0x11. C - printf

C Group project

By: Julien Barbier, co-founder & CEO

Concepts:

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

Background Context:

Resources:

Secrets of printf
Group Projects concept page (Don’t forget to read this)
Flowcharts concept page

GitHub:

There should be one project repository per group. The other members do not fork or clone the project to ensure only one of the team has the repository in their github account otherwise you risk scoring 0%

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:

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

TASKS:

0. I'm not going anywhere. You can print that wherever you want to. I'm here and I'm a Spur for life

Write a function that produces output according to a format.

Prototype: int _printf(const char *format, ...);
Returns: the number of characters printed (excluding the null byte used to end output to strings)
write output to stdout, the standard output stream
format is a character string. The format string is composed of zero or more directives. See man 3 printf for more detail. You need to handle the following conversion specifiers:
- c
- s
- %
You don’t have to reproduce the buffer handling of the C library printf function
You don’t have to handle the flag characters
You don’t have to handle field width
You don’t have to handle precision
You don’t have to handle the length modifiers

1. Education is when you read the fine print. Experience is what you get if you don't

Handle the following conversion specifiers:

d
i
You don’t have to handle the flag characters
You don’t have to handle field width
You don’t have to handle precision
You don’t have to handle the length modifiers

2. With a face like mine, I do better in print

Handle the following custom conversion specifiers:

b: the unsigned int argument is converted to binary

3. What one has not experienced, one will never understand in print

Handle the following conversion specifiers:

u
o
x
X
You don’t have to handle the flag characters
You don’t have to handle field width
You don’t have to handle precision
You don’t have to handle the length modifiers

4. Nothing in fine print is ever good news

Use a local buffer of 1024 chars in order to call write as little as possible

5. My weakness is wearing too much leopard print

Handle the following custom conversion specifier:

S : prints the string.
Non printable characters (0 < ASCII value < 32 or >= 127) are printed this way: \x, followed by the ASCII code value in hexadecimal (upper case - always 2 characters)