0x0C-more_malloc_free

0x0C. C - More malloc, free

0. Trust no one

Write a function that allocates memory using malloc.

• Prototype: void *malloc_checked(unsigned int b);
• Returns a pointer to the allocated memory
• if malloc fails, the malloc_checked function should cause normal process termination with a status value of 98

solution

1. string_nconcat

Write a function that concatenates two strings.

• Prototype: char *string_nconcat(char *s1, char *s2, unsigned int n);
• The returned pointer shall point to a newly allocated space in memory, which contains s1, followed by the first n bytes of s2, and null terminated
• If the function fails, it should return NULL
• If n is greater or equal to the length of s2 then use the entire string s2
• if NULL is passed, treat it as an empty string

solution

2. _calloc

Write a function that allocates memory for an array, using malloc.

• Prototype: void *_calloc(unsigned int nmemb, unsigned int size);
• The _calloc function allocates memory for an array of nmemb elements of size bytes each and returns a pointer to the allocated memory.
• The memory is set to zero
• If nmemb or size is 0, then _calloc returns NULL
• If malloc fails, then _calloc returns NULL

FYI: The standard library provides a different function: calloc. Run man calloc to learn more.

solution

3. array_range

Write a function that creates an array of integers.

• Prototype: int *array_range(int min, int max);
• The array created should contain all the values from min (included) to max (included), ordered from min to max
• Return: the pointer to the newly created array
• If min > max, return NULL
• If malloc fails, return NULL

solution

4. _realloc

Write a function that reallocates a memory block using malloc and free

• Prototype: void *_realloc(void *ptr, unsigned int old_size, unsigned int new_size);
• where ptr is a pointer to the memory previously allocated with a call to malloc: malloc(old_size)
• old_size is the size, in bytes, of the allocated space for ptr
• and new_size is the new size, in bytes of the new memory block
• The contents will be copied to the newly allocated space, in the range from the start of ptr up to the minimum of the old and new sizes
• If new_size > old_size, the “added” memory should not be initialized
• If new_size == old_size do not do anything and return ptr
• If ptr is NULL, then the call is equivalent to malloc(new_size), for all values of old_size and new_size
• If new_size is equal to zero, and ptr is not NULL, then the call is equivalent to free(ptr). Return NULL
• Don’t forget to free ptr when it makes sense

FYI: The standard library provides a different function: realloc. Run man realloc to learn more.

solution

5. We must accept finite disappointment, but never lose infinite hope

Write a program that multiplies two positive numbers.

• Usage: mul num1 num2
• num1 and num2 will be passed in base 10
• Print the result, followed by a new line
• If the number of arguments is incorrect, print Error, followed by a new line, and exit with a status of 98
• num1 and num2 should only be composed of digits. If not, print Error, followed by a new line, and exit with a status of 98
• You are allowed to use more than 5 functions in your file

You can use bc (man bc) to check your results.