What does this weird function definition mean?

Question

I came across this C program in a blog post:

main()
{
    int n;
    n = 151;
    f(n);
}

f(x)
int x;
{
    printf("%d.\n", x);
}

The post doesn't explain it. Can anybody explain what this weird function definition means?

Answer 1

This is the K&R style of C code, it's still valid C syntax, but I suggest you not using it in new-written code.

f(x)
int x;

is equivalent to ANSI C:

void f(int x)

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K&R C is the C language described in the first edition of the book C programming language by Brian Kernighan and Dennis Ritchie, and named after the two authors. The second edition of the book updated to use ANSI C.