ranFun.cpp

#include <iostream> // includes and statements section
#include <string> // strings
#include <cstdlib> // c standard library
#include <ctime> // time

using std::cin; // user input
using std::cout; // machine output
using std::endl; // for line breaks
using std::strtol; // convert string to int 
using std::string; //string
using std::getline; //getline

/**
 * Return whether the given `inputMaximum` contains a whole number (an integer >= 0).
 *
 * @return [true] if all characters are in '0' to '9'
 * @return [false] otherwise
 * @see http://stackoverflow.com/a/1885793/470451
 **/
bool wholeNumber(const string& input){
	bool notAnInteger = false;

	for (int i = 0; i < input.length(); i++) {
		  if (!(input.at(i) >= '0' && input.at(i) <= '9')) {
		    cout << "Your number is not a whole number!" << endl;
		    notAnInteger = true;
		    
		    break;
		  }
	}
	
	return notAnInteger;
}

int main () {
	string inputMinimum;
	string inputMaximum;
	int minimum;
	int maximum;
	
	// use a do while loop because you want it to run at least once.
    do {
        // have to ensure 0 or while loop may fail to continue on flip due to random
        // initialization
        minimum = 0;
        maximum = 0;
        
		cout << "RANDOM NUMBER GENERATOR!" << endl;
		cout << "Please enter a minimum whole number for our range: " << endl;
		getline(cin, inputMinimum);
		
		bool notAnInteger = false;
			
		notAnInteger = wholeNumber(inputMinimum);
		
		if (notAnInteger) {
		 continue;
		}
		
		// convert string to integer now that we know nothing will get cut off
		minimum = atoi(inputMinimum.c_str());
		
		cout << "Now please enter a maximum whole number for our range: " <<endl;
		getline(cin, inputMaximum);
		
		notAnInteger = wholeNumber(inputMaximum);
		
		}
		
		if (notAnInteger) {
		 continue;
		}
		
		// convert string to integer now that we know nothing will get cut off
		maximum = atoi(inputMaximum.c_str());
		
		if (minimum >= maximum)
		{
			cout << "I'm sorry, your minimum is greater than or equal to your maximum. Please try again!" << endl;
		}
	}
	while (minimum >= maximum);
	
	// seed the random number generator
	srand(time(NULL)); // Used 'NULL' instead of 0, defined as null pointer in http://www.cplusplus.com/reference/ctime/time/?kw=time
		
	int range = maximum - minimum + 1;
	int randomInRange = minimum + rand() % range;
	cout << "Your random number is: " << randomInRange << endl ;

	return 0;
}