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  1. //Devin Scheu                                  CS1A                                    Chapter 6, P. 173, #15
  2. //
  3. /**************************************************************
  4. *
  5. * CALCULATE POPULATION GROWTH OVER YEARS
  6. * ____________________________________________________________
  7. * This program determines the population size over a specified
  8. * number of years based on starting size, birth rate, and death rate.
  9. * ____________________________________________________________
  10. * INPUT
  11. * startingPopulation : The initial population size
  12. * birthRate : The annual birth rate percentage
  13. * deathRate : The annual death rate percentage
  14. * numYears : The number of years to calculate
  15. *
  16. * OUTPUT
  17. * populationTable : The population size for each year
  18. *
  19. **************************************************************/
  20.  
  21. #include <iostream>
  22. #include <iomanip>
  23.  
  24. using namespace std;
  25.  
  26. // Function to calculate population for a year
  27. double calculatePopulation(double previousPopulation, double birthRate, double deathRate) {
  28.     double births = previousPopulation * (birthRate / 100);
  29.     double deaths = previousPopulation * (deathRate / 100);
  30.     return previousPopulation + births - deaths;
  31. }
  32.  
  33. int main () {
  34.  
  35. 	//Variable Declarations
  36. 	double startingPopulation;    //INPUT      - The initial population size
  37. 	double birthRate;            //INPUT      - The annual birth rate percentage
  38. 	double deathRate;            //INPUT      - The annual death rate percentage
  39. 	int numYears;                //INPUT      - The number of years to calculate
  40. 	double currentPopulation;    //OUTPUT     - The population size for each year
  41. 	string populationTable;      //OUTPUT     - The population size for each year
  42.  
  43. 	//Prompt for Input and Echo
  44. 	cout << "Enter the starting population size: ";
  45. 	cin >> startingPopulation;
  46. 	while (startingPopulation < 2) {
  47. 		cout << "\nError: Please enter a number greater than or equal to 2: ";
  48. 		cin >> startingPopulation;
  49. 	}
  50. 	cout << startingPopulation << endl;
  51.  
  52. 	cout << "Enter the annual birth rate (%): ";
  53. 	cin >> birthRate;
  54. 	while (birthRate < 0) {
  55. 		cout << "\nError: Please enter a non-negative birth rate: ";
  56. 		cin >> birthRate;
  57. 	}
  58. 	cout << birthRate << "%" << endl;
  59.  
  60. 	cout << "Enter the annual death rate (%): ";
  61. 	cin >> deathRate;
  62. 	while (deathRate < 0) {
  63. 		cout << "\nError: Please enter a non-negative death rate: ";
  64. 		cin >> deathRate;
  65. 	}
  66. 	cout << deathRate << "%" << endl;
  67.  
  68. 	cout << "Enter the number of years: ";
  69. 	cin >> numYears;
  70. 	while (numYears < 1) {
  71. 		cout << "\nError: Please enter a number greater than or equal to 1: ";
  72. 		cin >> numYears;
  73. 	}
  74. 	cout << numYears << endl;
  75.  
  76. 	//Separator and Output Section
  77. 	cout << "-------------------------------------------------------" << endl;
  78. 	cout << "OUTPUT:" << endl;
  79.  
  80. 	//Display Header
  81. 	cout << fixed << setprecision(0);
  82. 	cout << left << setw(15) << "Year" << right << setw(20) << "Population" << endl;
  83. 	cout << "-----------------------------------------------" << endl;
  84.  
  85. 	//Calculate and Display Population for Each Year
  86. 	currentPopulation = startingPopulation;
  87. 	for (int year = 0; year <= numYears; year++) {
  88. 		if (year == 0) {
  89. 			cout << left << setw(15) << "Starting" << right << setw(20) << static_cast<long long>(currentPopulation) << endl;
  90. 		} else {
  91. 			currentPopulation = calculatePopulation(currentPopulation, birthRate, deathRate);
  92. 			cout << left << setw(15) << year << right << setw(20) << static_cast<long long>(currentPopulation) << endl;
  93. 		}
  94. 	}
  95.  
  96. } //end of main()
Success #stdin #stdout 0s 5308KB
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stdin
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100000
3
5
5
stdout
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Enter the starting population size: 100000
Enter the annual birth rate (%): 3%
Enter the annual death rate (%): 5%
Enter the number of years: 5
-------------------------------------------------------
OUTPUT:
Year                     Population
-----------------------------------------------
Starting                     100000
1                             98000
2                             96040
3                             94119
4                             92236
5                             90392
https://ideone.com/0MX79d
language:
C++ (gcc 8.3)
created:
7 hours ago
visibility:
public

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