printf

A School 21 project.

• Testers
  • paulo-santana/ft_printf_tester
  • Tripouille/printfTester
• Misc
  • <stdarg.h>
  • stdarg.h - Wikipedia
• C debugging, compilation and building
• Пилим printf() своими руками. Часть первая. | by Weston Normcore | Medium

  • Важное отступление: чтобы считать аргумент типа char, нужно передать в va_arg тип int. Особенностей реализации мы здесь касаться не будем, просто запомните, что char считывается через int. More info.

Return value of built-in printf is the number of characters printed (returned). If an error occurred, the value is negative.

• Ensure that functions from libft don’t leak into printf. UPD: that’s kinda impossible under Norminette and subject constraints.

Variadic functions in C are dangerous. In case of type mismatch or wrong number of arguments the program crashes. See this and this questions on Stack Overflow.

In case of too many (or to few) arguments, passed to the built-in printf, a warning is raised. Though with flags -Wall -Werror -Wextra it won’t even compile. In case of argument type mismatch, I think the behavior is undefined.

The format string is composed of zero or more directives: ordinary characters (not %), which are copied unchanged to the output stream; and conversion specifications, each of which results in fetching zero or more subsequent arguments. Each conversion specification is introduced by the character %, and ends with a conversion specifier. In between there may be (in this order) zero or more flags, an optional minimum field width, an optional precision and an optional length modifier.