Function calling and return statement

Asked Oct 07 '20 at 10:29

Active Oct 07 '20 at 10:42

Viewed 59 times

In the given C++ code when the statement n isn't present the function abc returns 10 .I.e def(10) acts as if it is a return statement but it isn't. The output of the function is always 10 and doesn't lead to undefined behaviour when statement n as given in code isn't present in the code. I am using sublime text 3. So why it is behaving in such a manner or am I missing any concept

#include<bits/stdc++.h>
using namespace std;
int def(int x){
    return x;
}
int abc(int x){
    def(10);
    return x;//statement: n
}
int main(){
    cout<<abc(5);
}

edited Oct 07 '20 at 10:42

asked Oct 07 '20 at 10:29

Praveen Kumar

1

not returning something in a function that is declared to return something is undefined behavior. The boring truth is: If you remove that statement your code is invalid and compiling it can result in anything – 463035818_is_not_an_ai Oct 07 '20 at 10:31
1

TL;DR: Undefined behavior is undefined. – Simon Kraemer Oct 07 '20 at 10:31
to get 10 as output, you need to call return def(10), instead of return x in func abc – vishal Oct 07 '20 at 10:35
but the code always give answer as 10 and doesn't give an error please try it with your system – Praveen Kumar Oct 07 '20 at 10:38
the code as posted prints 5 not 10 (https://godbolt.org/z/se6EMb) without that line it can print anything. 42 would be a completely valid output and you won't get errors. Turn on warnings and read here: https://en.cppreference.com/w/cpp/language/ub – 463035818_is_not_an_ai Oct 07 '20 at 10:40
yeah it prints 5 with statement n but without it ,it gives 10 as output – Praveen Kumar Oct 07 '20 at 10:43
it prints 10 because the code is invalid in that case. Compilers are not made to compile invalid code. If you still ask them to do so the result can be anything – 463035818_is_not_an_ai Oct 07 '20 at 10:45

Function calling and return statement

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