P0457R0 String Prefix and Suffix Checking

Checking, whether or not a given string starts with a given prefix (or ends with a given suffix) is a common task.

This proposal adds two member functions

starts_with
ends_with

to class templates

std::basic_string
std::basic_string_view

Implemented in standard libraries of many other programming languages as a member of string/string-like classes. For example:

Python
Java, Scala
.NET langauges
Rust
Swift

Implemented in some C++ libraries:

Qt (QString, QStringRef)
boost
- original string_ref (string_view)
- boost::algorithm::starts_with free function

Used in various codebases

Name	`starts_with`	`ends_with`
Qt	1193	953
Webkit	304	142
LLVM	113	38

Discussion in Bristol

Alan was concerned about "findXXX" and starts_with/end_with functions, and suggested that they be free functions.

Sam said that he was in favor of having starts_with/end_with as member functions.

Dietmar suggested that starts_with/end_with should be in a separate proposal, and are independent of string_view. He also said that we are not designing a new interface here, we need to be more or less compatible with std::string.

Design decisions

Member function vs. free function
Overload set
- string_view
- charT