Ft_printf

Printf

Requirements

Program name: libftprintf.a

Turn in files: Makefile, *.h, */*.h, *.c, */*.c

Makefile: NAME, all, clean, fclean, re

External functs: malloc, free, write, va_start, va_arg, va_copy, va_end

Libft authorized: Yes

Description: Write a library that contains ft_printf(), a function that will mimic the original printf()

Here are the requirements:

• Don’t implement the buffer management of the original printf().
• Your function has to handle the following conversions: cspdiuxX%
• Your function will be compared against the original printf().
• You must use the command ar to create your library. Using the libtool command is forbidden.
• Your libftprintf.a has to be created at the root of your repository.

You have to implement the following conversions:

• %c Prints a single character.
• %s Prints a string (as defined by the common C convention).
• %p The void * pointer argument has to be printed in hexadecimal format.
• %d Prints a decimal (base 10) number.
• %i Prints an integer in base 10.
• %u Prints an unsigned decimal (base 10) number.
• %x Prints a number in hexadecimal (base 16) lowercase format.
• %X Prints a number in hexadecimal (base 16) uppercase format.
• %% Prints a percent sign.

Printf: 🔗 Details

Limits:

• Long long:

  • max : 9,223,372,036,854,775,807, Len 19 char
  • binary long long max: 0111111111111111111111111111111111111111111111111111111111111111, Len: 64 char

• Unsigned int max = 4294967295

• Int max = 2147483647;

• Int min = -2147483648;

Variadic Functions

header: #include <stdarg.h>

Variadic function adds flexibility to the program. It takes one fixed argument and then any number of arguments can be passed. The variadic function consists of at least one fixed variable and then an ellipsis(…) as the last parameter.

Syntax: int function_name(data_type variable_name, ...);

Create a va_list with: va_list name_of_list;

To use / iterate on the list:

• va_start(name_of_list, variable_name)

• va_end(name_of_list)

Methods	Description
va_start(va_list ap, argN)	This enables access to variadic function arguments. Where va_list will be the pointer to the last fixed argument in the variadic function. argN is the last fixed argument in the variadic function. From the above variadic function (function_name (data_type variable_name, …); ), variable_name is the last fixed argument making it the argN. Whereas va_list ap will be a pointer to argN (variable_name)
va_arg(va_list ap, type)	This one accesses the next variadic function argument. va_list ap is the same as above i.e a pointer to argN. type indicates the data type the va_list ap should expect (double, float, int etc.)
va_copy(va_list dest, va_list src)	This makes a copy of the variadic function arguments.
va_end(va_list ap)	This ends the traversal of the variadic function arguments.

Example:

// C program for the above approach

#include <stdarg.h>
#include <stdio.h>

// Variadic function to add numbers
int AddNumbers(int n, ...)
{
 int Sum = 0;

 // Declaring pointer to the
 // argument list
 va_list ptr;

 // Initializing argument to the
 // list pointer
 va_start(ptr, n);

 for (int i = 0; i < n; i++)

  // Accessing current variable
  // and pointing to next one
  Sum += va_arg(ptr, int);

 // Ending argument list traversal
 va_end(ptr);

 return Sum;
}

// Driver Code
int main()
{
 printf("\n\n Variadic functions: \n");

 // Variable number of arguments
 printf("\n 1 + 2 = %d ",
  AddNumbers(2, 1, 2));

 printf("\n 3 + 4 + 5 = %d ",
  AddNumbers(3, 3, 4, 5));

 printf("\n 6 + 7 + 8 + 9 = %d ",
  AddNumbers(4, 6, 7, 8, 9));

 printf("\n");

 return 0;
}

Variadic functions: 

 1 + 2 = 3 
 3 + 4 + 5 = 12 
 6 + 7 + 8 + 9 = 30

🔗 Details