C++ Assignment Operators

• Assignment Operator (=)

Assignment operators are used to assign values to variables. In the example below, we use the assignment operator (=) to assign the value 10 to a variable called x:

Example

int x=10;

Try it yourself! 

Operator	Expression	Equivalent to...	Try it
=	x=5;	x=5;	Try it

For example, let's have a look at the following code - I have included the evolution of the content stored in the variables as comments:

// assignment operator
#include <iostream>
using namespace std;
int main ()
{
  int a, b;         // a:?,  b:?
  a = 10;           // a:10, b:?
  b = 4;            // a:10, b:4
  a = b;            // a:4,  b:4
  b = 7;            // a:4,  b:7

  cout << "a:"<<a<<"\n";
  cout << "b:"<<b;
}

Try it

• Compound Assignment Operator (+=, -=, *=, /=, %=, &=, |=, ^=, >>=, <<=)

Compound assignment operators modify the current value of a variable by performing an operation on it. They are equivalent to assigning the result of an operation to the first operand:

A list of all compound assignment operators

Operator	Expression	Equivalent to...	Try it
+=	x+=3;	x=x+3;	Try it
-=	x-=3;	x=x-3;	Try it
*=	x*=3;	x=x*3;	Try it
/=	x/=3;	x=x/3;	Try it
%=	x%=3;	x=x%3;	Try it
&=	x&=3;	x=x&3;	Try it
|=	x|=3;	x=x|3;	Try it
^=	x^=3;	x=x^3;	Try it
>>=	x>>=3;	x=x>>3;	Try it
<<=	x<<=3;	x=x<<3;	Try it

and the same for all other compound assignment operators. For example:

// compound assignment operators
#include <iostream>
using namespace std;

int main ()
{
  int a, b=3;
  a = b;
  a+=2;             // equivalent to a=a+2
  cout << a;
}