Junk after C++ string when returned

Question

I\'ve just finished C++ The Complete Reference and I\'m creating a few test classes to learn the language better. The first class I\'ve made mimics the Java StringBuilder class

Answer 1

Does index contain the length of the string you're copying from including the terminating null character? If it doesn't then that's your problem right there.

If stringArrary isn't null-terminated - which can be fine under some circumstances - you need to ensure that you append the null terminator to the string you return, otherwise you don't have a valid C string and as you already noticed, you get a "bunch of junk characters" after it. That's actually a buffer overflow, so it's not quite as harmless as it seems.

You'll have to amend your code as follows:

char *copy = new char[index + 1];

And after the copy loop, you need to add the following line of code to add the null terminator:

 copy[index] = '\0';

In general I would recommend to copy the string out of stringArray using strncpy() instead of hand rolling the loop - in most cases strncpy is optimized by the library vendor for maximum performance. You'll still have to ensure that the resulting string is null terminated, though.