String Length

You can determine the number of characters in a string using the length() or size() methods (they are equivalent in C++). Both run in O(1) time and return std::string::size_type (an unsigned type).

You can check if a string has no characters using the empty() method, which returns true (1) if the string is empty.

A string stores both its length (the number of code units it currently holds) and its capacity (the amount of memory allocated). Capacity may be larger than length to reduce reallocations when the string grows.

In a narrow std::string, size()/length() count bytes, not human-visible characters. With UTF-8 text, multi-byte code points (e.g., emoji) make size larger than the perceived character count.

If you need code-point counts in UTF-8, you can approximate by counting non-continuation bytes; for true user-perceived characters (grapheme clusters), a text library is required.