0x06-pointers_arrays_strings

0x06. C - More pointers, arrays and strings

Learning Objectives

At the end of this project, you are expected to be able to explain to anyone, without the help of Google:

General

• What are pointers and how to use them
• What are arrays and how to use them
• What are the differences between pointers and arrays
• How to use strings and how to manipulate them
• Scope of variables

Copyright - Plagiarism

• You are tasked to come up with solutions for the tasks below yourself to meet with the above learning objectives.
• You will not be able to meet the objectives of this or any following project by copying and pasting someone else’s work.
• You are not allowed to publish any content of this project.
• Any form of plagiarism is strictly forbidden and will result in removal from the program.

Requirements

General

• Allowed editors: vi, vim, emacs
• All your files will be compiled on Ubuntu 20.04 LTS using gcc, using the options -Wall -Werror -Wextra -pedantic -std=gnu89
• 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
• You are not allowed to use the standard library. Any use of functions like printf, puts, etc… is forbidden
• You are allowed to use _putchar
• You don’t have to push _putchar.c, we will use our file. If you do it won’t be taken into account
• 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 and the prototype of the function _putchar should be included in your header file called main.h
• Don’t forget to push your header file

Tasks

0-strcat.c

Write a function that concatenates two strings.

• Prototype: char *_strcat(char *dest, char *src);
• This function appends the src string to the dest string, overwriting the terminating null byte (\0) at the end of dest, and then adds a terminating null byte
• Returns a pointer to the resulting string dest FYI: The standard library provides a similar function: strcat. Run man strcat to learn more.

1-strncat.c

Write a function that concatenates two strings.

• Prototype: char *_strncat(char *dest, char *src, int n);
• The _strncat function is similar to the _strcat function, except that it will use at most n bytes from src; and src does not need to be null-terminated if it contains n or more bytes
• Return a pointer to the resulting string dest FYI: The standard library provides a similar function: strncat. Run man strncat to learn more.

2-strncpy.c

Write a function that copies a string.

• Prototype: char *_strncpy(char *dest, char *src, int n);
• Your function should work exactly like strncpy FYI: The standard library provides a similar function: strncpy. Run man strncpy to learn more.

3-strcmp.c

Write a function that compares two strings.

• Prototype: int _strcmp(char *s1, char *s2);
• Your function should work exactly like strcmp FYI: The standard library provides a similar function: strcmp. Run man strcmp to learn more.

4-rev_array.c

Write a function that reverses the content of an array of integers.

• Prototype: void reverse_array(int *a, int n);
• Where n is the number of elements of the array

5-string_toupper.c

Write a function that changes all lowercase letters of a string to uppercase.

• Prototype: char *string_toupper(char *);

6-cap_string.c

Write a function that capitalizes all words of a string.

• Prototype: char *cap_string(char *);
• Separators of words: space, tabulation, new line, ,, ;, ., !, ?, ", (, ), {, and }

7-leet.c

Write a function that encodes a string into 1337.

• Letters a and A should be replaced by 4
• Letters e and E should be replaced by 3
• Letters o and O should be replaced by 0
• Letters t and T should be replaced by 7
• Letters l and L should be replaced by 1
• Prototype: char *leet(char *);
• You can only use one if in your code
• You can only use two loops in your code
• You are not allowed to use switch
• You are not allowed to use any ternary operation

100-rot13.c

Write a function that encodes a string using rot13.

• Prototype: char *rot13(char *);
• You can only use if statement once in your code
• You can only use two loops in your code
• You are not allowed to use switch
• You are not allowed to use any ternary operation

101-print_number.c

Write a function that prints an integer.

• Prototype: void print_number(int n);
• You can only use _putchar function to print
• You are not allowed to use long
• You are not allowed to use arrays or pointers
• You are not allowed to hard-code special values

102-magic.c

Add one line to this code, so that the program prints a[2] = 98, followed by a new line.

• You are not allowed to use the variable a in your new line of code
• You are not allowed to modify the variable p
• You can only write one statement
• You are not allowed to use ,
• You are not allowed to code anything else than the line of expected line of code at the expected line
• Your code should be written at line 19, before the ;
• Do not remove anything from the initial code (not even the comments) and don’t change anything but the line of code you are adding (don’t change the spaces to tabs!)
• You are allowed to use the standard library

103-infinite_add.c

Write a function that adds two numbers.

• Prototype: char *infinite_add(char *n1, char *n2, char *r, int size_r);
• Where n1 and n2 are the two numbers
• r is the buffer that the function will use to store the result
• size_r is the buffer size
• The function returns a pointer to the result
• You can assume that you will always get positive numbers, or 0
• You can assume that there will be only digits in the strings n1 and n2
• n1 and n2 will never be empty
• If the result can not be stored in r the function must return 0

104-print_buffer.c

Write a function that prints a buffer.

• Prototype: void print_buffer(char *b, int size);
• The function must print the content of size bytes of the buffer pointed by b
• The output should print 10 bytes per line
• Each line starts with the position of the first byte of the line in hexadecimal (8 chars), starting with 0
• Each line shows the hexadecimal content (2 chars) of the buffer, 2 bytes at a time, separated by a space
• Each line shows the content of the buffer. If the byte is a printable character, print the letter, if not, print .
• Each line ends with a new line \n
• If size is 0 or less, the output should be a new line only \n
• You are allowed to use the standard library
• The output should look like the following example, and formatted exactly the same way

Amen