Incomplete input from user - c++

Question

I have modified the code from my previous question, and now it looks like this:
//#include "stdafx.h"
#include <iostream>
#include <cstring>
#include <chrono>
#include <cassert>
using namespace std;
const int MAX_SIZE=10000;
const int MAX_STRINGS = 10;
char** strings=new char*[10];
int len;
char* GetLongestCommonSubstring( char* str1, char* str2 );
inline void readNumberSubstrings();
inline const char* getMaxSubstring();
void readNumberSubstrings()
{
cin >> len;
assert(len >= 1 && len <=MAX_STRINGS);
for(int i=0; i<len;i++)
strings[i]=new char[MAX_SIZE];
for(int i=0; i<len; i++)
cin >> strings[i];
}
const char* getMaxSubstring()
{
char *maxSubstring=strings[0];
auto begin = chrono::high_resolution_clock::now();
for(int i=1; i < len; i++)
maxSubstring=GetLongestCommonSubstring(maxSubstring, strings[i]);
cout << chrono::duration_cast <chrono::milliseconds> (chrono::high_resolution_clock::now()-begin).count() << endl;
return maxSubstring;
}
char* GetLongestCommonSubstring( char* string1, char* string2 )
{
if (strlen(string1)==0 || strlen(string2)==0) cerr << "error!";
int *x=new int[strlen(string2)+ 1]();
int *y= new int[strlen(string2)+ 1]();
int **previous = &x;
int **current = &y;
int max_length = 0;
int result_index = 0;
int length;
int M=strlen(string2) - 1;
for(int i = strlen(string1) - 1; i >= 0; i--)
{
for(int j = M; j >= 0; j--)
{
if(string1[i] != string2[j])
(*current)[j] = 0;
else
{
length = 1 + (*previous)[j + 1];
if (length > max_length)
{
max_length = length;
result_index = i;
}
(*current)[j] = length;
}
}
swap(previous, current);
}
delete[] x;
delete[] y;
string1[max_length+result_index]='\0';
return &(string1[result_index]);
}
int main()
{
readNumberSubstrings();
cout << getMaxSubstring() << endl;
return 0;
}
It's still solving the generalised longest common substring problem, and now it's rather fast.
But there's a catch: if a user specifies, say, 3 as a number of strings he's about to enter, and then only actually enters one string, this code waits forever.
How do I change that?

Answer 1

If you read from a file and the number of arguments isn't equal to the number of arguments provided, just print a nice, clean error message to the user.
"Expected 7 arguments, received 3:"
Print out the arguments you found so the user has an idea of what the program is looking at when it spits out the error.
As for human input, I agree with the comments. The program should wait until the user close it or enters all the needed arguments.