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  1. #include <iostream>
  2. #include <cmath>
  3. using namespace std;
  4.  
  5. class EOF_Exception : public exception {};
  6.  
  7. // Input an integer in a loop until given a valid number
  8. int inputInteger(const char* message){
  9. 	int n;
  10.  
  11. 	while(1){
  12. 		cout << message;
  13. 		cin >> n;
  14.  
  15. 		// Throw exception if end-of-file (EOF) is given on input
  16. 		if(cin.eof()) throw EOF_Exception();
  17.  
  18. 		// Break this loop only the input is valid, otherwise print and error and redo.
  19. 		if(!cin.fail()) break;
  20. 		cout << "ERROR: Invalid integer input" << endl; 
  21. 	}
  22.  
  23. 	return n;
  24. }
  25.  
  26. // A struct to hold the bounds and length() for the number of ..numbers.. in the range.
  27. typedef struct {
  28. 	int lower;
  29. 	int upper;
  30.  
  31. 	int length(){ return upper - lower + 1; }
  32. } Range;
  33.  
  34. // Inputs the bounds in a loop until valid bounds are given (lower <= upper)
  35. Range inputRange(){
  36. 	Range range;
  37.  
  38. 	while(1){
  39. 		range.lower = inputInteger("Enter lower limit: ");
  40. 		range.upper = inputInteger("Enter upper limit: ");
  41.  
  42. 		// Break this loop only the range is valid, otherwise print and error and redo.
  43. 		if(range.lower <= range.upper) break;
  44. 		cout << "ERROR:" "lower bound (" << range.lower << ") is greater than " \
  45. 				 "upper bound (" << range.upper << ")" << endl;
  46. 	}
  47.  
  48. 	return range;
  49. }
  50.  
  51. // Iterates the given range and performs the summation + count of even numbers
  52. // NOTE: Calculating the even/odd numbers can be done directly from the bounds without a loop
  53. // which is probably better. I didn't bother, but you can lol =)
  54. // NOTE: Printing is also done here for simplicity, but it is preferable to avoid mixing
  55. // "user interface" operations (like printing to console) with "business logic" (our algorithm).
  56. void iterate_range(Range range){
  57. 	int sum = 0, num_odds = 0;
  58.  
  59. 	// NOTE: I thought of making a custom iterator to make this more elegant, but for
  60. 	// simplicity I've left it the way it is
  61. 	for(int n = range.lower; n <= range.upper; ++n){
  62. 		sum += n;
  63. 		if(sum % 2) ++num_odds;
  64.  
  65. 		// Printing the sum, spaces are added only in between (it annoys me otherwise)
  66. 		if(n != range.lower) cout << " ";
  67. 		cout << sum;
  68. 	}
  69. 	// Print a new line character at the end of the lsit of sums printed in the loop.
  70. 	cout << endl;
  71.  
  72. 	cout << "Even nubmers: "  << range.length() - num_odds << endl;
  73. 	cout << "Odd numbers: " << num_odds << endl;
  74. }
  75.  
  76. // The entry point to the program.
  77. int main(int argc, char **argv){
  78. 	try{
  79. 		Range range = inputRange();
  80. 		iterate_range(range);
  81. 	}
  82. 	catch(EOF_Exception& e){
  83. 		return 1;
  84. 	}
  85.  
  86. 	return 0;
  87. }
  88.  
Success #stdin #stdout 0s 3420KB
comments (?)
stdin 
3
15
stdout 
Enter lower limit: Enter upper limit: 3 7 12 18 25 33 42 52 63 75 88 102 117
Even nubmers: 6
Odd numbers: 7
https://ideone.com/7mtw3I
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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