Increment Decrement Operators

Increment Decrement Operators C++ includes two useful operators. These are increment and decrement operators, ++ and –.

1. Increment Operator (++) – add 1 to its operand.
   • Syntax :    ++variable_name; (or) variable_name++;
   • Versions:
     • Preincrement (++variable_name) : Value of variable is incremented before assigning it to variable. Example : ++m;
     • Postincrement (variable_name++) : Value of variable is incremented after assigning it to variable. Example : –m;
2. Decrement Operators (–) → subtracts 1 from the operand
   • Syntax :   —variable_name; (or) variable_name–;
   • Versions:
     • Predecrement (–variable_name) : Value of variable is incremented before assigning it to variable. Example : ++m;
     • Postdecrement (variable_name–) : Value of variable is incremented after assigning it to variable. Example : –m;

 

Increment Decrement Operators – 

S.no	Operator type	Operator	Description
1	Pre-increment	++p	Value of p is incremented before assigning it to variable p.
2	Post-increment	p++	Value of p is incremented after assigning it to variable p.
3	Pre-decrement	– –p	Value of p is decremented before assigning it to variable p.
4	Post-decrement	p– –	Value of p is decremented after assigning it to variable p.

Difference between preincrement and postincrement operators in C++ with an example.

#include<iostream.h>
int main()
   {
   clrscr();
   int a=6,x;
   x=++a + 2*a;
   cout<<"when a=6, calculate x=\n";
   cout<<"\n1)x=(++a + 2*a)\n x="<<x;
   a=6;
   x=a++ + ++a;
   cout<<"\n2)x=(a++ + ++a)\n x="<<x;
   a=6;
   x=++a + a++;
   cout<<"\n3)x=(++a + a++)\n x="<<x;
   a=6;
   x=++a + ++a;
   cout<<"\n4)x=(++a + ++a) \n x="<<x;
   a=6;
   x=a++ + a++;
   cout<<"\n5)x=(a++ + a++) \n x="<<x;
   return 0;
   }

Output :

when a=6, calculate x=
1)x=(++a + 2*a)
  x=21
2)x=(a++ + ++a)
  x=14
3)x=(++a + a++)
  x=14
4)x=(++a + ++a)
  x=16
5)x=(a++ + a++)
  x=12

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