Why is the output 5 when sum doesn't return anything?

Asked Dec 05 '17 at 08:24

Active Dec 05 '17 at 08:25

Viewed 67 times

the sum function doesn't have any return type specified also it doesn't have any return statement still the output on a turbo c compiler is 5. Can anyone explain why, I guess it's because the printf function prints 5 characters and maybe returns the number of characters printed.

#include<stdio.h>
#include<conio.h>

sum()
{
    printf("hello");
}

void main()
{

    int k;
    k = sum();

    clrscr();
    printf("%d",k);
    getch();

}

edited Dec 05 '17 at 08:25

Marievi

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asked Dec 05 '17 at 08:24

soda

1

Undefined behavior is undefined. – StoryTeller - Unslander Monica Dec 05 '17 at 08:25
1

Turbo C++ is a history. Do not repeat it. – haccks Dec 05 '17 at 08:26
though it's undefined it's asked in quizzes and tests. – soda Dec 05 '17 at 08:27
Goes to show the worth of those "quizzes and tests". – StoryTeller - Unslander Monica Dec 05 '17 at 08:32
The more interesting question would be "why not?" – Gerhardh Dec 05 '17 at 09:13
Or even better: "Why doesn't your compiler jump into your face and bite if you don't return anything in `sum`. Or when you use `void main()`" – Gerhardh Dec 05 '17 at 09:14
@Michi - `sum` is not a function with a `void` return type. The duplicate fits perfectly – StoryTeller - Unslander Monica Dec 05 '17 at 09:29
1

@Michi - The OP doesn't have a `void` returning function (slight of an oxymoron of a term). Their code should not compile in strict ISO C. But it does, probably because the compiler still implementes the "implicit int" rule. `sum` is an `int` returning function without a return statement. For the purposes of reasoning about this UB, `int` or `char` is immaterial. – StoryTeller - Unslander Monica Dec 05 '17 at 10:04

Why is the output 5 when sum doesn't return anything?

0 Answers0