# Increment & Decrement Operators

#### Definition of C Increment & Decrement Operators

C also provides the unary increment operator (++), and the unary decrement operator (- -). If a variable b is to be incremented by 1, the increment operator (++) can be used rather than the expressions b = b + 1 or b += 1.

If increment or decrement operators are placed before a variable (prefixed), they’re referred to as the preincrement or predecrement operators, respectively.

If increment or decrement operators are placed after a variable (postfixed), they’re referred to as the postincrement or postdecrement operators, respectively.

The following table list the increment and decrement operators:

 Operator Sample expression Explanation ++ ++a Increment a by 1, then use the new value of a in the expression in which a resides. ++ a++ Use the current value of a in the expression in which a resides, then increment a by 1. -- --b Decrement b by 1, then use the new value of b in the expression in which b resides. -- b-- Use the current value of b in the expression in which b resides, then decrement b by 1.

The c program below demonstrates the difference between the preincrementing and the postincrementing versions of the (++) operator.

Postincrementing the variable b causes it to be incremented after it’s used in the printf statement. Preincrementing the variable b causes it to be incremented before it’s used in the printf statement.

``````
#include <stdio.h>
// function main begins program execution
int main( void )    {
int b;
b = 10;

printf( "%d\n", b ); // print 10
printf( "%d\n", b++ ); // print 10 then postincrement
printf( "%d\n\n", b ); // print 11

printf( "--------------\n" );

b = 10;
printf( "%d\n", b );  print 10
printf( "%d\n", ++b ); preincrement then print 11
printf( "%d\n", b );  print 11
return 0 ;
}  // end function main
``````
``````
Output:
10
10
11
--------------
10
11
11
```
```

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