💢 ft_printf : A new headache was born.

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🏆 1337Cursus project :

The versatility of The printf function in C represents a great exercise in programming. This project is of MODERATE difficulty. It will enable you to discover variadic functions in C. The key to a successful ft_printf is a well-structured and good extensible code.

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🚫 ft_printf("%s\n", "When you light a candle, you also cast a shadow.");

🚫 ft_printf("%s\n", "What hurts you, blesses you. Darkness is your candle.");

🚫 ft_printf("%s\n", "Into the darkness they go, the wise and the lovely.");

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🎯 Mandatory :

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A small description of the required conversions :

%	Type
%c	Print a single character.
%s	Print a string of characters.
%p	The void * pointer argument is printed in hexadecimal.
%d	Print a decimal (base 10) number.
%i	Print an integer in base 10.
%u	Print an unsigned decimal (base 10) number.
%x	Print a number in hexadecimal (base 16, lowercase).
%X	Hex integer (uppercase).
%%	Just the %.

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🎯 Bonus :

Manage any combination of the following flags :

• -0. and minimum field width with all conversions.
• Manage all the following flags: # +(yes, one of them is a space).

🚩 Flags 🚩	❓
Num	(Number between % and the identifier) Minimum field width.
-	Left justify.
0	Field padded with 0's instead of blanks.
.	Precision.
+	Add a plus sign ('+') in the front of positive numeric conversions.
' '	Add a single space (' ') in the front of positive numeric conversions.
#	Add the corresponding prefix in front of x, X and o conversions.

This is how the embedded format tags are aligned :

Holder key	Prefix and justification flags *	Minimum Width *	Precision *	Conversion
%	- , 0 , + , ...	10, 5 , ...	., .10, .5, ...	c, d, i, s, ...

For %d and %i, the precision is the minimum number of digits to print.

For %s, the precision is the maximum field width.

🔻 To be aware of :

• flag '0' is ignored when flag '-' is present.
• flag '0' is ignored when flag '.' is present (%d e %i).
• flag '0' results in undefined behavior with '%c', '%s' and '%p'.
• flag '.' results in undefined behavior with '%c' and '%p'.

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🚧 Project Organization :

.
├── includes/
├── libft/
├── srcs/
├── Makefile

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Step 1️⃣ :

• I created a format structure inside my headerfile and also made some basic util typdefs :

typedef	struct s_fmt
{
	const char	*format;
	va_list		ap;
	size_t		i;
	size_t		counter;
}	t_fmt;

• Also a placeholder structure to stock all the informations about every placeholder that printf manages :

typedef	struct s_holder
{
	int	left_justify;
	char	*prefix;
	char	padding;
	int	width;
	int	precision;
	char	conversion;
	char	*argument;
	size_t	counter;	
}	t_holder;

Step 2️⃣ :

I created mandatory functions in my ft_printf.c file :

int ft_printf(const char *format, ...);

int ft_vprintf(const char *format, va_list ap);

DESCRIPTION :

The  functions in the printf() family produce output according to a format 
as described below.  The functions printf() and vprintf() write output to 
stdout, the standard output stream. 

PARAMETERS :

#1. The string format in which the output will be printed.
#2. ... The variadic arguments passed to the format string's placeholders. In 
the vprintf() function, the variadic argument are already passed as a 
va_list type.

RETURN VALUES :

Upon successful return, these functions return the number of characters printed.

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Step 3️⃣ :

I created functions responsible of initilizing both of my structures inside my ft_initializer.c file:

t_fmt *ft_initialize_fmt(const char *format, va_list ap);

t_holder *ft_initialize_holder(void);

FT_INITIALIZE_FMT!

DESCRIPTION :

Initializes the format struct with the string given and the va_list variable,
setting the initial values of both variables i and counter up to 0.

PARAMETERS :

#1. The string format in which the output will be printed.
#2. The variadic arguments list

RETURN VALUES :

The new, initialized variable struct format.

FT_INITIALIZE_HOLDER!

DESCRIPTION :

Initialize the holder struct that will retain the information of the 
placeholders flags and conversions.

PARAMETERS :

NONE.

RETURN VALUES :

The new, initialized variable struct holder.

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Step 4️⃣ :

I Created a function that will manage the format string, and unitializes the holder as well :

void ft_placeholder_manager(t_fmt *fmt);

DESCRIPTION :

The  ft_placeholders_manager() function manages whatever comes after the '%' char in the
ft_printf() function. It calls the ft_initializer() function for the 
format struct, as well as the ft_parsing() function that will eventually convert
the argument passed to the va_list into the holder struct. At the end, it
will print to the screen the converted string of the respective argument.

PARAMETERS :
#1. The t_format struct that holds information about the string to be formatted.

RETURN VALUES :

NONE.

Then i had to do some syntax analyzing (parsing) althrough the format string using the function ft_parsing() and its subfunctions "ft_flags_parser() ...".

void *ft_parsing(t_fmt *fmt, t_holder *holder);

DESCRIPTION :

The ft_parsing() function will take the format string from the index in which the
placeholder begins, and will attempt to analyze and organize its flags and 
conversors into a struct of type t_holder, using other parsing subfunctions.

PARAMETERS :

#1. The t_format struct that holds information about the string to be formatted.

RETURN VALUES :

It returns the t_holder variable that holds all the information about that particular placeholder.

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🏆 Final Score :

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