problem with output of the program on different OS

I have a C program which I created on Windows machine. I have compiled
and executed the program on windows machine and it gives me the
consistent output every time i run it. for eg.

input a = 2, b =3

lets say a sum operation is to be performed, then:

output: 5

The output is always consistent and correct with regards to input.

I tried to run the program on my linux machine. The program compiles
and executes but I'm getting strange results. For eg. for the problem
of addition above:

input a = 2 b = 3

output: 1

i execute the program again:

input a = 2 b = 3

output: 6

and again:

input a = 2 b= 3

output 0

What is happening ?