#include <stdio.h>
#include <stdlib.h>
/**
 * Making a passing arrays in a lot of ways.  Some of which actually work.
 * Author: Gtowell
 * Created: Feb 2021
 * **/

/*
 * OK to pass the array in, but loses the length of the array
 * @param: farr -- an int array
 */
void funcc(int farr[]) {
    printf("BBB %d  %d\n", sizeof(farr), sizeof(farr[0]));
}

/**
 * The preferred way to passing an array.  In this, the link between
 * the integer passed as the size of the array, and the size of the
 * array is explicit
 * arrSize -- the number of items in the array
 * * farr the array 
 * **/
void funcc2(int arrSize, int farr[arrSize]) {
    printf("CCC %d  %d\n", sizeof(farr), sizeof(farr[0]));
}

/** DOes not work
 * Cannot return an array from a function
 * **/
/**
char[] f3(int n) {
    char arrInFunc[n];
    printf("DDD %d  %d\n", sizeof(arrInFunc), sizeof(arrInFunc));
}
**/

/**
 * This version of a function that returns an array at least compiles
 * But using the array outside of the function results in a seg fault
 * 
 * @param: n the size of the array to create
 * @return a pointer to the array
 * **/
char* f3a(int n) {
    char arrInFunc[n];
    arrInFunc[0] = 'a';
    printf("DDD %d  %d  %c\n", sizeof(arrInFunc), sizeof(arrInFunc), arrInFunc[0]);
    return (char *)arrInFunc;
}

/** THIS does not compile
 * Here we are trying to create a global array then replace/overwrite it with an array
 * created inside a function
 * 
 * @param n siz the size fo the array being created
 * **/
char globalArr[10]; // a global array to be replaced
/**
void f4(int siz) {
    char zzz[siz];
    printf("EEE %d  %d\n", sizeof(zzz), sizeof(zzz));
    globalArr = zzz;
}
**/

double  globalDArr[500];
int main(int argc, char const *argv[])
{
    int j = atoi(argv[1]);
    int arr[j];
    printf("local %d  %d  %d\n", sizeof(arr), sizeof(arr[0]), sizeof(arr)/sizeof(arr[0]));
    printf("Global %d %d  %d\n", sizeof(globalDArr), sizeof(globalDArr[0]), sizeof(globalDArr)/sizeof(globalDArr[0]));
    funcc(arr);
    funcc2(j, arr);
    char* fffa = f3a(j);
    printf("A char %c\n", fffa[0]);
    return 0;
}