Why does c++ accept assigning bigger string to a smaller char array?

Question

For instance I would expect some kind of error message while or after executing the following code as shown:

#include <iostream>
using namespace std;

int main(){
    char name[10];

    cout << "Who are you?\n Enter your name: ";
    cin >> name;
    cout << "You are "<< name << "\n";

    return 0;
}

and compiling and executing, for instance with g++ -Wall test.cpp -o test.x and executing test.x

Enter name: abcdefghijklmnopqrstuvyz

so the system reply back:

you are: abcdefghijklmnopqrstuvyz

So created an array of type char with 10 places but it could store much more than 10. So the program went on more memory spaces than what I would expect. I was wondering why the compiler (in this case g++) allows that ?

Why should everyone else who knows how to read strings have to pay just so that you get a warning? Those warnings have would have a runtime cost. — Kerrek SB, Jul 03 '17 at 13:56
Closely related IMO: https://stackoverflow.com/questions/367633/what-are-all-the-common-undefined-behaviours-that-a-c-programmer-should-know-a — Rakete1111, Jul 03 '17 at 13:56
What has the compiler to do with anything? By the time you're entering your name, the compiler is not running anymore. — Kerrek SB, Jul 03 '17 at 13:57
C++ have no run-time bounds-checking for arrays. To make sure your program do not write out of bounds is *your* responsibility. — Some programmer dude, Jul 03 '17 at 13:57
This comes up a lot, because undefined behavior is very confusing. This demonstrates the enabler of all hacks - buffer overrun. — Sergey Kalinichenko, Jul 03 '17 at 13:58
C++ compilers are designed with the bold assumption that programmer is smart enough to not to overwrite buffer or not to create an endless loop. — user7860670, Jul 03 '17 at 14:00
Well I would expect a warning but rather an error message. Is this not some kind of memory issue? Memory leak for instance? — Lindomar Carvalho, Jul 03 '17 at 14:02
Static code analyzers may detect some issues of this sort during compilation, dynamic code analyzers may detect some issues of this sort during runtime. You better use both. — user7860670, Jul 03 '17 at 14:05
People are not all the time smart enough. And second I am not pretending to do this, just to learn what and where I can make mistakes while programming. By the way I am not an expert in the field and that it is why I did the question !! — Lindomar Carvalho, Jul 03 '17 at 14:06

Why does c++ accept assigning bigger string to a smaller char array?

0 Answers0