What is difference between postfix a++ and prefix ++a?

Hi, I'm Golam Rabbani. Today I will discuss about postfix and prefix operator.

Greetings! How are you all? Hope everyone is well.

#Topic 1: a++ is called post increment and will return a then increment a by 1

Equivalent to a++? Answer: a = a+1.

If a = 5;

print a++; //result = 5

print a; //result = 6

Program:

#include<stdio.h>
int main(){
    int a=5;
    printf("%d\n",a++);
    printf("%d\n",a);
    return 0;
}

#Topic 2: ++a is called pre increment and will increment a by 1

Equivalent to ++a? Answer: a = a+1. But this is different. What’s different?

If a = 5;

print ++a; //result = 6

Program:

#include<stdio.h>
int main(){
    int a=5;
    printf("%d\n",++a);
    printf("%d\n",a++);
    return 0;
}

Test your knowledge.

Question 1: pre increment and post increment in c program?

#include<stdio.h>
int main(){
    int a=5;
    printf("%d,%d,%d,%d,%d,%d,%d\n",a++,++a,a++,++a,a++,a++,++a);
    printf("%d",a);
}

Output:

a=5.

Remember ++a always view total result. This program continue 7 time increment. So, ++a always view a=5+7; a=12.

This case.

N = Not calculate. I mean a=12.

F = Count start > Right to left. When get first a++.

S.L	7	6	5	4	3	2	1
Count	6	5	4	3	2	1
Calculation	F a=5+6	N	F a=5+4	N	F a=5+2	F a=5+1	N
Operator	a++	++a	a++	++a	a++	a++	++a
Result	11	12	9	12	7	6	12

Compiler Result:

 Thank you everyone.