box-o-sand/ex15.c

#include <stdio.h>

void print_with_array_indexing(int count, char **names, int *ages)
{
    int i = 0;

    // first way using indexing
    while(i < count) {
        printf("%s has %d years alive.\n",
                names[i], ages[i]);
        i++;
    }

    printf("---\n");
}

void print_with_pointer_arithmetic(int count, char **names, int *ages)
{
    int i = 0;
    // setup the pointers to the start of the arrays
    int *cur_age = ages;
    char **cur_name = names;

    // second way using pointers
    while(i < count) {
        printf("%s is %d years old.\n",
                *(cur_name+i), *(cur_age+i));
        i++;
    }

    printf("---\n");
}

void print_with_pointers_as_arrays(int count, char **names, int *ages)
{
    int i = 0;
    int *cur_age = ages;
    char **cur_name = names;
    // third way, pointers are just arrays
    while(i < count) {
        printf("%s is %d years old again.\n",
                cur_name[i], cur_age[i]);
        i++;
    }

    printf("---\n");

}

void print_in_stupidly_complex_way(int count, char **names, int *ages)
{
    int *cur_age = ages;
    char **cur_name = names;

    // fourth way with pointers in a stupid complex way
    while((cur_age - ages) < count) {
        printf("%s lived %d years so far.\n",
                *cur_name++, *cur_age++);
    }

    printf("---\n");
}


int main(int argc, char *argv[])
{
    // create two arrays we care about
    int ages[] = {23, 43, 12, 89, 2};
    char *names[] = {
        "Alan", "Frank",
        "Mary", "John", "Lisa"
    };
    // safely get the size of ages
    int count = sizeof(ages) / sizeof(int);

    print_with_array_indexing(count, names, ages);
    print_with_pointer_arithmetic(count, names, ages);
    print_with_pointers_as_arrays(count, names, ages);
    print_in_stupidly_complex_way(count, names, ages);

    int i;
    char **arg = argv;
    for(i = 0; i < argc; i++) {
        printf("argument %d is '%s' (address = %p)\n", i, *arg, arg);
        arg++;
    }

    return 0;
}