stan6453/printf

THE PRINTF PROJECT Introduction: The printf function sends formatted output to stdout. This project was curated for learning purposes by Stanley Ezechukwu and Sandra Nwogbo in the Holberton & Alx scholarship program Cohort 9.

The _printf() function returns the total number of characters printed to the stdout(excluding the null byte at the end of strings) after a successful execution.

If an output error is encountered, a negative value of -1 is returned.

The prototype of this function is: int _printf(const char format, ...);

This means that it has one mandatory format argument, and an extra number of arguments that can be none, or many.

Format of the format string

The format string is a character string starting and ending with double quotes. The format string is composed of zero or more directives; ordinary characters (not %), and conversion specifications, each of which results in fetching zero or more subsequent arguments.

Each conversion specification is introduced by the character % and ends with a conversion specifier. In between there may be (in this order):

Zero or more flags

An optional field width

An optional precision modifier

An optional length modifier

The flag characters

Flag Description

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 The code must be compiled this way:

*$ gcc -Wall -Werror -Wextra -pedantic .c

As a consequence, be careful not to push any c file containing a main function in the root directory of your project (you could have a test folder containing all your tests files including main functions)

The main files will include your main header file (main.h): #include main.h

Use & Example Prototype: int _printf(const char *format, ...); Use - General: _printf("format string", var1, var2, ...);

Examples:

Basic String: _printf("%s Hello, World!");`

Output: Hello, World! Print integers: _printf("This is an array element: arr[%d]:%c", 32, arr[32]);`

Output: This is an array element arr[32]:A Many other specifiers and flags were added and by combinig those the _printf() function generate a different ouput. The following list are the specifiers and flags allowed.

Specifiers Specifier Output Examples c Character y d or i Signed integer 1024, -1024 s String of characters Hello, world! b Binary Representation of unsigned integer. 01010110 u Unsigned integer 1024 o Unsigned octal 432 x Unsigned hexadecimal integer 3ca x Unsigned hexadecimal integer (uppercase) 3CA s String with hex-ascii value replacing special chars \x0A\x0A p Pointer address 0x403212 r Reversed string of characters dlroW olleH R ROT13 Translation of string Uryyb Flags flags Description

• Left-justify the output within the field width that was given; Right justification is the default (see width sub-specifier)

• Preceeds the result with a plus or minus sign (+ or -) even for positive numbers. By default, only negative numbers are preceded with a - sign. (space) If no sign is going to be written, a blank space is inserted before the value.

Used with o, x or X specifiers the value is preceeded with 0, 0x or 0X respectively for values different than zero.

0 Left-pads the number with zeroes (0) instead of spaces when padding is specified (see width sub-specifier).