Q:

How to write an if statement that's always true without using any variables and operators?

How to write an if condition without using variables and operators? The condition should always be true.
if(condition)
{
    executable statements;
}

A:

Just use any non-zero number to fill the condition in if statement

Examples:
if(1), if(2),  .....so on
similarly
if(-1), if(-2), .....so on

These would be held true for all cases except if(0)
Reason: You can fill the condition with any value except 0. The reason for this is  that generally in C, 

0 is returned by a false condition

and so if you enter a 0, C skips the if block terating the condition to be false.
so your code would be:
if(1)  //I just considered 1
{
    executable statements;
}

