The increment & Decrement Operators (++ & --)

C uses another operator that is not common in other languages: the increment operator. Consider the following program:


included files
void main()
{
 int num=0;
 clrscr();
 printf("Number=%d",num);
 printf("\nNumber=%d",num++);
 printf("\nNumber=%d",num);
 getch();
}


The output of the program will be:


   Number=0
   Number=0
   Number=1


How did the variable num get to be 1? As you can guess by examination of the program, the (++) operator had the effect of incrementing num; that is , adding 1 to it. The first printf() statement printed the original value of num, which was 0, The second printf() also printed the original value of num; then, after num was printed, the (++) operator incremented it. Thus the third printf() statement printed out the incremented value. The effect of num(++) is exactly the same as that of the statement
   num=num+1;
However, num(++) is far compact to write.


Since there's an increment operator you can guess there will be a decrement operator as well. Let's modify the above program, using (--), the decrement operator:


included files
void main()
{
 int num=0;
 clrscr();
 printf("Number=%d",num);
 printf("\nNumber=%d",num--);
 printf("\nNumber=%d",num);
 getch();
} 


The output will be:


   Number=0
   Number=0
   Number=-1


The effect is just the same as executing the statement
   num=num-1;


The (++) and (--) operators can increment and decrement a variable without the need for a separate program statement.






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