#_printf

Hello and welcome to our first group project, we're replicating the printf() function from the C Standard Library.

##Functionality

The printf() function takes input text and displays it on screen as stdout. It also uses format specifiers to display different variables previoulsy defined. For this we need format specifiers. To finish up, we have our text displayed on screen and a count of bytes printed.

The syntax is as follows:

_printf(const char *format, ...);

Example:

_printf("Hola %s\n", "Mundo");

Output:

Hola Mundo

In the above example, we use the format specifier %s, which is defined for strings. To make it work we need to detect the special character '%' and the following character, in this case the letter 's'. Then, we call our function to iterate a string, let's call it print_string(char *c); Then, we redirect the output of our print_string() function to our _printf() function, ending with the desired output.

Steps:

1. Pass in formatted text and variables for specifiers
2. Define iterators, flags and list to retrieve and manipulate input.
3. Verify that input exists, i.e something is passed into the function parameters.
4. Iterate the text and print it character by character, count bytes.
5. if there are any format specifiers, detect them and retrieve it's corresponding value from list.

Library

For our format specifiers to work properly, we need functions that take input and process it to display our desired output. The way we have to relate our _printf() program to these other functions is through a static library. We have all our files within the same directory and a library file with format .h that contains our function prototypes. Then the compiler takes care of calling our functions by matching the prototypes to our actual files.

Chart of specifiers and related functions:

Specifier	Variable assigned	Function prototype	Description
%%	N/A	_putchar(char c);	Prints special character '%'
%c	Char	_putchar(char c);	Prints one character
%s	String	print_str(char *c);	Prints string
%d	Integer	print_int(long int num);	Prints integer
%i	Integer	print_int(long int num);	Prints integer
%u	Integer	print_unt(long int num);	Prints integer without sign
%b	Unsigned Integer	print_bin(unsigned long int num);	Prints integer in binary
%o	Unsigned Integer	print_oct(unsigned long int num);	Prints integer in octal
%x	Unsigned Integer	print_hexlow(unsigned long int num);	Prints integer in lowercase hexadecimal
%X	Unsigned Integer	print_hex(unsigned long int num);	Prints integer in uppercase hexadecimal
%S	String	print_Str(char *c);	Prints string, special characters printed with their ASCII code in binary
%p	Void Pointer	print_ptr(void *ptr);	Prints address where pointer points to
%R	String	print_rot13(char *c);	Prints string in rot13 format
%r	String	print_rev(char *c);	Prints string reversed

##Flowchart

Ayrton Coelho, Marcelo Arbiza.