Extracting Substrings

cut

void cut(unsigned long start_idx, unsigned long end_idx);

The cut() function will replace a string with a truncated version. For performance and to prevent losing stack-based memory, the cut() function does not reallocate a new smaller string buffer. If you wish to do this, call compact() after calling cut(). The cut() functions operates with $O(1)$ efficiency if cutting only from the right and $O(n)$ efficiency otherwise.

Str x = "Hello There";
x.cut(0,5);           // x = "Hello"
x = "Hello There";
x.cut(6, x.length()); // x = "There"
x = "Hello There";
x.cut(3, 8);          // x = "lo Th"

copyRange

void copyRange(const Str& str, unsigned long start_idx, 
               unsigned long end_idx);

The copyRange() function copies a substring from another string into this one. Do not give the same object as an argument to copyRange() (i.e. do not call x.copyRange(x,...)). Use cut() instead.

The copyRange() function will reallocate a new buffer to hold the substring if (and only if) the current buffer is not large enough to hold the copy. The copyRange() function operates with $O(n)$ efficiency.

char* buff[8];        // Build y on the stack, just for fun
Str y(buff, 8);

Str x = "Hello There";
y.copyRange(x, 0, 5);           // y = "Hello", buff = "Hello"
y.copyRange(x, 7, x.length()); // y = "here", buff="here"
y.copyRange(x, 1, x.length()); // to big for buff, y = "ello There", buff="here"