PRINTF REPOSITORY

Description.

This repository contains a verson of the printf function for C programming language called _printf. This function can do the basic functionality of the original printf function, such as printing chars, strings and integers using the format specifier (%) and the corresponding letter (%c for chars, %d or %i for integers and %s for strings). For more information about the original printf, visit printf manual page.

For this program to run, we suggest you use it in Ubuntu 20.04.2 LTS (Focal Fossa) version, and for compiling, use gcc 9.3.0 version, with the following command:

gcc -Wall -Wextra -Werror -pedantic -std=gnu89 -Wno-format *.c

This command will create the executable a.out. To give it a custom name, add the flag -o followed by the name (e.g gcc -Wall -Wextra -Werror -pedantic -std=gnu89 -Wno-format *.c -o _printf_test). Notice that you need your version of a main.c file to test the function, or you can use the *main.c* file that is in the test directory.

Flowchart

The following is a flowchart design to understand the algorithm of the _printf function:

This repository contains the following files:

holberton.h

This is a header file that contains all the prototypes, libraries and a structure necessary for the program to compile and work.

The structure contained in the program is called "cases" and it has 2 members:

1. char *letter: a pointer to a letter. This letters are the options available to use as a format specifier.
2. int (*f)(va_list): a pointer to a function that receives a va_list pointer and returns an integer. This pointer is the reference to the specified fucntion, depending of the letter specified. Then the structure cases is defined as a type "option".

printf_function.c

This file contains the _printf function (prototype: int _printf(const char *format, ...), which is a variadic function that recieve a mandatory argument (format) and optional arguments that specifies the content that have to appear in the position of the format specifiers. Format is the string that is recieved by _printf, which may contain text algonside format specifiers (e.g _printf("Hello, %s", "World");). In this example, "Hello, %s" is the format string, %s is a format specifier and "World" is the optional argument that will appear in the position where %s is located. This function contains a while loop that evaluates every char in the *format* string, and depending on the case, it prints the char or goes to another function for further evaluation. This function contains an specific case, that is when there is a '%' followed by a null character ('\0'), in which case it doesn't print the '%' and returns -1, no matter how many chars it printed before. The _printf function is accompanied by 2 auxiliary functions:

1. aux_function (prototype: int (aux_function(const char format))(valist)): This function contains a structure type "option" (see holberton.h for further understanding) called _rows that contains each letter of the format specifier that _printf can detect as a call to a particular function (e.g "c" to call print_char function). The while loop below the structure has the purpose of compare the letter that goes after the '%' char in order to know which functions is being called (if there is no coincidende, the function returns NULL and no function is called, so the _printf fucntion will print the % alognside the specified letter without changing it).
2. case_percentage (prototype: int case_percentage(const char *format, va_list list)): This function is called when in the _printf, the format argument contains a %, so this function evaluates which case it is, of the following 4:

• %%, in this case, only one % is printed.
• %, and a correct letter (c, d, i, etc), in this case, the corresponding function contained in the rows structure is called.
• %, and an incorrect letter (y, m, n, etc) in this case the % and the letter are printed.
• %, followed by a new line ('\n') in this case the % and the new line are printed.

_putchar.c

This file contains the function _putchar, which uses the function write to print one byte, and returns the value 1 of 1 byte printed.

print_char_functions.c

This file contains functions that prints text in different formats. This functions returns the count of chars printed This funtcions are:

• print_char (prototype: int print_char(va_list c)): This function prints a single char.
• print_str (prototype: int print_str(va_list s)): This fucntion prints a string, or (null) if a nul pointer was passed.
• print_rev (prototype: int print_rev(va_list s)): This function prints a string in reverse.
• print_rot13 (prototype: int print_rot13(va_list s)): This function prints a string in rot13 format.

print_number_functions.c

This file contains functions that prints numbers in different formats. This functions returns the count of numbers printed. This functions are:

• print_integer (prototype: int print_integer(va_list i)): this function prints an integer number, from INT_MIN to INT_MAX.
• print_bin (prototype: int print_bin(va_list n)): this function converts an unsigned integer into a binary number and print it.
• print_hex_minus (prototype: int print_hex_minus(va_list num)): this function converts an integer into a hexadecimal number and print it. This version prints the hexadecimal in minus.
• print_hex_mayus (prototype: int print_hex_mayus(va_list num)): this function converts an integer into a hexadecimal number and print it. This version prints the hexadecimal in MAYUS.

auxiliar_functions.c

This file contains auxiliar function of print_integer.

• _print_rev (prototype: : prints an integer in reverse
• _abs: converts an integer in its absolute value

print_adress_function.c

This file contains functions that together prints an address.

• print_address (prototype: int print_address(va_list p)): recieves an unsigned long int. If it is 0, prints "(nil)", otherwise it prints a 0, an x and it calls the function hex_to_string.
• hex_to_string (prototype: int hex_to_string(unsigned long int number, int lw)): gets the unsigned long int and converts it to an hexadecimal number, which is stored in an array (in reverse) that is printed with the function _print_rev.

Specifications

This repository was made with the following authorized functions and macros:

write (man 2 write)
malloc (man 3 malloc)
free (man 3 free)
va_start (man 3 va_start)
va_end (man 3 va_end)
va_copy (man 3 va_copy)
va_arg (man 3 va_arg)

Authors

This repository was made by:

• Juan Sebastian Gonzalez Twitter: @juancho1141
• Juan Sebastian Perea Twitter: @JuanSePeBe95 IG: @sebaspbf