Compile Time Format String

Type-safe format string I/O functions similar to cstdio interfaces using C++20.

Live Demo

Usage

#include "include/ctfs.hpp"

int main()
{
  // Prints "Hello 3 world".
  ctfs::print<"Hello %d %s\n">(3, "world");
  // Prints "value1: 005, value2: 2.30".
  ctfs::print<"value1: %03d, value2: %.2f\n">(5, 2.3f);

  int temp = 5;
  // Prints "64bit-unsigned: 18446744073709551615, pointer: 0x...".
  ctfs::print<"64bit-unsigned: %llu, pointer: %p\n">(UINT64_MAX, &temp);

  // error: invalid conversion from ‘const char*’ to ‘int’
  ctfs::print<"This will fail to compile: %d %d\n">(3, "");


  char s[256]{};
  // Write "sprint 4294967295 3.140000" to the buffer `s`.
  ctfs::sprint<"sprint %u %f">(s, -1, 3.14);
  puts(s);

  // error: too few arguments to function
  // ctfs::sprint<"fail to compile: %s %s">(s, "Hello");

  FILE *f = fopen("./main.txt", "w");
  // cat main.txt: "fprint 2.718 b"
  ctfs::fprint<"fprint %g %c">(f, 2.718, 'a' + 1);

  // error: too many arguments to function
  // ctfs::fprint<"fprint %d %d %d">(f, 1, 2, 3, 4);

  fclose(f);

  int a, b;
  ctfs::scan<"%d %d">(&a, &b);
  ctfs::print<"%#x (%d) %#x (%d)\n">(a, a, b, b);
}

g++-11 -std=c++20 required to build.

NOTE

It supports stdout functions (printf, sprintf, and fprintf) and stdin functions (scanf, sscanf, fscanf). However, widechar versions (wprintf, ...) and detailed format specifiers for stdin functions are currently not supported.

License

MIT