Assigning Data type to a User Defined Function

Question

I'm new to programming and I was pondering about it.

In C language when a Function is declared by the user. What happens if the data type of the function is not assigned. My question is basically that what is the difference between a function like these:

int main()
{
    statements.....
}

main()
{
    statements.....
}

what happens if we assign the data type? what happens if we don't? Any help. Please Thank You.

The first version is a function that returns an `int`. The second one is incorrect C. — Jabberwocky, May 15 '18 at 15:48
It would be a syntax error according to C11. But K&R C allowed this and the return type defaulted to `int`. Most compilers today still allow this for backward compatibility. — Ajay Brahmakshatriya, May 15 '18 at 15:48
Possible duplicate of [Function without return type specified in C](https://stackoverflow.com/questions/30542092/function-without-return-type-specified-in-c) — underscore_d, May 15 '18 at 15:52

score 3 · Accepted Answer · answered May 15 '18 at 15:49

3

It's referred to as the implicit int rule. Essentially, it assumes it's an int. Though this is not in the C standard (as of C99).

See here for a more detailed answer.

answered May 15 '18 at 15:49

platinum95

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Assigning Data type to a User Defined Function

1 Answers1