Question

see once in hurry i have written

#include <stdio.h>

static flag;            
int main()
{
printf("flag is %d",flag);
return 0;
} 

it does not not give any warning or error and works fine. I dont understand why this is going work?

Answer 1

C assumes int when type is missing. It is also true for function definitions and their parameters:

// same as int add(int x, int y)
add(x,y) { return x + y; }

// same as int main()
main()
{
}