Thread: What am I missing?

(Again a reminder that this language is still new to me )

I'm working on two programs, the first counts the number of vowels in a sentance inputed by the user, and uses a value returning function isVowel but I keep getting these two errors..

error C2065: 'ch' : undeclared identifier
error C2448: '<Unknown>' : function-style initializer appears to be a function definition

Am I missing something simple that I just can't see?

Code:

#include <iostream>

using namespace std;

int isVowel();

int main()
{

	char ch;

	cout << "Enter a sentence: ";
	cin.get(ch);
	return ch;
}

int isVowel(cin.get(ch))
{
	char v;
	int count;
	count = 0, v = 0;

	while (ch != '\n')
	{
		if(ch == 'A' || ch == 'a' || ch =='E' || ch == 'e'
			|| ch == 'I' || ch == 'i' || ch == 'O' || ch == 'o'
			|| ch == 'U' || ch == 'u')
			count++;
		v++;
	}

	cout << "There are" << v << "in this sentance" << endl;
	return 0;
}

My second is supposed to determine an estimated population after a number of years from the current population, birth rate, death rate, and number of years inputed by the user using a growthRate funtion(birth, death), and an estimatedPopulation funtion(current pop, growth rate, and n) I managed to get past the 24 errors (lol I said I was new to this) but I still have 4 warnings about variables being used without being initialized, how do I correct this?

Code:

#include<iostream>
using namespace std;

int growthRate (int, int);
int estimatedPopulation (int, double, int);

int main()
{
	int pop;
	int birth;
	int death;
	int num;
	
	cout << "Enter current population: ";
	cin >> pop;
	
	cout << "Enter birth rate: ";
	cin >> birth;

	cout << "Enter death rate: ";
	cin >> death;
	
	cout << "Enter the number of years for the projected population: ";
	cin >> num;


	return 0;
}

int growthRate(int birth, int death)
{
	int pop;
	int popgrowth;

	if (pop > 2)
		cout << "Population must be greater than 2 ";
	

	if (birth > 0)
		cout << "Birth rate must be a positive number";


	if (death > 0)
		cout << "Death rate must be a positive number";

	popgrowth = birth - death;
	
	cout << "Growth rate = " << popgrowth << "%" << endl;
	return popgrowth;
}

int estimatedPopulation (int currentpop, int popgrowth, int num)
{
	int pop;
	int estpop;
	int birth;
	int death;

	currentpop = pop + (birth * pop / 100) - (death * pop / 100);

	estpop = currentpop * num;

	cout << "Projected population after" << num << "years = " << estpop << endl;
	return estpop;
}

Code:

#include <iostream>

using namespace std;

void isVowel();

int main()
{

    char ch;

    cout << "Enter a sentence: ";
    cin.get(ch);  // Does this function work OK with getting chars?
    isVowel(ch);
    //return ch;

    return 0; // Always return 0 in main
}

void isVowel(char ch)
{
    char v;
    int count;
    count = 0, v = 0;

    while (ch != '\n')
    {
        if(ch == 'A' || ch == 'a' || ch =='E' || ch == 'e'
            || ch == 'I' || ch == 'i' || ch == 'O' || ch == 'o'
            || ch == 'U' || ch == 'u')
            count++;
        v++;
    }

    cout << "There are" << v << "in this sentance" << endl;
    //return 0;
}

Here are some helper comments on the population C++ source:

Code:

#include<iostream>
using namespace std;

int growthRate (int, int);
int estimatedPopulation (int, double, int);

int main ()
{
  int pop;
  int birth;
  int death;
  int num;

  cout << "Enter current population: ";
  cin >> pop;

  cout << "Enter birth rate: ";
  cin >> birth;

  cout << "Enter death rate: ";
  cin >> death;

  cout << "Enter the number of years for the projected population: ";
  cin >> num;


  return 0;
}

int growthRate (int birth, int death)
{
  int pop;
  int popgrowth;

  // pop is uninitialized
  /*if (pop < 2) // Changed the sign > to <
  {
     cout << "Population must be greater than 2 ";
     return -1;  // Added this to exit function
  } */

  if (birth < 0)    // Changed the sign > to <
  {
    cout << "Birth rate must be a positive number";
    return -1;      // Added this to exit function
  }

  if (death < 0)    // Changed the sign > to <
  {
    cout << "Death rate must be a positive number";
    return -1;      // Added this to exit function
  }


  popgrowth = birth - death;

  cout << "Growth rate = " << popgrowth << "%" << endl;
  return popgrowth;
}

int estimatedPopulation (int currentpop, int popgrowth, int num)
{
  int pop;
  int estpop;
  int birth;
  int death;

  // pop is uninitialized
  //currentpop = pop + (birth * pop / 100) - (death * pop / 100);

  // currentpop is uninitialized
  // estpop = currentpop * num;

  // estpop is uninitialized
  // cout << "Projected population after" << num << "years = " << estpop << endl;
  // return estpop;

  // We have to return something now that I've commented everything lol
  return 0;
}