'For loop' quits after 3 iterations - c++

Question

I'm trying to write code to enter 'n' Number of sentences and store it in an array. My for loop quits on the 4th iteration ? Can anyone help me?
int main(){
cout<<"Enter the number of sentences: ";
int n;
cin>>n;
cin.ignore();
char *array[50];
int br;
for (int i = 0; i<n; i++)
{
char* sentence = new char();
cout<<"Enter "<<i+1<<" sentence: ";
cin.getline(sentence,50);
br=0;
while(*sentence != '\0')
{
br++;
sentence++;
}
sentence=sentence-br;
for(int j=0; j<br; j++)
{
array[i][j] = sentence[j];
}
delete sentence;
}
for(int i=0; i<n;i++)
{
cout<<array[i]<<endl;
}
delete[] array;
return 0;
}

Answer 1

char* sentence = new char();
cout<<"Enter "<<i+1<<" sentence: ";
cin.getline(sentence,50);
This only allocates space for a single char, but you attempt to write up to 50 chars into that memory. Accessing memory that you don't own causes your program's behavior to be undefined.
for(int j=0; j<br; j++)
{
array[i][j] = sentence[j];
}
This attempts to copy the first br characters from sentence to array[i], but array is full of uninitialized pointers. Dereferencing an uninitialized pointer results in undefined behavior and then attempting to write to the memory it's "pointing" to is more undefined behavior.
delete[] array;
At the end of your program you attempt to release the memory allocated for array, but you did not allocate that memory via new. Once again, undefined behavior. array has automatic storage duration so its memory will be automatically released when it goes out of scope; you must not attempt to release it with delete.
Instead of a mix of static arrays and dynamic memory management, you should use a std::vector<std::string> instead. This will do all of the memory management for you:
#include <iostream>
#include <string>
#include <vector>
int main()
{
std::cout << "Enter the number of sentences: ";
int n;
std::cin >> n;
std::cin.ignore();
std::vector<std::string> array(n);
for (int i = 0; i < n; i++) {
std::cout << "Enter " << i + 1 << " sentence: ";
std::getline(std::cin, array[i]);
}
for (int i = 0; i < n; i++) {
std::cout << array[i] << std::endl;
}
}

Answer 2

Thank on proposal, but I'm not allowed to use string or cstring library, I've tried to code from scratch and I think I got it.
int main(){
cout<<"Enter the number of sentences: ";
int n;
cin>>n;
cin.ignore();
char** array = new char*[n];
for (int i = 0; i<n; i++)
{
cout<<"Enter "<<i+1<<" sentence: ";
array[i] = new char[50];
cin.getline(array[i],50);
}
for(int i=0; i<n;i++)
{
cout<<array[i]<<endl;
}
for(int i = 0; i<n; i++)
{
delete [] array[i];
}
delete [] array;
return 0;
}
Have I allocated and deallocated memory right?