Getting random numbers to stay the same from function to function - c++

Question

Relatively new to C++ and this has been bugging me for a while. I'm trying to write a program that will do different things depending on what random number is generated.
To explain what I'm trying to do simply, lets pretend I'm creating a list of athletes and start by randomly generating their heights within a certain range. Easy to do no problem. Say then I want to generate their weight, based on their height. This is where things get messy. For some reason I can't figure out, the program is randomly generating the weight based on a different height than the one it returns in the first place. I just don't get it.
Anyway, here is a piece of (very simplified) sample code that hopefully shows what I'm trying to do. I'm sure I'm missing something obvious but I just can't seem to figure it out.
#include "stdafx.h"
#include <stdio.h>
#include <iostream>
#include <time.h>
using namespace std;
int random(int min, int max, int base)
{
int random = (rand() % (max - min) + base);
return random;
}
int height()
{
int height = random(1, 24, 60);
return height;
}
int weight()
{
int weight = height() * 2.77;
return weight;
}
void main()
{
srand ((unsigned int)time(0));
int n = 1;
while (n <= 10)
{
cout << height() << " and " << weight() << endl;
++n;
}
return;
}

Answer 1

weight is calling height again, and it will obviously be generating a different number (that's the whole point of an RNG :) ).
To obtain the effect you want you could:
change weight to accept the the height as a parameter; then, in the main, at each iteration save the value returned by height in a temporary variable and pass it to height to obtain the corresponding height;
int weight(int height)
{
return height*2.77;
}
// ... inside the main ...
while (n <= 10)
{
int curHeight=height();
cout << curHeight << " and " << weight(curHeight) << endl;
++n;
}
move height and weight to a class, which will store height as a private field, adding a nextPerson member that will update the internal field to a new random value.
class RandomPersonGenerator
{
int curHeight;
public:
RandomPersonGenerator()
{
nextPerson();
}
int height() { return curHeight; }
int weight() { return height()*2.77; }
void nextPerson()
{
curHeight=random(1, 24, 60);
}
};
// ... inside the main ...
RandomPersonGenerator rpg;
while (n <= 10)
{
rpg.nextPerson();
cout << rpg.height() << " and " << rpg.weight() << endl;
++n;
}
(by the way, it's int main, not void main, and a for cycle is more appropriate than while in this situation)

Answer 2

It's quite easy. You call height() in your weight() function. That means you're getting a new random value for the height. What you have to do is to modify your weight() so that it can pass through a height parameter and calculate the weight based on it (and not on a new random value).
Your new height() function would look as follow:
int weight(int height)
{
int weight = height * 2.77;
return weight;
}
In your main():
while (n <= 10)
{
int h = height();
int w = weight(h);
cout << h << " and " << w << endl;
++n;
}