0x06-pointers_arrays_strings

0x06. C - More pointers, arrays and strings

Learning objectives for this project:

• 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

Tests ✔️

• tests: Tests files. Provided by Holberton School.

Helper File 🙌

• _putchar.c: C function that writes a character to stdout. Provided by Holberton School.

Header File 📁

• main.h: Header file containing prototypes for all programs written in this project.

File	Prototype
0-strcat.c	char *_strcat(char *dest, char *src);
1-strncat.c	char *_strncat(char *dest, char *src, int n);
2-strncpy.c	char *_strncpy(char *dest, char *src, int n);
3-strcmp.c	int _strcmp(char *s1, char *s2);
4-rev_array.c	void reverse_array(int *a, int n);
5-string_toupper.c	char *string_toupper(char *);
6-cap_string.c	char *cap_string(char *);
7-leet.c	char *leet(char *);
8-rot13.c	char *rot13(char *);
100-print_number.c	void print_number(int n);
102-infinite_add.c	char *infinite_add(char *n1, char *n2, char *r, int size_r);
103-print_buffer.c	void print_buffer(char *b, int size);

Tasks 📃

• 0. strcat

  • 0-strcat.c: C function that concatenates two strings.
    • Adds a terminating null byte at end.

• 1. strncat

  • 1-strncat.c: C function that concatenates two strings using at most an inputted number of bytes.
    • Adds a terminating null byte at end, unless source string is longer than maximum byte number.

• 2. strncpy

  • 2-strncpy.c: C function that copies a string, including the terminating null byte, using at most an inputted number of bytes.
    • If the length of the source string is less than the maximum byte number, the remainder of the destination string is filled with null bytes.
    • Works identically to the standard library function strncpy.

• 3. strcmp

  • 3-strcmp.c: C function that compares two strings.
    • Returns the difference in bytes at point of difference.
    • Works identically to the standard library function strcmp.

• 4. I am a kind of paranoid in reverse. I suspect people of plotting to make me happy

  • 4-rev_array.c: C function that reverses the content of an array of integers.

• 5. Always look up

  • 5-string_toupper.c: C function that changes all lowercase letters of a string to uppercase.

• 6. Expect the best. Prepare for the worst. Capitalize on what comes

  • 6-cap_string.c: C function that capitalizes all words of a string.

• 7. Mozart composed his music not for the elite, but for everybody

  • 7-leet.c: C function that encodes a string into 1337, without switch or ternary operations and using only one if and two loops.
    • Letters a and A are replaced by 4.
    • Leters e and E are replaced by 3.
    • Letters o and O are replaced by 0.
    • Letters t and T are replaced by 7.
    • Letters l and L are replaced by 1.

• 8. rot13

  • 8-rot13.c: C function that encodes a string to rot13, without switch or ternary operations and using only one if and two loops.

• 9. Numbers have life; they're not just symbols on paper

  • 100-print_number.c: C function that prints an integer without using long, arrays, pointers, or hard-coded special values.

• 10. A dream doesn't become reality through magic; it takes sweat, determination and hard work

  • 101-magic.c: C program that prints a[2] = 98 using pointer magic.
    • Completion of this source code.

• 11. It is the addition of strangeness to beauty that constitutes the romantic character in art

  • 102-infinite_add.c: C function that adds two numbers stored in strings to a buffer.
    • Assumes that strings are never empty and that numbers will always be positive, or 0.
    • Assumes there are only digits stored in the number strings.
    • If result can be stored in the buffer, returns a pointer to the result.
    • If result cannot be stored in the buffer, returns 0.

• 12. Noise is a buffer, more effective than cubicles or booth walls

  • 103-print_buffer.c: C function that prints the content of an inputted number of bytes from a buffer.
    • Prints 10 bytes per line.
    • Starts with the position of the first byte 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. Prints the byte if it is printable; if not, prints ..
    • Each line ends with a new line \n.
    • If the inputted byte size is 0 or less, the function only prints a new line.