasty bug in your program.
There are six relational operators: equals (==), less than (<), greater than (>), less than or equal to (<=), greater than or equal to (>=), and not equals (!=). Table 4.1 shows each relational operator, its use, and a sample code use.
Table 4.1. The Relational Operators.
| Name | Operator | Sample | Evaluates |
| Equals | == | 100 == 50; | false |
| 50 == 50; | true | ||
| Not Equals | != | 100 != 50; | true |
| 50 != 50; | false | ||
| Greater Than | > | 100 > 50; | true |
| 50 > 50; | false | ||
| Greater Than | >= | 100 >= 50; | true |
| or Equals | 50 >= 50; | true | |
| Less Than | < | 100 < 50; | false |
| 50 < 50; | false | ||
| Less Than | <= | 100 <= 50; | false |
| or Equals | 50 <= 50; | true |
DO remember that relational operators return the value 1 (true) or 0 (false). DON'T confuse the assignment operator (=) with the equals relational operator (==). This is one of the most common C++ programming mistakes--be on guard for it.
