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Increment and decrement operators in C

In the next program

     main()
 {
     int a = 21;
     int b = 10;
     int c ;
     c = a++; 
     printf("Value of c is %d\n", c );
     c = a--; 
     printf("Value of c is %d\n", c );
 }

output

Value of c is 21
Value of c is 22

if we only write a ++ it shows 22, and if we write a it shows 20, whereas when c is assigned as above it is displayed as 21 and 22, why is that?

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4 answers


In the case of ++ ++, this is a postfix operator. So the first value of a is assigned to c and then a is incremented. The value for c is 21.



Now the current value of a is 22. In the case of c = a--, the value of a (ie 22 is assigned) to c and then a is decremented. Therefore, the value of c is 22.

+2


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c = a++;

a++

means returning a value a

and increasing a value a

, so

c = 21;/* Because a = 21 before incrementing */

a--

means the same as value and decrement, so



c = 22;

When we're on the line c = a--

a

is 22

due to the previous operation a++

after this line a

is decremented and a

equals 21.

Yes, since you are assigning a value c

, the value is a

returned to it before ++

or--

+1


source


In C. there are operators postfix

and prefix

. When you use an operator postfix

then the assignment is done and then the operation . If you want to perform assignment and operation on one line, you need to use the statement prefix

where the operation is performed and then the assignment . If you change your code below you will get the expected result

     c = ++a; 
     printf("Value of c is %d\n", c );
     c = --a; 
     printf("Value of c is %d\n", c );

This link will give you more understanding

0


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c=a++;


equivalent c=a;a+=1;


and c=a--;


equivalent c=a; a-=1;

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