Question

#include <iostream>
#include <cstring>
using namespace std;
int main() {
  char sor[6] = "hello";
  char des[6] = "hello";
  strcat(des,sor);
  cout << des;
}

When i start the debugging of the program it gives the following error along with the console output (behind it) :

why is it so ? If there is anything wrong with the code ,please give a suggestion

Answer 1

While increasing the size of the string char-array would help you in this situation, let me propose to actually use C++ features; don’t code C when you want to code C++:

#include <iostream>
#include <string>
using namespace std;
int main() {
  string sor = "hello";
  string des = "hello";
  des += sor;
  cout << des;
}

Why not char arrays

Suhail asked why char-arrays are bad:

One shouldn’t be using char-arrays because of situations like exactly this. Many more dangerous situations exist; effectively, when you are using C arrays, there’s a certain danger that your program is subject to buffer-overflow attacks.

You were actually very lucky that you directly received the exception; but more often than you like those bugs are subtle and don’t uncover themselves for days, months, years; and then, possibly, your customer will be in in the daily news for being cracked and losing their customers credit card information into the public.

Using C++ facilities like string or stringstream, this can be avoided easily.

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• Buffer Overflow (for examples, check the history section)
• Format String Attacks (not directly related to specifically this question, but another example of char-array vulnerabilities and using C instead of C++)