Lesson 212 +5 XP

<string> Member Functions Reference

The std::string class manages text for you: growth, storage, destruction, the whole package. Here are the member functions you'll need.

Function	Example	What it does
`length()`	`s.length()`	number of characters total
`size()`	`s.size()`	same as `length()`, same letters
`capacity()`	`s.capacity()`	characters the string can hold in its current memory
`empty()`	`s.empty()`	`true` if the string has zero characters
`clear()`	`s.clear()`	remove all characters, size becomes 0
`reserve(n)`	`s.reserve(30)`	pre-allocate memory for at least `n` chars
`resize(n)`	`s.resize(10)`	force the size to `n`, fill new chars with '\0'

Function	Example	Notes
`at(n)`	`s.at(0)`	bounds-checked; throws `out_of_range` on bad index
`operator[]`	`s[0]`	no bounds check - faster, but your job to stay in range
`front()`	`s.front()`	first character
`back()`	`s.back()`	last character

Function	Example	What it does
`append`	`s.append("word")`	add text to the end (same as `+=`)
`insert`	`s.insert(2, "XX")`	insert text at position 2
`replace`	`s.replace(3, 2, "YZ")`	replace 2 chars starting at index 3 with "YZ"
`erase`	`s.erase(2, 3)`	remove 3 chars starting at index 2
`push_back`	`s.push_back('X')`	add one character at the end
`pop_back`	`s.pop_back()`	remove the last character (C++11)

Function	Example	What it returns
`find`	`s.find("needle")`	index of the first niche or `npos` if not found
`substr`	`s.substr(3, 2)`	a shorter string cut from the string

npos is a special "not found" size_t value. Always compare: if (s.find("x") != string::npos).

substr(3) without a length grabs the rest.

Function	Example	What it does
`compare`	`s.compare(t)`	<0 if smaller, 0 if equal, >0 if bigger (dictionary order)
`c_str()`	`s.c_str()`	C-style char pointer version (NUL-terminated, const)
`data()`	`s.data()`	pointer to the character data (no NUL guarantee before C++11)

These live in the std namespace too; you'll already have them after including <string>.

find returns string::npos (a huge number) when nothing is found - compare, don't assume.
at checks bounds and throws; [] is faster and trusts you.
substr creates a new string; it does not copy the original.
Strings auto-grow when you append during use - no manual resize needed.