README.md

Strings

Example	Topic
CString	char arrays, strlen vs sizeof, copy/concat/compare, strtok, strtod
StdString	std::string operations, searching, conversions, std::string_view
StringFormatting	std::format, concatenation, std::ostringstream, snprintf, custom formatters

1. Three kinds of strings

Type	Owns the characters	Knows its length	Typical use
const char*	no	no (scans for '\0')	C APIs, string literals
std::string	yes	yes	storing and modifying text
std::string_view	no	yes	read-only parameters (C++17)

void print(std::string_view text);  // accepts literals, std::string, substrings - without copies

A std::string_view must not outlive the characters it refers to: std::string_view view = std::string("temporary"); dangles immediately.

2. C string pitfalls

• sizeof(pointer) is the size of the pointer, not the length of the text.
• strcpy, strcat and sprintf do not check buffer sizes: prefer snprintf.
• strncpy does not add '\0' when the source is too long.
• Compare with strcmp, not ==, which compares addresses.
• atoi returns 0 on error. strtol and strtod report where parsing stopped.

3. Formatting (C++20)

std::format("{:>8}|{:<8}|{:^8}", "r", "l", "c");  // alignment
std::format("{:.2f} {:#x} {:08.3f}", 3.14159, 255, 2.5);
std::format("{1} {0}", "world", "hello");        // positional arguments

std::format is type-safe, and a format string that does not match the arguments fails at compile time.