Foundations - Low-level programming & Algorithm ― Hatching out by Julien Barbier, co-founder at Holberton School. Project to be done in teams of 2 people (your team: Oliyad Kebede, Kaleb Ayelaw)
- Write your own
printffunction.
- Allowed editors: vi, vim, emacs.
- All your files will be compiled on Ubuntu 14.04 LTS.
- Your programs and functions will be compiled with gcc 4.8.4 using the flags -Wall -Werror -Wextra and -pedantic.
- All your files should end with a new line.
- A README.md file, at the root of the folder of the project is mandatory.
- Your code should use the Betty style. It will be checked using betty-style.pl and betty-doc.pl.
- You are not allowed to use global variables.
- No more than 5 functions per file.
- In the following examples, the main.c files are shown as examples. You can use them to test your functions, but you don’t have to push them to your repo (if you do we won’t take them into account). We will use our own main.c files at compilation. Our main.c files might be different from the one shown in the examples.
- The prototypes of all your functions should be included in your header file called holberton.h
- Don’t forget to push your header file.
- All your header files should be include guarded.
- Note that we will not provide the_putchar function for this project
printf is the C language function to do format-ted printing. The same function is also available in PERL. The printf function sends formatted output to stdout. A custom _printf() for learning purposes was developed by cohort #9 students Jimmer and Edward Ortiz. _printf() function format string is a character string, beginning and ending in its initial shift state, if any. These arguments are placed using the percentage '%' operator
Secrets of printfby Don colton https://www.cypress.com/file/54761/download
- 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)
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 (holberton.h): #include holberton.h
Prototype: int _printf(const char *format, ...); Use - General: _printf("format string", var1, var2, ...);
Examples:
-
Basic String: _printf("%s Holberton", "Hello");`
- Output: Hello Holberton
-
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.
| Specifier | Output | Examples |
|---|---|---|
c |
Character | y |
d or i |
Signed integer | 1024, -1024 |
s |
String of characters | Hello Holberton |
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 |
| Flag | 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). |
| 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. |
* |
The width is not specified in the format string, but as an additional integer value argument preceding the argument that has to be formatted. |
| .Precision | Description |
|---|---|
.(number) |
For integer specifiers (d, i, o, u, x, X): precision specifies the minimum number of digits to be written. If the value to be written is shorter than this number, the result is padded with leading zeros. The value is not truncated even if the result is longer. A precision of 0 means that no character is written for the value 0. For s: this is the maximum number of characters to be printed. By default all characters are printed until the ending null character is encountered. If the period is specified without an explicit value for precision, 0 is assumed. |
| Modifier/Specifier | d & i |
u, o, x, X |
c |
s |
p |
|---|---|---|---|---|---|
none |
int | unsigned int | int | char pointer | void pointer |
h |
short int | unsigned short int | |||
l |
long int | unsigned long int |
| Name | Information | Relevant Files |
|---|---|---|
man_3_printf |
Man page of the _printf() function. | None |
holberton.h |
Header file with the data type struct, standard libraries and custom prototypes. | *.c compilation |
_printf.c |
Main printf function file. Calls other functions. | printf_(name of var).c file |
printf_37.c |
Contains percentage print function. | None |
printf_int.c |
Contains decimal and integer functions. | None |
printf_char.c |
Custom function for char data type. | None |
printf_sting.c |
Function that calls string type variable. | None |
printf_bin.c |
Function that gets the binary | None |
printf_oct.c |
Functions that returns octal number. | None |
printf_hex.c |
Calls hexadecimal numbers (lowercase). | None |
printf_HEX.c |
Calls hexadecimal numbers (Uppercase). | None |
printf_unsigned.c |
Returns an unisgined data type. | None |
printf_hex_aux.c |
Auxiliar function for hexadecimal specific functions (lowercase). | printf_exclusive_string.c |
printf_HEX_aux.c |
Auxiliar function hexadecimal specific functions (Uppercase). | printf_p.c |
printf_exclusive_string.c |
Returns a string and non readable characters are printed in hexadecimal numbers (Lowercase). | printf_hex_aux.c |
printf_srev.c |
Returns a string in reverse. | None |
printf_rot13.c |
Returns a string in Rot13. | None |
printf_str.c |
Auxiliar functions such as strlen and strcpy. | None |
_putchar.c |
Custom putchar function. | None |
Handle the following conversion specifiers:
- d
- i
- You don’t have to handle the flag characters
- You don’t have to handle field width
- You don’t have to handle precision
- You don’t have to handle the length modifiers
- b: the unsigned int argument is converted to binary
- u
- o
- x
- X
- You don’t have to handle the flag characters
- You don’t have to handle field width
- You don’t have to handle precision
- You don’t have to handle the length modifiers
- S : prints the string.
- Non printable characters "(0 < ASCII value < 32 or >= 127)" are printed this way: \x, followed by the ASCII code value in hexadecimal (upper case - always 2 characters)
7. How is the world ruled and led to war? Diplomats lie to journalists and believe these lies when they see them in print
- You don’t have to handle the flag characters
- You don’t have to handle field width
- You don’t have to handle precision
- You don’t have to handle the length modifiers
- +
- space
- #
- l
- h Conversion specifiers to handle: d, i, u, o, x, X
13. Every time that I wanted to give up, if I saw an interesting textile, print what ever, suddenly I would see a collection.
- r : prints the reversed string
- R: prints the rot13'ed string
- GitHub repository: printf