ft_printf

A 42-school project to produce a reproduction of the printf function in C.

Key Considerations at Project Start:

The function is a variadic function, which means that it takes a variable number of arguments. Will need to use the appropriate variadic function macros and data types, such as "va_list" and "va_start", to correctly handle the variable number of arguments passed to this version of the "ft_printf" function.
The "printf" function is used to format and print data to the standard output stream (usually the screen), so will need to implement the necessary logic and formatting rules to properly output the data. This will involve parsing the format string and handling the various format specifiers that can be used to control the output, such as " %d" for decimal integers and " %s" for strings.
It is important to follow the same conventions and standards used by the existing implementation. This includes using the same function signature and return type, as well as adhering to the same formatting and behavior specified by the C standard.
It is important to make sure that the implementation behaves identically to the standard version in all cases. This will involve thorough testing and debugging to ensure that the implementation is correct and reliable.

Objective:

The goal of this project is to implement a custom version of the "printf" function from the Standard C Library, with the similar functionality and behavior as the standard version, specificially 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.

Bonus: • Manage any combination of the following flag characters: ’-0.’ and the field minimum width under all conversions. • - Value left adjusted on the field boundary. (Default is right justification). Padded with blanks. Overrides 0. • 0 Value should be zero padded. If precision is given with a numeric conversion, 0 flag ignored. • . (With number): min. characters to be printed. If min. characters exceeds the number, the result is padded with spaces. (Without number) : Precision character flag, defines the precision as to be in an additional inveger value argument that precedes the argument to be formatted. • Manage all the following flag characters: ’# +’ (Yes, one of them is a space) • # Value converted to alternative form. Multiple specifiers. • (Blank space) If no sign is written, a blank space is inserted before the value. • + Forces result to be preceded by + or - sign. Only negative numbers are preceeded by a -, by default.

Scope:

The scope of this project includes the implementation of the "printf" function, as well as any necessary supporting functions or data types. The project will not include the implementation of any additional formatting specifiers beyond those specified as part of the project, unless deemed neccesary as "hidden requirements" for the function of the ones defined in the brief.

Requirements:

In order to meet the objective of the project, the following requirements must be satisfied:

Have the same function signature and return type as the standard version.
Support all of the same formatting specifiers as the standard version (or at least as many designated in the brief).
Output the same formatted data as the standard version, given the same input.
Handle variable numbers of arguments using the appropriate variadic function macros and data types.

Design:

The design of the project will involve the following steps:

Familiarize with the existing implementation of the "printf" function, including its function signature, behavior, and supported formatting specifiers.
Write a skeleton implementation of the "printf" function that includes the necessary variadic function macros and data types to handle variable numbers of arguments.
Implement the logic for parsing the format string and handling the various format specifiers.
Test the implementation thoroughly to ensure that it behaves correctly and produces the same output as the standard "printf" function.
Refine and optimize the implementation as needed to improve performance and reliability.

Initial Phase

Divide required functions into sub-functions.
Identify pitfalls / common-issues in input sanitisation/processing.
Identify return values from standardlib Printf.
Consider flag order of prescidence and contradictive behaviours.