What is comma operator ?

It is a special type of operator which is used to link the related expression together.  The common use of comma operator is in variable declarations where we declare more than one variable at a time and a line.

It first evaluates the left expressions and then right expressions.  The example of comma operator is as follows:

int a, b, c;

for ( i=0, j=1; i<=10, j>=10; j++, i++)