_printf

About

This project is a custom implementation of C's printf function to do formatted printing. It is entirely written in C.

Syntax:

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

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Table of Content

• About
• Rules
• Authorized Resources
• Capabilities
• Usage
  • Requirements
  • Samples
• Authors

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Rules

• All files to be compiled on Ubuntu 20.04 LTS using gcc, using the options -Wall -Werror -Wextra -pedantic -std=gnu89.
• Code should use Betty style
• No global variables
• No more than 5 functions per file
• All header files should be include-guarded
• All files should end with a new line

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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)

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Capabilities of this implementation

The _printf mimics C's printf to format outputs according to the following non-custom conversion specifiers:

• c for characters
• s for strings
• d for decimal integers
• i for integers
• u for unsigned integers
• o for octal numbers
• x for lowercase hexadecimal numbers
• X for uppercase hexadecimal numbers
• p for addresses

In addition to the above specifiers, _printf is also capable of handling the following custom conversion specifiers:

• b prints the binary of an unsigned int
• S prints a string, including the ASCII code values (in HEX) of non-printable characters, prepended with \x.
• r prints a string in reverse.
• R prints the ROT-13 cypher of a string.

More features and capabilities to be added later.

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Usage

Requirements

• Ubuntu 20.04 LTS
• GCC compiler

The source files to be compiled using -Wall -Werror -Wextra -pedantic -std=gnu89 flags. The samples below illustrate the usage and compilation.

Samples

Below is a sample main file showcasing the various uses of _printf:

/* filename: main.c */
#include "main.h"
#include <stdio.h>
#include <limits.h>

int main(void)
{
 int len;
 unsigned int ui;
 void *addr;
 char *tst;
 int num;

 num = 32978;
 ui = (unsigned int) INT_MAX + 1024;
 addr = (void *) 0x7ffe637541f0;
 tst = "the quick brown fox jumps over the lazy dog";

 len = _printf("Let's try to printf a simple sentence.\n\n");

 _printf("Length:[%d, %i]\n\n", len, len);

 _printf("Negative:[%d]\n\n", -762534);

 _printf("Unsigned:[%u]\n\n", ui);

 _printf("Unsigned octal:[%o]\n\n", ui);

 _printf("Unsigned hexadecimal:[%x, %X]\n\n", ui, ui);

 _printf("Character:[%c]\n\n", 'A');

 _printf("String:[%s]\n\n", "I am a string !");

 _printf("Address:[%p]\n\n", addr);

 _printf("Percent:[%%]\n\n");

 _printf("%S\n\n", "Best\nSchool");

 _printf("%i in binary is %b\n", num, num);
 _printf("The value of num variable is %i and its address is %p\n\n", num, &num);

 _printf("%d%% of %d == %d%% of %d\n\n", 80, 50, 50, 80);

 _printf("%s in reverse is: %r\n\n", "strawberry", "strawberry");

 _printf("%s\n", tst);
 _printf("Reverse: %r\n", tst);
 _printf("ROT-13 cypher: %R\n", tst);

 return (0);
}

When compiled and run:

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

Length:[40, 40]

Negative:[-762534]

Unsigned:[2147484671]

Unsigned octal:[20000001777]

Unsigned hexadecimal:[800003ff, 800003FF]

Character:[A]

String:[I am a string !]

Address:[0x7ffe637541f0]

Percent:[%]

Best\x0ASchool

32978 in binary is 1000000011010010
The value of num variable is 32978 and its address is 0x7ffe3773defc

80% of 50 == 50% of 80

strawberry in reverse is: yrrebwarts

the quick brown fox jumps over the lazy dog
Reverse: god yzal eht revo spmuj xof nworb kciuq eht
ROT-13 cypher: gur dhvpx oebja sbk whzcf bire gur ynml qbt

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Authors

Ian Duncan

Esau Obuong