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#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <assert.h>
#include <string.h>
// okay to copy/adapt
// though know this is pretty straight forward stuff (that is, stuff you might find in the documentation)

void _print_string_comparison(char* str1, char* str2) {
    if (str1 == str2) {
        printf("Strings addresses are equal\n");
    } else {
        printf("Strings addresses are not equal\n");
    }
    // strcmp is not just doing string equality, its also for string sorting
    // as a result, we have to check == 0 to check string equality
    if (strcmp(str1, str2) == 0) {
        printf("Strings contents are equal\n");
    } else {
        printf("Strings contents are not equal\n");
    }
}


int main(int argc, char* argv[]) {
    char s_on_stack[] = "abc";
    s_on_stack[0] = 'd';
    printf("s_on_stack = '%s'\n", s_on_stack);
    printf("size of s_on_stack = %ld\n", sizeof(s_on_stack));
    printf("size of s_on_stack[0] = %ld\n", sizeof(s_on_stack[0]));

    // illegal assignment: cannot modify an array variable with a strin constant
//  s_on_stack = "def";
    /*
strings.c: In function 'main':
strings.c:12:20: error: assignment to expression with array type
   12 |         s_on_stack = "def";
      |                    ^
          */
    printf("s_on_stack = '%s'\n", s_on_stack);
    printf("size of s_on_stack = %ld\n", sizeof(s_on_stack));
    printf("size of s_on_stack[0] = %ld\n", sizeof(s_on_stack[0]));

    char* s_on_data = "abc";
    // illegal operation: causes a seg fault at runtime
    // no modifying string constants from the data segment
    //s_on_data[0] = 'd';
    printf("s_on_data = '%s'\n", s_on_data);
    printf("size of s_on_data = %ld\n", sizeof(s_on_data));
    printf("size of s_on_data[0] = %ld\n", sizeof(s_on_data[0]));
    s_on_data = "def";
    printf("s_on_data = '%s'\n", s_on_data);
    printf("size of s_on_data = %ld\n", sizeof(s_on_data));
    printf("size of s_on_data[0] = %ld\n", sizeof(s_on_data[0]));


    // compiler error: cannot initialize a string on the stack using string another variable
//  char s_on_stack2[] = s_on_data; 
/*
strings.c: In function 'main':
strings.c:22:30: error: invalid initializer
   22 |         char s_on_stack2[] = s_on_data;
      |                              ^~~~~~~~~
*/
    char* s_addr = s_on_data;
    printf("s_addr = '%s'\n", s_addr);
    s_addr = s_on_stack;
    s_addr[0] = 'a'; // can modify because it *currently* refers to the address of a stack allocated string
    printf("s_addr = '%s'\n", s_addr);


    _print_string_comparison(s_on_data, s_addr);
    /* cannot == compare to a string constant
strings.c: In function 'main':
strings.c:62:20: error: comparison with string literal results in unspecified behavior [-Werror=address]
   62 |         if (s_addr == "def") {
      |                    ^~
cc1: all warnings being treated as errors
     */
    /*
    if (s_addr == "def") {
        printf("String is equal to string constant\n");
    }
    */
    char* str1 = "def";
    char* str2 = "def";
    _print_string_comparison(str1, str2);
    char str_on_stack_def[] = "def";
    printf("Two strings with the same data, one on data, one on stack\n");
    _print_string_comparison(str1, str_on_stack_def);

    return EXIT_SUCCESS;
}
/* vim: set tabstop=4 shiftwidth=4 fileencoding=utf-8 noexpandtab: */

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