Printf

• Printf project, part of alx swe program

What is Printf

• printf() is a predefined function from stdio header file
• It's used to write formatted output to stdout
• Syntax

printf("Hello"); //outputs: Hello
printf("Hi my name is %s\n", "Tony"); //outputs: Hi my name is Tony

Available Features

• Currently our _printf() functions can handle the following conversion specifiers
• Custom conversion specifiers do not exist on the original printf

Specifier	Output	custom or non-custom
c	Character	non-custom
d or i	Signed integer	non-custom
s	String of characters	non-custom
b	Binary Representation of unsigned integer	non-custom
u	Unsigned integer	non-custom
o	Unsigned octal	non-custom
x	Unsigned hexadecimal integer	non-custom
X	Unsigned hexadecimal integer (uppercase)	non-custom
S	String with hex-ascii value replacing special chars	custom
p	Pointer address	custom
r	Reversed string of characters	custom
R	ROT13 Translation of string	custom

• It's also optimized to handle printing out characters once each 1 KB (1024 Byte) (check _putchar.c for reference)
• It can also handle the following flags

Flag	Description
-	Left-justify the output within the field width that was given; Right justification is the default (see width sub-specifier).
+	Precedes the result with a plus sign 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 hexadecimal and Octal specifiers to add a 0 (octal) or 0x (0X if used with %X)(hexadecimal) before printing the value of the number

• It's also implemented to handle the following length modifiers

Length modifier	Description
h	For Long Integers and unsigned long numbers
l	For short integers and unsigned short numbers

• It contains Field Width handling

Width	Description
(number)	Minimum number of characters to be printed. If the value to be printed is shorter than this number, the result is padded with blank spaces. The value is not truncated even if the result is larger.

Usage & Example

Function Prototype : int _printf(const char *format, ...);

Here's an example main.c file for testing out the function

#include <limits.h>
#include <stdio.h>
#include "main.h"

/**
 * main - Entry point
 *
 * Return: Always 0
 */
int main(void)
{
    int len;
    int len2;
    unsigned int ui;
    void *addr;

    len = _printf("Let's try to printf a simple sentence.\n");
    len2 = printf("Let's try to printf a simple sentence.\n");
    ui = (unsigned int)INT_MAX + 1024;
    addr = (void *)0x7ffe637541f0;
    _printf("Length:[%d, %i]\n", len, len);
    printf("Length:[%d, %i]\n", len2, len2);
    _printf("Negative:[%d]\n", -762534);
    printf("Negative:[%d]\n", -762534);
    _printf("Unsigned:[%u]\n", ui);
    printf("Unsigned:[%u]\n", ui);
    _printf("Unsigned octal:[%o]\n", ui);
    printf("Unsigned octal:[%o]\n", ui);
    _printf("Unsigned hexadecimal:[%x, %X]\n", ui, ui);
    printf("Unsigned hexadecimal:[%x, %X]\n", ui, ui);
    _printf("Character:[%c]\n", 'H');
    printf("Character:[%c]\n", 'H');
    _printf("String:[%s]\n", "I am a string !");
    printf("String:[%s]\n", "I am a string !");
    _printf("Address:[%p]\n", addr);
    printf("Address:[%p]\n", addr);
    len = _printf("Percent:[%%]\n");
    len2 = printf("Percent:[%%]\n");
    _printf("Len:[%d]\n", len);
    printf("Len:[%d]\n", len2);
    _printf("Unknown:[%r]\n");
    printf("Unknown:[%r]\n");
    return (0);
}

Contributors

• Tony | X | LinkedIn
• George | X | LinkedIn

Resources

Strings

• Passing NULL to printf

Buffer

• Write Documentation
• write function: is there a way to write only a part of the buffer?
• Static Variables in C
• What are the default values of static variables in C?