Function inside function in C

Question

Anybody please elaborate these error:-

void main()
{
    int a=5, b=60, func();

    printf("\nI am in main-1");

    int func(){
        printf("\nI am in funct");
        return 1;
    }
    func();
    printf("\nI am in main-2");
}

The errors I get are:

• In function 'main':
• Line 8: error: static declaration of 'func' follows non-static declaration
• Line 4: error: previous declaration of 'func' was here
• Line 3: warning: return type of 'main' is not 'int'

I think C allows nested class because the following code is working fine:

void outerfunc()
{
    int func()
    {
        printf("\nI am in funct");
        return 1;
    }

    func();
}

void main()
{
    printf("\nI am in main-1");

    outerfunc();
    printf("\nI am in main-2");
}

Answer 1

You are using an extension of the GNU C Compiler which allows the declarations of nested functions. The error comes from the fact, that forward declarations of nested functions under GCC's extension need to be prepended with the auto keyword.

int a=20,b=11;
int main()
{
  int a=5, b=60; 
  auto int func(); // <--------- here
  func(); // <- call it
  printf("\nI am in main-1");

  int func(){
  printf("\nI am in funct");
  return 1;
  }

printf("\nI am in main-2");
 return 0;
}

See http://gcc.gnu.org/onlinedocs/gcc/Nested-Functions.html for more details.

Answer 2

ANSI C doesn't allow nested function definition. And your main function should return int.