C++ - invalid conversion from 'int' to 'int**' - c++

Question

I have this following code:
#include<iostream>
using namespace std;
void insert(int *a[], const int location, const int numofelements, const int value) {
int n, b[10];
a = *b;
for (int n = numofelements; n > location; n--) {
a[n-1] = a[n];
}
b[location] = value;
*b = a;
}
int main() {
int test[10] = [1,2,3,4,5];
insert(test, 2, 5, 7);
for (int i = 0; i < 6; i++) {
cout << "test[" << i << "] = " << test[i];
}
return 0;
}
And the compiler says:
[Error] invalid conversion from 'int' to 'int**' [-fpermissive]
[Error] invalid conversion from 'int**' to 'int' [-fpermissive]
What does it mean? Thanks

Answer 1

Errors like this mean you are mixing integers and pointers to integers.
There is several cases in your code where that happens.
Lets look at pointers in this example
//defining
int a; //int, a is an integer holding the value
int *b; //*int, a pointer to an integer
int c[10]; //*int, arrays are to pointers to the first element with some different rules
int **d; //**int, this is a pointer to a pointer
int *d[10];//**int, this is a pointer to a an array, and arrays similar to pointers
//using pointers
a = *b; //* before a pointer returns its value
a = b[0]; //resolving the position of an array also returns its value
b = &a; //& before a value returns the address
Lets take a look at your code
#include<iostream>
using namespace std;
void insert(int *a[], const int location, const int numofelements, const int value) {
int n, b[10];
a = *b; //a is **int. *b means the first element so *b is an int.
for (int n = numofelements; n > location; n--) {
a[n-1] = a[n];
}
b[location] = value;
*b = a; //a is **int. *b means the first element so *b is an int.
}
int main() {
int test[10] = [1,2,3,4,5];
insert(test, 2, 5, 7); //test is a *int, the function expects a **int
for (int i = 0; i < 6; i++) {
cout << "test[" << i << "] = " << test[i];
}
return 0;
}
Here is a tutorial on using pointers