c++ - Program crashes when trying to set a character of a char array

Question

I got this weird behavior of my programm, that i cant figure out. My professor showed me a flaw in my programm, where i just copy a char pointer when i construct an object instead of making a new copy of the whole array, so you can fool around with it. He demonstrated this with similar code like this.

For the code:

char sweat[] ="Sweater";
warenkorb = new WareImKorb(new Textil (205366,4.2,sweat,40),2,warenkorb);
sweat[0] = '';

now if i instead make it:

char* sweat ="Sweater";

the program runs fine till i try sweat[0] = ''; It simply crahes then.

However this works: char cc[] ="Sweater"; char* sweat = cc;

It is really bugging me, that i dont understand, why version 1 does not work. Hope you guys can help me out, or else i will go crazy wondering about this.

Answer 1

"Sweater" is a string literal, which may reside in read-only memory. Using the char[] syntax copies this literal into a char array, using the char * syntax (which really should be const char *) just points at the original string literal.