Format text with C++20's format library

C++20 introduces the new format() function, which returns a formatted representation of its arguments in a string. format() uses a Python-style formatting string, with concise syntax, type safety, and excellent performance.

The format() function takes a format string and a template, parameter pack, for its arguments:

template< class... Args >
string format(const string_view fmt, Args&&... args );

The format string uses curly braces {} as a placeholder for the formatted arguments:

const int a{47};
format("a is {}\n", a);

Output:

a is 47

It also uses the braces for format specifiers, for example:

format("Hex: {:x} Octal: {:o} Decimal {:d} \n", a, a, a);

Output:

Hex: 2f Octal: 57 Decimal 47

This recipe will show you how to use the format() function for some common string formatting solutions.

Note

This chapter was developed using a preview release of the Microsoft Visual...