README.md

0x05. C - Pointers, arrays and strings.

Resources

• Read the resources from the previous project; 0x05. C - Pointers, arrays and strings.

Tasks

0. strcat : A C function program 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.
   • Read more on strcat here.
   • Compile the code this way: gcc -Wall -pedantic -Werror -Wextra -std=gnu89 0-main.c 0-strcat.c -o 0-strcat
1. strncat : A C function program 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.
   • Compile the code this way: gcc -Wall -pedantic -Werror -Wextra -std=gnu89 1-main.c 1-strncat.c -o 1-strncat
2. strncpy : A C function program 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.
   • Compile the code this way: gcc -Wall -pedantic -Werror -Wextra -std=gnu89 2-main.c 2-strncpy.c -o 2-strncpy
3. strcmp : A C function program 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.
   • Read an example here to understand
     • Remember:
       • The strcmp returns the following;
         • 0 if s1 and s2 are equal
         • Negative integer if the stopping character in s1 was less than the stopping character in s2
         • Positive integer if the stopping character in s1 was greater than the stopping character in s2
       • So when we compare we will only check the difference of the first character found between s1 and s2, break the array iteration and return the difference.
   • Compile the code this way: gcc -Wall -pedantic -Werror -Wextra -std=gnu89 3-main.c 3-strcmp.c -o 3-strcmp
4. I am a kind of paranoid in reverse. I suspect people of plotting to make me happy : A C function program 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.
   • Read an example here on how to swap
   • n is the number of elements in the array Read here for more information.
   • Compile the code this way: gcc -Wall -pedantic -Werror -Wextra -std=gnu89 4-main.c 4-rev_array.c -o 4-rev_array
5. Always look up : A C function program that changes all lowercase letters of a string to uppercase.
   • Prototype: char *string_toupper(char *);
   • Compile the code this way: gcc -Wall -pedantic -Werror -Wextra -std=gnu89 5-main.c 5-string_toupper.c -o 5-string_toupper
6. Expect the best. Prepare for the worst. Capitalize on what comes : A C function program that capitalizes all words of a string.
   • Prototype: char *cap_string(char *);
   • Separators of words: space, tabulation, new line, ,, ;, ., !, ?, ", (, ), {, and }.
   • Compile the code this way: gcc -Wall -pedantic -Werror -Wextra -std=gnu89 6-main.c 6-cap_string.c -o 6-cap
7. Mozart composed his music not for the elite, but for everybody : A C function program that encodes a string into 1337.
   • 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.
     • 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.
   • Compile the code this way: gcc -Wall -pedantic -Werror -Wextra -std=gnu89 7-main.c 7-leet.c -o 7-1337