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printf Project

March / 2020

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The printf project is the coding of a function named "_printf()" that imitates to "printf()". This C language function is a powerful device for printing numbers and other things stored in variables. Located in the stdio.h library. You can find some of the basic features and functions in the manual 3 of "printf()".

_printf() is a function that performs formatted output conversion and print data, but what means that. Please, read about the variadic functions and go back later.

Its prototype was defined following:

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

Where format contains a string that will be print. This strings is composed by n arguments that will be replace by n tags definied inside the string.

Following, the variadic function format tags prototype is:

   %[flags][length]specifier

Return value is the amount of chars printed (program successfully), see this tables:

Specifier	Output
c	Character
d or i	Signed decimal integer
s	String of characters
b	unsigned decimal integer in binary
u	unsigned decimal integer
o	unsigned decimal integer in octal
x	unsigned decimal integer in hexadecimal lower case
X	unsigned decimal integer in hexadecimal upper case
p	address as hexadecimal (base 16) lower case
S	String including Non printable characters
r	reversed string
R	string in rot13
%	Character

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Examples

1. Printing the string "Example":

• Use: _printf("%s", "Example");
• Output: Holberton.

2. print the singular character 'e':

• Use: _printf("%c", e);
• Output: e

3. Print the decimal number 5:

• Use: _printf("%d", 5);
• Output: 5

4. Print the int number -98:

• Use: _printf("%i", -98);
• Output: -98

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File Functions

_printf.c

Our printf function the Performs formatted Output Conversion And Print Data.

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holberton.h

Header file. Include all prototypes functions used

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Task files

• task_0.c

int print_c(va_list c) /* prints a char */

int print_s(va_list s) /* prints a string */

• task_1.c

int print_i(va_list i) /* prints an integer */

int print_d(va_list d) /* prints a decimal */

• task_3.c

int print_b(va_list b) /* prints an unsigned integer in binary (base 2) */

• task_4.c

int print_u(va_list u); /* prints an unsigned integer */

int print_o(va_list o); /* prints an unsigned integer in octal (base 8) */

int print_x(va_list x); /* prints an unsigned integer in hexadecimal (base 16) */

int print_X(va_list X); /* prints an unsigned integer in hexadecimal (base 16) */

• task_6.c

static unsigned long power(unsigned int x, unsigned int y) /* calculates an exponent */

int print_p(va_list p); /* prints a hexadecimal address (0x base 16) */

• task_7.c

int print_S(va_list S); /* prints a string with Non printable characters (ASCII code value hexadecimal) */

• task_14.c

print_r(va_list r); /* prints a reverse string */

• task_15.c

int print_R(va_list R); /* prints a string in rot13 */

Return values

On success returns an integer number of symbols printed not counting \0 for the string.

On failure returns error number (-1)

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Flowchart

• _printf

• verify_type

Team Project

It's a collaboration between Crispthofer Rincon & Santiago Martinez, students (from cohort 11 - january 2020) of Software Engineering at Holberton School

Waiting for you in Holberton School Campus Cali, Colombia