heap-memory.c

#include <stdio.h>
#include <stdlib.h>

#define ALPHABET_LEN 26

char *string_malloc(size_t size);
char *string_calloc(size_t size);
char *string_realloc(char *original, size_t new_len);
void fill_lowercase(char *str, size_t len);


int main()
{
    char *str = string_calloc(ALPHABET_LEN + 1);
    fill_lowercase(str, ALPHABET_LEN + 1);
    printf("%s\n", str);
    printf("%p\n", str);
    str = string_realloc(str, (2 * ALPHABET_LEN) + 1);
    fill_lowercase(&str[ALPHABET_LEN], ALPHABET_LEN + 1);
    printf("%s\n", str);
    printf("%p\n", str);
    free(str);
    str = NULL;
}

char *string_realloc(char *original, size_t new_len)
{
    original = realloc(original, new_len);
    if (original == NULL) {
        fprintf(stderr, "Out of Memory");
        exit(EXIT_FAILURE);
    }
    return original;
}

char *string_calloc(size_t size)
{
    char *str = calloc(size, sizeof(char));
    if (str == NULL) {
        fprintf(stderr, "Out of Memory");
        exit(EXIT_FAILURE);
    }
    return str;
}


char *string_malloc(size_t size)
{
    char *str = malloc(size);
    if (str == NULL){
        fprintf(stderr, "Out of memory");
        exit(EXIT_FAILURE);
    }
    for (size_t i = 0; i < size; ++i) {
        str[i] = '\0';
    }
    return str;
}

void fill_lowercase(char *str, size_t len)
{
    if (len > 26) {
        len = 27;
    }

    for (size_t i = 0; i < len - 1; ++i) {
        str[i] = 'a' + i;
    }
    str[len - 1] = '\0';
}