C is a versatile language: it can be used to perform many functions. The standard C library comes with a bunch of functions in stdio.h a header file that helps output information to the terminal, string buffer, or file stream.

C Standard I/O Printing Functions

Formatted Output Functions

printf: Prints formatted output to the standard output stream (stdout).
fprintf: Prints formatted output to a specified output stream (FILE *stream).
sprintf: Writes formatted output to a string buffer (char *str).
snprintf: Writes formatted output to a string buffer, up to a specified maximum size (char *str).
dprintf: Prints formatted output to a specified file descriptor (int fd) (POSIX standard).

Variable Argument List (va_list) Functions

vprintf: Prints formatted output to stdout using a variable argument list (va_list).
vfprintf: Prints formatted output to a file stream using a variable argument list.
vsprintf: Writes formatted output to a string buffer using a variable argument list.
vsnprintf: Writes formatted output to a string buffer, up to a specified size, using a variable argument list.
vdprintf: Prints formatted output to a file descriptor using a variable argument list (POSIX standard).

String and Character Output Functions

puts: Writes a string followed by a newline to stdout.
fputs: Writes a string to a specified file stream (FILE *stream).
putchar: Writes a single character to stdout.
fputc: Writes a single character to a specified file stream (FILE *stream).
putc: Writes a single character to a specified file stream (often implemented as a macro).

Binary and Obsolete Functions

putw: Writes an integer to a specified file stream (obsolete, non-standard).
fwrite: Writes blocks of binary data to a file stream.

But here, the interest is on printf function. Knowing how to create a function like this requires knowledge of the different subjects that constitute the C programming language, such as parsing a variable number of arguments. A number of tutorials, documents, or blogs give information on how the function is designed and the steps the implementation should follow. The most famous document in this realm is the Secrets of "printf." The document will serve as a guide for this series. In my case, I'll name my custom function printfn, with the "n" ending to denote a newline; it will add a newline after every print statement, extending the functionality offered by printf. This blog is the start of a series that will guide the creation of the function through to the end; I'll be documenting the steps I took to reach the end goal. Thus, it is subject to change over time until the end of the project. I welcome any suggestions or changes. The project is hosted on GitHub.