C++ Input from user before Output to file - c++

Question

I have this code that should get minimal value and maximal value from user before writing random numbers to a file but it writes to the file and skips the waiting for user input. How to wait and get the user input before writing to file and use the input from the user to write to the file.
Solution: It works except that I have run the following command: g++ randomNumbers.cpp and expected the program to run right after but I forgot to run it manually by running the output file.
#include <iostream>
#include <fstream>
#include <string>
const bool CREATE_FILE = true;
void getMinMax(int&,int&);
void writeFile(std::ofstream&, int&, int&);
int main(){
if (CREATE_FILE){
int min;
int max;
std::ofstream outfile;
getMinMax(min, max);
writeFile(outfile, min, max);
}
}
void getMinMax(int& min,int& max){
std::cout << "Enter min: ";
std::cin >> min;
std::cout << "Enter max: ";
std::cin >> max;
}
void writeFile(std::ofstream& file, int& min, int& max){
file.open("numbers.txt", std::fstream::out);
for (int i = 1; i <= 10; i++){
file << min + (rand() % (int)(max - min + 1));
}
file.close();
}

Answer 1

I don't see any problem with this program. It does what is expected, using Visual Studio 2015 Express. The only bug I see is this:
file << min + (rand() % (int)(max - min + 1));
This appends numbers to the file one after the other, without any separating whitespace. The result for me was the text file containing:
208131917161201920
I'd replace that line with:
file << min + (rand() % (max - min + 1)) << ' ';
By itself, I cannot see how this code does not work on your machine. Try using a different compiler or state the explicit results of the program on your end (e.g. does "numbers.txt" ever get created, and if so, what is inside it if anything?). If this is merely a segment of a larger file, then std::cin is likely reading leftover garbage from the input buffer. Try adding this in the body of getMinMax before requesting user input:
std::cin.ignore(MAX_INT);
std::cin.clear();
And not that this is relevant, but it's not necessary to manually close a file at the end of a function in C++. When std::fstream goes out of scope, its destructor will the close the file automagically. Furthermore, pass ints by value instead of by reference if your function doesn't intend to change them. From the style of your code, I'm guessing you're used to programming in C and are trying to make a switch; it helps to start writing idiomatic C++ code early
EDIT: Try rewriting the getMinMax method as:
#include <sstream>
void getMinMax(int& Min, int& Max)
{
using namespace std;
cin.ignore(MAX_INT);
cin.clear();
string temp;
cout << "Enter min: "
getline(cin, temp);
stringstream(temp) >> Min;
cout << "Enter max: "
getline(cin, temp);
stringstream(temp) >> Max;
//printf("(Min, Max) = (%i, %i)\n", Min, Max); //For debugging
}
This is a verbose but somewhat safer version of what you posted. If this doesn't work, then I don't know what to tell you. If it does work, then my guess is that the input stream was polluted somehow.

Answer 2

I suggest the following:
Fix the missing include: i.e. add include <stdlib.h> to your file.
Open a terminal and navigate to the directory where your randomNrs.cpp file (or whatever you named it) lives.
Compile it: You said you are using g++, so you just run g++ randomNrs.cpp -o randomNrs in that directory - the -o flag will let you name your binary something else than the default a.out. In this example it would be named randomNrs.
Run it: Then run your executable from within that directory by typing ./randomNrs
These where the steps I went through in order to run your program. I'm on RHEL but it should be the same on OS X I think.