0x11. C - printf

In collaboration with Gideon Mutai

Concepts

For this project, we expect you to look at these concepts:

Group Projects

Pair Programming - How To

Flowcharts

Technical Writing

Printf function brief - What to know to create your own Printf function

All about Team Projects + Pairings + FAQ (A must read)

Background Context

Write your own printf function.

Resources

Read or watch:

Secrets of printf

Group Projects concept page (Don’t forget to read this)

Flowcharts concept page

man or help:

> printf (3)

More Info

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)

Compilation

Your code will be compiled this way:

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

As a consequence, be careful not to push any c file containing a main function in the root directory of your project (you could have a test folder containing all your tests files including main functions)

Our main files will include your main header file (main.h): #include main.h

You might want to look at the gcc flag -Wno-format when testing with your _printf and the standard printf. Example of test file that you could use:

Test file

alex@ubuntu:~/c/printf$ cat main.c 
            #include <limits.h>
            #include <stdio.h>
            #include "main.h"
    
            /**
            * main - Entry point
            *
            * Return: Always 0
            */
    
            int main(void)
            {
                int len;
        int len2;
        unsigned int ui;
        void *addr;

        len = _printf("Let's try to printf a simple sentence.\n");
        len2 = printf("Let's try to printf a simple sentence.\n");
        ui = (unsigned int)INT_MAX + 1024;
        addr = (void *)0x7ffe637541f0;
        _printf("Length:[%d, %i]\n", len, len);
        printf("Length:[%d, %i]\n", len2, len2);
        _printf("Negative:[%d]\n", -762534);
        printf("Negative:[%d]\n", -762534);
        _printf("Unsigned:[%u]\n", ui);
        printf("Unsigned:[%u]\n", ui);
        _printf("Unsigned octal:[%o]\n", ui);
        printf("Unsigned octal:[%o]\n", ui);
        _printf("Unsigned hexadecimal:[%x, %X]\n", ui, ui);
        printf("Unsigned hexadecimal:[%x, %X]\n", ui, ui);
        _printf("Character:[%c]\n", 'H');
        printf("Character:[%c]\n", 'H');
        _printf("String:[%s]\n", "I am a string !");
        printf("String:[%s]\n", "I am a string !");
        _printf("Address:[%p]\n", addr);
        printf("Address:[%p]\n", addr);
        len = _printf("Percent:[%%]\n");
        len2 = printf("Percent:[%%]\n");
        _printf("Len:[%d]\n", len);
        printf("Len:[%d]\n", len2);
        _printf("Unknown:[%r]\n");
        printf("Unknown:[%r]\n");
        return (0);
    }

alex@ubuntu:~/c/printf$ gcc -Wall -Wextra -Werror -pedantic -std=gnu89 -Wno-format *.c
alex@ubuntu:~/c/printf$ ./printf
        Let'st try to printf a simple sentence.
        Let's try to printf a simple sentence.

        Length:[39, 39]
        Length:[39, 39]
        Negative:[-762534]
        Negative:[-762534]
        Unsigned:[2147484671]
        Unsigned:[2147484671]
        Unsigned octal:[20000001777]
        Unsigned octal:[20000001777]
        Unsigned hexadecimal:[800003ff, 800003FF]
        Unsigned hexadecimal:[800003ff, 800003FF]
        Character:[H]
        Character:[H]
        String:[I am a string !]
        String:[I am a string !]
        Address:[0x7ffe637541f0]
        Address:[0x7ffe637541f0]
        Percent:[%]
        Percent:[%]
        Len:[12]
        Len:[12]
        Unkn
        own:[%r]
        Unknown:[%r]
alex@ubuntu:~/c/printf$