adding char[] to dynamic array and deallocate from a function - c++

Question

I need some help since I'm new to c++, I have a homework question where we should read a name to a char[] and then place that input inside a dynamic array, sort the dynamic array, and then terminate the allocated memory. We have to work with a half-done written program and I don't think I'm getting the input incorrectly in the dynamic array and I have a problem with deallocating memory could someone help with some tips maybe? My contribution to the code is highlighted in ** ** thanks!
const int BUFLEN = 100; // Max length of reading buffer
void sort(char* friendList[], int n); // n is the number of elements
void print(char* friendList[], int n); // n is the number of elements
void terminate(char* friendList[], int n); // n is the number of elements
const int AMOUNT = 5;
int main()
{
char* friends[AMOUNT]; // Dynamic array with AMOUNT pcs of string pointers
char buff[BUFLEN] = { "" }; // Creates a string buffer (null terminated)
int count = 0;
while (count < AMOUNT) // enter AMOUNT number of friends
{
cout << "Name a friend: ";
cin.getline(buff, BUFLEN); // Temporary reading into string buffer
friends[count] = **new char[AMOUNT];** //. . . WRITE CODE allocating memory to the string
// WRITE CODE that adds loaded name to current location in the dynamic array
**strcpy(friends[count], buff);**
++count;
}
sort(friends, count); // Sorts the ‘count’ strings
print(friends, count); // Prints the ‘count’ first names
terminate(friends, count);// Releases all allocated memory space
return 0;
}
void sort(char* friendList[], int n)
{
// WRITE FUNCTION that sorts the strings in the friendList in alphabetical order!
**int result;
for (int i = 0; i < n - 1; i++)
{
for (int j = 0; j < n - 1 - i; j++)
{
result = strcmp(friendList[j+1], friendList[j]);
if (result < 0)
swap(friendList[j+1], friendList[j]);
}
}**
}
void print(char* friendList[], int n)
{
// WRITE FUNCTION that prints ‘n’ names from the friendList on screen!
**for (int i = 0; i < n; i++)
{
cout << friendList[i] << " " << i << endl;
}**
}
void terminate(char* friendList[], int n)
{
// WRITE FUNCTION that releases all dynamically allocated memory!
**for (int i = 0; i < n; i++)
{
delete friendList[i];
}
delete [] friendList;
cout << "deleted! ";**
}

Answer 1

I see a few problems with this code:
In main():
not validating that cin.getline() is successful before using the contents of buff.
AMOUNT is the wrong size to use when allocating a new char[] to store in friends[]. The correct size should be either strlen(buff)+1 or cin.gcount().
In terminate() (not to be confused with std::terminate()):
delete[]'ing the input array itself, which was not allocated with new[] to begin with and thus must not be delete[]'ed.

Answer 2

Instead of this statement
friends[count] = new char[AMOUNT];
you need to write
friends[count] = new char[strlen( buff ) + 1];
Pay attention to that the array friends itself is not allocated dynamically. But each its element points to a dynamically allocated array. So the function terminate can look like
void terminate(char* friendList[], int n)
{
// WRITE FUNCTION that releases all dynamically allocated memory!
for (int i = 0; i < n; i++)
{
delete [] friendList[i];
friendList[i] = nullptr;
}
cout << "deleted! ";
}