Not getting right Output of Character Array

Question

Possible Duplicate:
Pointer to local variable

#include <iostream>
using namespace std;

char* func();

int main() {
    char* str;
    str = func();
    cout<<str;
    return 0;
}

char*  func() {
    char * str;
    char p[] = "priyanka is a good girl";
    str = p;
    cout<<str<<"\n";
    return str;
}

gives the output,

priyanka is a good girl

priy

I did not understand what just happened here, why an incomplete array was given as output. I am a little new with this. Please help.

`rpiyanka is a good girl` no she is not. She does not indent her code! — Aniket Inge, Nov 08 '12 at 19:02

score 4 · Answer 1 · edited Nov 08 '12 at 19:01

4

Your function func() returns a pointer to a local variable, which later causes undefined behaviour when you try to access it.

edited Nov 08 '12 at 19:01

FailedDev

26,680
9
53
73

answered Nov 08 '12 at 18:58

Carl Norum

219,201
40
422
469

oh yes, sending a pointer to local variable doesn't make any sense :P. thanks – priyanka Nov 08 '12 at 19:05
I'd add that it's allocated on the stack. When the function returns, its stack frame (where the pointer points to) is deallocated, which is why you can get a partially correct/jumbled output, when some but not all of the old stack frame has been reused by something else. – GraphicsMuncher Nov 08 '12 at 19:13

score 1 · Accepted Answer · answered Nov 08 '12 at 19:05

1

In func2() char p[] is a local variable initialized on stack. Returning a pointer to stack variable is a bad idea(and is undefined behaviour as well), and I think your string "priyanka is a good girl" got overwritten when the function returned.

answered Nov 08 '12 at 19:05

Aniket Inge

25,375
5
50
78

Not getting right Output of Character Array

2 Answers2