When a variable is not initialized in main function it contains garbage value. This can be well seen from the example below

main()
{
int x;
printf(“%d”,x);
z= sample()
}

sample()
{
printf(“Testing program”);
}

Output is

    x=80

Testing program

The above program prints a garbage value and the output testing program. This is because the variable x is not initialized and so the variable x had garbage value which is printed first then the function sample is called which gave output as testing program. Thus it is essential to initialize variables in main () function.