istringstream

int main()
{
    char *InputMain;
    InputMain=(char *)malloc(5+1);
    cout << "Enter the number : " <<endl;
    cin.getline ( InputMain, 5, 'n' );              // Input goes into InputMain
    cout << "The number entered is : " << InputMain <<endl;
    cin.get();
}

string str;
if (!getline(cin, str)) {
    cerr << "Something went seriously wrong...n";
}

istringstream iss(str);
int i;
iss >> i;    // Extract an integer value from the stream that wraps str

if (!iss) {
    // Extraction failed (or a more serious problem like EOF reached)
    cerr << "Enter a number dammit!n";
} else if (i < 1000 || i > 9999) {
    cerr << "Out of range!n";
} else {
    // Process i
}

int i;
cin >> i;    // Extract an integer value from cin