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  1. //Zachary Abdollahi				CS1A					  Chapter 6, P. 373, #15
  2. //
  3. /*******************************************************************************
  4.  * 
  5.  * COMPUTE POPULATION GROWTH
  6.  * 
  7.  * This program calculates and displays the projected size of a population over
  8.  * a specified number of years based on annual birth and death rates.
  9.  * 
  10.  * Computation is based on the formula:
  11.  * N = P + (B * P) - (D * P)
  12.  * 
  13.  * INPUT
  14.  *	startingPop  : Starting size of the population
  15.  *  birthRate    : Annual birth rate (as a percentage)
  16.  *  deathRate    : Annual death rate (as a percentage)
  17.  *  years        : Number of years to project
  18.  * 
  19.  * OUTPUT
  20.  *	newPop       : Calculated population size for each year
  21.  * 
  22.  ******************************************************************************/
  23.  
  24.  #include <iostream>
  25.  #include <iomanip>
  26.  using namespace std;
  27.  
  28.  // Function Prototypes
  29.  int calculatePopulation(int pop, double birthRate, double deathRate);
  30.  
  31.  int main()
  32.  {
  33.  	int population;		// Starting/current population size
  34.  	double birthRate;	// Annual birth rate
  35.  	double deathRate;	// Annual death rate
  36.  	int years;			// Number of years to display
  37.  
  38.  	// Get the starting population (must be at least 2)
  39.  	cout << "Enter the starting population size: ";
  40.  	cin >> population;
  41.  	while (population < 2)
  42.  	{
  43.  		cout << "Population must be at least 2. Enter starting population: ";
  44.  		cin >> population;
  45.  	}
  46.  
  47.  	// Get annual birth rate (cannot be negative)
  48.  	cout << "Enter the annual birth rate (e.g., 0.05 for 5%): ";
  49.  	cin >> birthRate;
  50.  	while (birthRate < 0)
  51.  	{
  52.  		cout << "Birth rate cannot be negative. Enter birth rate: ";
  53.  		cin >> birthRate;
  54.  	}
  55.  
  56.  	// Get annual death rate (cannot be negative)
  57.  	cout << "Enter annual death rate (e.g., 0.02 for 2%): ";
  58.  	cin >> deathRate;
  59.  	while (deathRate < 0)
  60.  	{
  61.  		cout << "Death rate cannot be negative. Enter death rate: ";
  62.  		cin >> deathRate;
  63.  	}
  64.  
  65.  	// Get number of years (must be at least 1)
  66.  	cout << "Enter the number of years to project: ";
  67.  	cin >> years;
  68.  	while (years < 1)
  69.  	{
  70.  		cout << "Years must be at least 1. Enter number of years: ";
  71.  		cin >> years;
  72.  	}
  73.  
  74.  	// Display table header
  75.  	cout << "\n----------------------------------------" << endl;
  76.  	cout << "Year\t\tProjected Population" << endl;
  77.  	cout << "----------------------------------------" << endl;
  78.  
  79.  	// Calculate and display populatiob for each year
  80.  	for (int year = 1; year <= years; year++)
  81.  	{
  82.  		population = calculatePopulation(population, birthRate, deathRate);
  83.  		cout << year << "\t\t" << population << endl;
  84.  	}
  85.  
  86.  	return 0;
  87.  }
  88.  
  89.  /******************************************************************************
  90.   * 						calculatePopulation								   *
  91.   * Accepts the previous population, birt rate, and death rate as arguments,   *
  92.   * calculates the new population size using N = P + BP -DP, and returns the   *
  93.   * result as an integer.													   *
  94.   *****************************************************************************/
  95.   int calculatePopulation(int pop, double birthRate, double deathRate)
  96.   {
  97.   	return pop + (birthRate * pop) - (deathRate * pop);
  98.   }
Success #stdin #stdout 0s 5328KB
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stdin
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100000
0.05
0.02
5
stdout
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Enter the starting population size: Enter the annual birth rate (e.g., 0.05 for 5%): Enter annual death rate (e.g., 0.02 for 2%): Enter the number of years to project: 
----------------------------------------
Year		Projected Population
----------------------------------------
1		103000
2		106090
3		109272
4		112550
5		115926
https://ideone.com/yzdibr
language:
C++ (gcc 8.3)
created:
1 day ago
visibility:
public

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