GATE | GATE-CS-2005 | Question 32

Consider the following C-program:

double foo (double); /* Line 1 */

int main()
{

    double da, db;

    // input da

    db = foo(da);

}

double foo(double a)
{
    return a;
}

The above code compiled without any error or warning. If Line 1 is deleted, the above code will show:
(A) no compile warning or error
(B) some compiler-warnings not leading to unintended results
(C) some compiler-warnings due to type-mismatch eventually leading to unintended results
(D) compiler errors

Answer: (D)
Explanation: Refer What happens when a function is called before its declaration in C?
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