What does a c++ in function return without a return statement return? [duplicate]

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Why does flowing off the end of a non-void function without returning a value not produce a compiler error? (9 answers)

What happens when a function that returns an object ends without a return statement (3 answers)

Closed 2 years ago.

In a test, one of my classmates wrote the following function, to flip a number:

int tukor(int n)
{
    int k=0;
    while(n!=0)
    {
        k=k*10+n%10;
        n=n/10;
    }
    n=k;
}

You will notice a complete lack of any return statements, but when cout<<tukor(1234); is run (namespaaace std is used), it outputs 4321. Now the entire class is confused as to how this is possible, even after the teacher added the lines n=0;n=12; at the end of the function. It has worked for all test cases so far.

Is this caused by undefined behavior or something similar?

EDIT: changing k before the n=k statement changes the return value, and if it is removed, the return value is 0.

来源：https://stackoverflow.com/questions/50346184/what-does-a-c-in-function-return-without-a-return-statement-return