Compiler Error C2440 in C - c

Question

I'm finishing a program that I found in my C book but I ran into some issues.
I'm just about done but I keep getting this error
Error 1 error C2440: 'function' : cannot convert from 'double [15]' to '
Why am i getting this compiler error?
void arrayRead(double, int*);
void arrayList(double, int*);
void arraySum(double, int*, int*);
#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<ctype.h>
int main()
{
int num, sum = 0;
double array[15];
printf("How many doubles (numbers) would you like in the array (20 max)?\n");
scanf("%d", &num);
printf("Thank you! Now give me %d different doubles (numbers) please!\n", num);
arrayRead(array, &num);
printf("Here are all of your integers again!\n");
arrayList(array, &num);
arraySum(array, &num, &sum);
printf("The sum of these numbers = %d\n", sum);
return 0;
}
void arrayRead(double array[], int* num)
{
for (int i = 0; i < *num; i++)
{
scanf("%lf", &array);
}
}
void arrayList(double array[], int*num)
{
for (int i = 0; i < *num; i++)
{
printf("%.2f\n", array);
}
}
void arraySum(double array[], int*num, int* sum)
{
for (int i = 0; i < *num; i++)
{
*sum = array + *sum;
}
}

Answer 1

best to place prototypes after any #include statements,
just in case the prototype uses something defined in the header file
The size of the array must be a positive number,
so use '%u' to input a positive numbe
and define the max variable as unsigned
The parameters to functions and the parameters passed when calling those functions need to have matching types (or the function type be a 'promotion' of the passed type.
since the array is doubles, all the references should also be double, like the sum variable.
appropriate horizontal white space makes the code much easier to read
do not #include header files those contents are not being used.
#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>
//#include <ctype.h>
// prototypes
void arrayRead( double*, unsigned );
void arrayList( double*, unsigned );
void arraySum ( double*, unsigned, double* );
int main( void )
{
unsigned num;
double sum = 0.0;
printf( "How many doubles (numbers) would you like in the array (20 max)?\n" );
if( 1 != scanf( "%u", &num ) )
{
perror( "scanf for size of array failed" );
exit( EXIT_FAILURE );
}
// implied else, scanf successful
// need to add check that user entered value is in range 1...20
double array[ num ];
printf( "Thank you! Now give me %u different doubles (numbers) please!\n", num );
arrayRead( array, num );
printf( "Here are all of your integers again!\n" );
arrayList( array, num );
arraySum( array, num, &sum );
printf("The sum of these numbers = %lf\n", sum);
return 0;
} // end function: main
void arrayRead( double array[], unsigned num )
{
for ( unsigned i = 0; i < num; i++ )
{
scanf("%lf", &array[i]);
}
} // end function: arrayRead
void arrayList( double array[], unsigned num )
{
for ( unsigned i = 0; i < num; i++ )
{
printf("%.2f\n", array[i]);
}
} // end function: arrayList
void arraySum( double array[], unsigned num, double* sum )
{
for ( unsigned i = 0; i < num; i++ )
{
*sum = array[i] + *sum;
}
} // end function: arraySum
Here is the output from a simple run of the answer code:
How many doubles (numbers) would you like in the array (20 max)?
5
Thank you! Now give me 5 different doubles (numbers) please!
1 1 1 1 1
Here are all of your integers again!
1.00
1.00
1.00
1.00
1.00
The sum of these numbers = 5.000000

Answer 2

The functions you have declared have different signatures than the functions you have defined.
Be careful in the declaration you use double instead of double *. It is not the same.
When you call the arrayRead function and company, the compiler sees only the declared functions as the defined functions are after the calls. So the parameters doesn't match.
By the way, in the defined functions you forgot to write the index. You are using the pointer and this can't work. You need to write array[i] inside each loop.