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Increment and Decrement Operators

2 min read

Tag: Programming MOC, C MOC

Increment ++ and Decrement — Operator as Prefix and Postfix

In programming (Java, C, C++, JavaScript etc.), the increment operator ++ increases the value of a variable by 1. Similarly, the decrement operator -- decreases the value of a variable by 1.

a = 5
 
++a;          // a becomes 6
a++;          // a becomes 7
--a;          // a becomes 6
a--;          // a becomes 5

Simple enough till now. However, there is an important difference when these two operators are used as a prefix and a postfix.

++ and — operator as prefix and postfix

  • If you use the ++ operator as a prefix like: ++var, the value of var is incremented by 1; then it returns the value.
  • If you use the ++ operator as a postfix like: var++, the original value of var is returned first; then var is incremented by 1.

The -- operator works in a similar way to the ++ operator except -- decreases the value by 1.

Let’s see the use of ++ as prefixes and postfixes in C, C++, Java and JavaScript.

Example: C MOC Programming

#include <stdio.h>
int main() {
   int var1 = 5, var2 = 5;
 
   // 5 is displayed
   // Then, var1 is increased to 6.
   printf("%d\n", var1++);
 
   // var2 is increased to 6 
   // Then, it is displayed.
   printf("%d\n", ++var2);
 
   return 0;
}

Example: C++

#include <iostream>
 
using namespace std;
 
int main() {
   int var1 = 5, var2 = 5;
 
   // 5 is displayed
   // Then, var1 is increased to 6.
   cout << var1++ << endl;
 
   // var2 is increased to 6
   // Then, it is displayed.
   cout << ++var2 << endl;
 
   return 0;
}

Example: Java Programming

class Operator {
    public static void main(String[] args) {
        int var1 = 5, var2 = 5;
 
        // 5 is displayed
        // Then, var1 is increased to 6.
        System.out.println(var1++);
 
        // var2 is increased to 6
        // Then, var2 is displayed
        System.out.println(++var2);
    }
}

Example 4: JavaScript

let var1 = 5, var2 = 5;
 
// 5 is displayed
// Then, var1 is increased to 6
console.log(var1++)
 
// var2 is increased to 6
// Then, var2 is displayed
console.log(++var2)

The output of all these programs will be the same. Output 5 6

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