0x05-pointers_arrays_strings

C - Pointers, arrays and strings

In this project, I learned about what and how to use pointers and arrays and the differences between the two as well as how to use and manipulate strings in C.

Header File 📁

• main.h: Header file containing prototypes for all functions written in the project.

File	Prototype
0-reset_to_98.c	void reset_to_98(int *n);
1-swap.c	void swap_int(int *a, int *b);
2-strlen.c	int _strlen(char *s);
3-puts.c	void _puts(char *str);
4-print_rev.c	void print_rev(char *s);
5-rev_string.c	void rev_string(char *s);
6-puts2.c	void puts2(char *str);
7-puts_half.c	void puts_half(char *str);
8-print_array.c	void print_array(int *a, int n);
9-strcpy.c	char *_strcpy(char *dest, char *src);
100-atoi.c	int _atoi(char *s);

Tasks 📃

• 0. 98 Battery st.

  • 0-reset_to_98.c: C function that takes a pointer to an int as a parameter and updates the value it points to to 98.

• 1. Don't swap horses in crossing a stream

  • 1-swap.c: C function that swaps the value of two integers.

• 2. This report, by its very length, defends itself against the risk of being read

  • 2-strlen.c: C function that returns the length of a string.

• 3. I do not fear computers. I fear the lack of them

  • 3-puts.c: C function that prints a string, followed by a new line, to stdout.

• 4. I can only go one way. I've not got a reverse gear

  • 4-print_rev.c: C function that prints a string, in reverse, followed by a new line.

• 5. A good engineer thinks in reverse and asks himself about the stylistic consequences of the components and systems he proposes

  • 5-rev_string.c: C function that reverses a string.

• 6. Half the lies they tell about me aren't true

  • 6-puts2.c: C function that prints every other character of a string, followed by a new line.

• 7. Winning is only half of it. Having fun is the other half

  • 7-puts_half.c: C function that prints the second half of a string, followed by a new line.

• 8. Arrays are not pointers

  • 8-print_array.c: C function that prints an input n elements of an array of integers, followed by a new line.
    • Numbers are separated by a comma followed by a space.
    • Numbers are displayed in the same order as they are stored in the array.

• 9. strcpy

  • 9-strcpy.c: C function that copies the string pointed to by src, including the terminating null byte (\0), to the buffer pointed to by dest.
    • Returns the pointer to dest.

• 10. Great leaders are willing to sacrifice the numbers to save the people. Poor leaders sacrifice the people to save the numbers

  • 100-atoi.c: C function that converts a string to an integer without using long, new variable arrays, or hard-coded special values, as follows:
    • The number in the string can be preceded by an infinite number of characters.
    • Takes into account all + and - signs before the number.
    • If there are no numbers in the string, the function returns 0.

• 11. Don't hate the hacker, hate the code

  • 101-keygen.c: C program that generates random valid passwords for the program 101-crackme.