How compiler works with arrays? - c

Question

I am writing a code to find the factor of the user given number. And then I want to store all the factors in an array. I created two functions, factors and insert_element. factors will find the factor and insert_element will store the factor in array as loop continues. When i call insert_element function form factors it shows me an error like warning: passing argument 1 of ‘insert_element’ from incompatible pointer type [-Wincompatible-pointer-types]. I have no idea what this means and how it occurred as I am new at C language. I would like to know how a bit about how compiler works with array along with how this error occurred
I am extremely SORRY if the question title and the question body seems to be misleading..
Here's my code below:
// PROGRAME TO FIND FACTORS OF GIVEN NUMBER"
#include <stdio.h>
void insert_element(int *factor_array[], int *base_divisor, int *index_of_array_elements)
//I heve used * because i want to ruturn more then one thing
{
*factor_array[*index_of_array_elements] = *base_divisor;
*index_of_array_elements++;
}
void factors(int number)
// I dont know if I want to return something or not so i kept it of type void
{
int base_divisor = 2, factor_array[50], index_of_array_elements = 0;
// base_divisor starts dividing given number from 2
while (number != 1)
{
if (number % base_divisor==0) //If remainder is zero then only devide number by base_divisor
{
number = number / base_divisor;
}
else //If remainder is not zero then base_divisor will be increase by 1.
{
base_divisor++;
}
// calling the function to insert element in array
insert_element(&factor_array[50], &base_divisor, &index_of_array_elements);
}
//i dont know why i did this but error is not caused by this.
printf("%ls", factor_array);
}
int main()
{
int number;
printf("\nPROGRAME TO FIND FACTORS OF GIVEN NUMBER\n\n");
printf("Enter the number to find factor: ");
scanf("%d", &number);
factors(number);
}

Answer 1

As written, the code in your post is outputting values that are not always factors. Only during the final iteration of the loop is the value for factor_array (if stored correctly) a quotient and a factor, which of course should also mean it is prime.
The following example, for simplification removes one function, and modifies the prototype of the remaining function to take a struct array argument. The struct itself contains values for quotient, factor, base. The code is also commented to explain some of the modification. In particular I hope this will help you to understand how to pass an array as a function argument, and how to use a loop to output the values in an array.
typedef struct {
long long factor;
long long quotient;
long long base;
}elements_s;
elements_s factor_array[50] = {{0}};
//REMOVED as all the work done here is moved to it's calling function
// void insert_element(size_t arr_size int *factor_array[], int *base_divisor, int *index_of_array_elements)
////I heve used * because i want to ruturn more then one thing
//{
//
// *factor_array[*index_of_array_elements] = *base_divisor;
// *index_of_array_elements++;
//
//
//}
void factors(long long number, size_t size, elements_s arr[size])//changed to pass container for results.
// I dont know if I want to return something or not so i kept it of type void
{
long long base_divisor = 2, /**factor_array[50],*/ index_of_array_elements = 0;//factor_array replaced by struct array
arr[index_of_array_elements].factor = 1;//fill array here, no need to send via function
arr[index_of_array_elements].quotient = number;
arr[index_of_array_elements].base = base_divisor;
int i=0;
// base_divisor starts dividing given number from 2
while (number != 1 && base_divisor < LLONG_MAX )
{
if (number % base_divisor==0) //If remainder is zero then only devide number by base_divisor
{
index_of_array_elements++;//index array index
number = number / base_divisor;
arr[index_of_array_elements].factor = base_divisor;//fill array here, no need to send via function
arr[index_of_array_elements].quotient = number;//fill array here, no need to send via function
arr[index_of_array_elements].base = base_divisor;//fill array here, no need to send via function
}
else //If remainder is not zero then base_divisor will be increase by 1.
{
base_divisor++;
}
//REMOVED for simplification of example (Not needed)
// calling the function to insert element in array
//insert_element(&factor_array[50], &base_divisor, &index_of_array_elements);
//insert_element(&factor_array, &base_divisor, &index_of_array_elements);
}
//i dont know why i did this but error is not caused by this.
for(i = 0;i < index_of_array_elements-1; i++)//putting into loop so all populated element of array are output
{
printf("quotient:%lld\nfactor:%lld\n", factor_array[i].quotient,factor_array[i].factor);//using %d for int
}
printf("base divisor:%lld\nfactor and quotient:%lld\nfactor:%lld\n", factor_array[i].base, factor_array[i].quotient,factor_array[i].factor);//using %d for int
}
int main(void)//this is a minumum signature for main. Anything less is not portable.
{
long long number = 0; //allows larger values up to 9223372036854775807 (LLONG_MAX)
//int factor_array[50] = {0};
size_t size = sizeof factor_array/sizeof *factor_array;
printf("\nPROGRAME TO FIND [prime] FACTORS OF GIVEN NUMBER\n\n");
printf("Enter the number to find factor...\n");
scanf("%lld", &number);//format specifier changed to accomodate larger type
factors(number, size, factor_array);//factor_array contains all the results here,
// so prinf could be used here if index were
// also passed as argument
return 0;//int main(void) requires this statement
}
Example run for value: 1234567890: (multiply all factors to test for input)