Program crashes when using my strupr implementation

Question

I have written my implementation of strupr function from string library. When I call this function, the program crashes. I have already found an another way to make it working but I am wondering why this verion isn't working. Program crashes exactly during executing the *str = (*str) - 32; instruction.

#include <iostream>

using namespace std;

char * my_strupr(char * str)
{
    char * result = str;

    while(*str != '\0')
    {
        if(*str >= 'a' && *str <= 'z') *str = (*str) - 32;
        str ++;
    }

    return result;
}

int main()
{
    char * str = "some text";
    cout << my_strupr(str);
    return 0;
}

I have to use pointers in this case, they are required in my task.

Post the calling code - you are probably attempting to modify a string literal. — , Oct 13 '17 at 13:35
A classic one: `char * str = "some text";` -> `char str[] = "some text";` — Jabberwocky, Oct 13 '17 at 13:44
@MichaelWalz You're right. It helped and the function don't crash the program anymore. Thanks a lot! :) — Kamil Turek, Oct 13 '17 at 13:50

score 1 · Answer 1 · answered Oct 13 '17 at 13:43

1

The compiler is storing the string in read-only memory, and you are getting a seg-fault trying to modify this memory. This is discussed here

answered Oct 13 '17 at 13:43

PiedPiper

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Program crashes when using my strupr implementation

1 Answers1