Double pointer 2d array c++

/* QUESTION:
Double pointers use write a program to store alphabets to a table (length of table during program execution) using

double pointer. Pass the table as arguments to a function. Print the vowels to the screen.

Hint: Your will use new operator to allocate memory.

Note: You have to release the memory using delete operator before the end of program.
*/

 // CODE :

 #include<iostream>
using namespace std;
void find_vowels(char **ptr,int a,int b);
int main(){
int a,b;
cout<<"Enter the no of rows your table for storing alphabets ";
cin>>a;
 char **ptr = new char *[a];
 cout<<"Enter the no of coloumns";
cin>>b;
 for (int i=0;i<a;i++){
  ptr[i] = new char[b];
 }
 cout<<"\n\nEnter the characters\n";
 for (int j=0;j<a;j++){
  for(int k=0;k<b;k++){
      cin>>ptr[j][k];
  }
 }
 cout<<"\n The vowels out of table are\n\n";
 find_vowels(ptr,a,b);
for(int p=0; p< a;p++)
delete [] ptr[p];
delete [] ptr;
 return 0;
}
void find_vowels(char **ptr,int a,int b){
 for (int l=0;l<a;l++){
  for(int m=0;m<b;m++){
   if (ptr[l][m] == 'a'||ptr[l][m] =='e'||ptr[l][m] =='i'||ptr[l][m] =='o'|| ptr[l][m] =='u'){
    cout<<ptr[l][m]<<endl;
   }


  }

 }
}