Assignment Operators

C assignment operators are used to assigned the value of a variable or expression to a variable. 
The syntax of assignment operators is:
var = expression;
var = var;
Beside = operator, C programming language supports other short hand format which acts the same assignment operator with additional operator such as +=, -=, *=, /=, %=.
var +=expression; //is same as
var = var + expression;
Each assignment operator has a priority and they are evaluated from right to left based on its priority. 
Here is assignment operator and its priority: =, +=, -=, *=, /=, %=.
A simple C program to demonstrate assignment operators:
#include <stdio.h>
/* a program demonstrates C assignment operator */
void main(){
    int x = 10;
    /* demonstrate = operator */
    int y = x;
    printf("y = %d\n",y);
    /* demonstrate += operator */
    y += 10;
    printf("y += 10;y = %d\n",y);
    /* demonstrate -= operator */
    y -=5;
    printf("y -=5;y = %d\n",y);
    /* demonstrate *= operator */
    y *=4;
    printf("y *=4;y = %d\n",y);
    /* demonstrate /= operator */
    y /=2;
    printf("y /=2;y = %d\n",y);
}
Here is the output:
y = 10
y += 10;y = 20
y -=5;y = 15
y *=4;y = 60
y /=2;y = 30