A question about dice probability and 2D array - c++

Question

Find out the probability of different total values when several unbiased dices were thrown at the same time. The program makes use of various techniques including basic I/O, arithmetic, conditional control structures, loops and arrays.
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I am using the 2d array to finish the work. However, it was not okay to go on as it outputted the problem of "out of the scope".
#include <iostream>
using namespace std;
int main()
{
//Initialise the variables
int number;
cout << "Input the number of dice(s): ";
cin >> number;
//Initialise 2d array and set number as the row
int face[20][20];
for (int i = 0; i < number; i++) {
cin >> face[i + 1][20];
}
//Initialise 2d array and set input value as the column
int value;
for (int i = 0; i < number; i++) {
//Consider the output statement of the number of faces for dice
switch (number + 1) {
case 1:
cout << "Input the number of the faces for the " << number + 1 << "st" << " dice: ";
break;
case 2:
cout << "Input the number of the faces for the " << number + 1 << "nd" << " dice: ";
break;
case 3:
cout << "Input the number of the faces for the " << number + 1 << "rd" << " dice: ";
break;
default:
cout << "Input the number of the faces for the " << number + 1 << "th" << " dice: ";
}
cin >> face[i][value];
}
//calculate the sum of the dice
int sum = 0;
for (int i = 0; i < number; i++) {
sum = sum + face[i][value];
}
//initialise the base value (max probability) of the dice
int base;
for (int i = 0; i < number; i++) {
base = base * face[i][value];
}
//Output statement
if (number < 10) {
for (int i = number; i < sum; i++) {
cout << "Probability of " << i << " = " << probability(i, base, face);
}
}
else {
for (int i = number; i < 10; i++) {
cout << "Probability of " << i << " = " << probability(i, base, face);
}
for (int i = 10; i < sum; i++) {
cout << "Probability of " << i << " = " << probability(i, base, face);
}
}
return 0;
}
//Calculating the probability
int probability(int number, int base, int face[20][20])
{
int probability = 0;
int rollresult = face[0][0];
while (rollresult == number) {
for (int i = 0; i < number; i++) {
for (int j = 0; j; j++) {
rollresult = face[i][j] + rollresult;
}
}
probability++;
}
return probability;
}
error messages:
In function 'int main()':
51:69: error: 'probability' was not declared in this scope
56:70: error: 'probability' was not declared in this scope
59:70: error: 'probability' was not declared in this scope

Answer 1

The problem is that you are trying to call the probability() function before you have declared it! You can keep the actual definition after main but you will then need to put a 'forward' declaration of it earlier on. Try inserting a declaration, immediately before 'main`, thus:
int probability(int number, int base, int face[20][20]);
int main() {
...