find bugs in the c++ code below

Question

I have been asked to find bug in the following code This code just prints abcdef, it seems pretty harmless to me but will appreciate any suggestions

#include <iostream>
using namespace std;

const char* append(const char* s1, const char* s2) {    
    string s(s1);    
    s += s2; 
    return s.c_str();
} 
void foo() { 
    const char* total = append("abc", "def"); 
    cout<<"total = "<<total<<endl;
}

int main() { 
  foo();
  return 0;
}

possible duplicate of [Returned string value becomes garbage](http://stackoverflow.com/questions/15020105/returned-string-value-becomes-garbage) — Ken Y-N, Nov 04 '14 at 06:06
when s goes out of scope it will delete the pointer and hence will return from append function will consist of junk characters. — Sumeet, Nov 04 '14 at 06:08
@TonyD I think it's implementation defined whether or not headers will include others, i.e. `` and ``. — , Nov 04 '14 at 07:10
@Tushar Relevant: http://stackoverflow.com/questions/6441218/can-a-local-variables-memory-be-accessed-outside-its-scope — πάντα ῥεῖ, Nov 04 '14 at 08:07

score 0 · Accepted Answer · answered Nov 04 '14 at 06:21

0

You have a dangling pointer. s is destroyed when it goes out of scope, meaning the pointer to its internal data is no longer valid.

answered Nov 04 '14 at 06:21

find bugs in the c++ code below

1 Answers1