How to remove the space character from input string?

Question

From the following code when i give input in string with space character like "John Doe" than it bypass/skip the block code(for loop). Please help me how i executed the for loop code if i entered the "John" only in cin input then it work fine and for loop code will be executed acordingly and when i use getline comand it didn't run the loop acordingly.

#include <iostream>
#include <string>
#include <fstream>

using namespace std;

int main ()
{
    string nam;
    int num;

     fstream task2;
     task2.open("task2.txt" , ios:: out);
     if(!task2)
        {
          cout<<"File not found..."<<endl;
        }   
        
    else
    { 
        cout << "Enter the number of students: " ;
        cin >> num ;
        for (int i=0 ; i <num ; i++)
        {
            cout << "Student " <<(i+1)<< endl;
            getline(cin,nam);
            task2 <<nam <<endl;
        }
        cout<<"\nData read from the file."<<endl;
        task2.close();
        task2.open("task2.txt",ios::in);
        string text;
        for(int i=0; i<num; i++)
        {
            while(getline(task2,text))
            {
                cout<<text<<endl;
                
            }
        }
        
        task2.close();
        
    }
    return 0;
}