Formatting library (C++20)
The text formatting library offers a safe and extensible alternative to the printf family of functions. It is intended to complement the existing C++ I/O streams library and reuse some of its infrastructure such as overloaded insertion operators for user-defined types.
#include <format>
#include <cassert>
int main() {
std::string message = std::format("The answer is {}.", 42);
assert( message == "The answer is 42." );
}
Formatting functions
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(C++20)
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stores formatted representation of the arguments in a new string (function template) |
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(C++20)
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writes out formatted representation of its arguments through an output iterator (function template) |
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(C++20)
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writes out formatted representation of its arguments through an output iterator, not exceeding specified size (function template) |
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(C++20)
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determines the number of characters necessary to store the formatted representation of its arguments (function template) |
Extensibility support and implementation detail
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(C++20)
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non-template variant of std::format using type-erased argument representation (function) |
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(C++20)
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non-template variant of std::format_to using type-erased argument representation (function template) |
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(C++20)
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class template that provides access to a formatting argument for user-defined formatters (class template) |
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(C++20)
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class template that defines formatting rules for a given type (class template) |
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(C++20)(C++20)(C++20)
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formatting string parser state (class template) |
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(C++20)(C++20)(C++20)
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formatting state, including all formatting arguments and the output iterator (class template) |
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(C++20)
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argument visitation interface for user-defined formatters (function template) |
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(C++20)(C++20)
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creates a type-erased object referencing all formatting arguments, convertible to format_args (function template) |
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(C++20)(C++20)(C++20)
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class that provides access to all formatting arguments (class template) |
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(C++20)
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exception type thrown on formatting errors (class) |
Notes
Feature testing macro: __cpp_lib_format.
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