Question

I have two strings, e.g.:

• str1 = "aaabbbcccdddeee"
• str2 = "aaabbbccc"

How to do something like str1 - str2 to get the dddeee substring?

Answer 1

If str2 is guaranteed to be a prefix of str1, then this will suffice:

const char *str3 = &str1[strlen(str2)];

which is equivalent to this: (as @James points out in the comments)

const char *str3 = str1 + strlen(str2);

Of course, str3 is just a pointer into one of the original strings. If the contents of the original string changes, then so will your result. So you may want to create a copy, using malloc() and strcpy() (and then free() at some point).