A set of expression separated by comma is a valid
constant in the C language. For example i and j are declared by the statements
int i , j;
In the above declaration, right hand side consists of two
expressions separated by comma. The first expression is j=10 and second is j+20.
These expressions are evaluated from left to right. ie first the value 10 is
assigned to j and then expression j+20 is evaluated so the final value of i will