very important points
#include <stdarg.c>
//we include this libary to use va_list and va_end
char oussama(int num , ...); //we could this function : varg function take a lot of argument
// if we work at varg funtions we have to initilaze macors
// first macro is va_list he pointed to fisrt argument ( ... ) // arg he play on this example count of argument we need va_list arg ; // this is prototype of valist macros // is not variable !!!!!
//second macro we have va_start //this macro is help to find start of arguments we need and use it //we give two arguments is this macro //fisr arg : is this macro we creat before creat va_start ,because he need to know first point to start // first arg pointed
// second num : is this parametre we creat in the start function in this example is num // he play pointe to stop // he take last parametre we creat in this example is num
// in another example if we have 3 parametre //in this example num 3 is the last parametre we creat sooo is second parametre in va_start void ouss(int num1, int num2 , int num3 , ...);
va_start (arg ,num); // brrooooooo is not variable xd
//third macro we have is is va_arg :) //this macro is very importatnt because he move between our arguments he pointed a first argument and second and third ..... //he need two argument // first is arg : argument we need to pointed to group of atgumentswe have we help to pointed a second arg we need // second is int : int this exapmle we have type int , in another examples we found a lot of type(char , int float ....) ,on this example we need int becouse we need to creat a lot //of argument on type int ::: couse agaain we need to move in anther argument by 4 bythe :;; sooooo we move 4byte on 4byte in this exemple in another exapmle we found char or flot sooo that its va_arg(arg,int);
//in the last macro we have ve_end thats meens end of argumnets sooo end of our function // we have a start in same time we have end // we have a argumnent is arg // arg : is macro we creat in va_list //we type va_end (arg) to say our funtion that is end of this macro so stop baliz va_end(arg);
//thts sit i wish you undrstand this file so tnx gg //
https://github.com/Abaker-Hype/42-Cursus-Tester
A partial reimplementation of the printf in C. Handles only the following conversions.
| Conversion | Short Description |
|---|---|
| %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), with lowercase. |
| %X | Print a number in hexadecimal (base 16), with uppercase. |
| %% | Print a percent sign. |
format of va_list : typedef struct { unsigned int gp_offset; unsigned int fp_offset; void *overflow_arg_area; void *reg_save_area; } va_list[1];
overflow_arg_area : This pointer is used to fetch arguments passed on the stack. It is initialized with the address of the first argument passed on the stack, if any, and then always updated to point to the start of the next argument on the stack.
gp_offset The element holds the offset in bytes from reg_save_area to the place where the next available general purpose argument register is saved. In case all argument registers have been exhausted, it is set to the value 48 (6 * 8).
fp_offset : The element holds the offset in bytes from reg_save_area to the place where the next available floating point argument register is saved. In case all argument registers have been exhausted, it is set to the value 304 (6 * 8 + 16 * 16).
to more inforamtions : https://stackoverflow.com/questions/4958384/what-is-the-format-of-the-x86-64-va-list-structure
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