1: //partial_sort_copy2a.cpp
3: #include <iostream>
4: #include <vector>
5: #include <algorithm>
6: using namespace std;
8: /**
9: Tests if one integer has a smaller digit sum than another.
10: Pre:\n i1 and i2 have been initialized and i1, i2 are both > 0.
11: Post:\n Returns true if sum of the digits in i1 is < sum of digits
12: in i2, and otherwise returns false.
13: */
14: bool hasSmallerDigitSum
15: (
16: int i1, //in
17: int i2 //in
18: )
19: {
20: int digitSum1 = 0;
21: while (i1 != 0)
22: {
23: digitSum1 += i1 % 10;
24: i1 /= 10;
25: }
27: int digitSum2 = 0;
28: while (i2 != 0)
29: {
30: digitSum2 += i2 % 10;
31: i2 /= 10;
32: }
33: return digitSum1 < digitSum2;
34: }
36: int main()
37: {
38: cout << "\nThis program illustrates the use of the STL "
39: "partial_sort_copy() algorithm\n(extended version) to "
40: "order a range of values from a vector of integers of\nsize 12 "
41: "into the order determined by increasing digit sum, and copy as "
42: "many\nof them as will fit into a range within a second vector of "
43: "integers. The\ncontents of the initial vector are unchanged by "
44: "this action.";
45: cout << "\nPress Enter to continue ... "; cin.ignore(80, '\n');
47: int a1[] = {92, 21, 53, 84, 46, 13, 41, 76, 45, 61, 11, 15};
48: vector<int> v1(a1, a1+12);
49: cout << "\nHere are the initial contents of vector v1:\n";
50: for (vector<int>::size_type i=0; i<v1.size(); i++)
51: cout << v1.at(i) << " ";
52: cout << "\nPress Enter to continue ... "; cin.ignore(80, '\n');
54: int a2[] = {100, 200, 300, 400, 500};
55: vector<int> v2(a2, a2+5);
56: cout << "\nHere are the initial contents of vector v2:\n";
57: for (vector<int>::size_type i=0; i<v2.size(); i++)
58: cout << v2.at(i) << " ";
59: cout << "\nPress Enter to continue ... "; cin.ignore(80, '\n');
61: cout << "\nNow we make the following call:";
62: cout << "\np = partial_sort_copy(v1.begin(), v1.end(), "
63: "\n v2.begin(), v2.begin()+3, hasSmallerDigitSum);";
64: vector<int>::iterator p;
65: p = partial_sort_copy(v1.begin(), v1.end(),
66: v2.begin(), v2.begin()+3, hasSmallerDigitSum);
67: cout << "\nPress Enter to continue ... "; cin.ignore(80, '\n');
69: cout << "\nAfter that call, here are the contents of v1:\n";
70: for (vector<int>::size_type i=0; i<v1.size(); i++)
71: cout << v1.at(i) << " ";
72: cout << "\nPress Enter to continue ... "; cin.ignore(80, '\n');
74: cout << "\nAnd here are the contents of v2:\n";
75: for (vector<int>::size_type i=0; i<v2.size(); i++)
76: cout << v2.at(i) << " ";
77: cout << "\nPress Enter to continue ... "; cin.ignore(80, '\n');
79: cout << "\nThe iterator p returned by the algorithm points to ";
80: if (p == v2.end())
81: cout << "\nthe end of the ouput container.";
82: else
83: cout << "the value " << *p << ".";
84: cout << "\nPress Enter to continue ... "; cin.ignore(80, '\n');
86: cout << "\nNext we make the following call:";
87: cout << "\np = partial_sort_copy(v1.begin()+2, v1.end()-2, "
88: "\n v2.begin(), v2.end(), hasSmallerDigitSum);";
89: p = partial_sort_copy(v1.begin()+2, v1.end()-2,
90: v2.begin(), v2.end(), hasSmallerDigitSum);
91: cout << "\nPress Enter to continue ... "; cin.ignore(80, '\n');
93: cout << "\nAfter that call, here are the contents of v1:\n";
94: for (vector<int>::size_type i=0; i<v1.size(); i++)
95: cout << v1.at(i) << " ";
96: cout << "\nPress Enter to continue ... "; cin.ignore(80, '\n');
98: cout << "\nAnd here are the contents of v2:\n";
99: for (vector<int>::size_type i=0; i<v2.size(); i++)
100: cout << v2.at(i) << " ";
101: cout << "\nPress Enter to continue ... "; cin.ignore(80, '\n');
103: cout << "\nThe iterator p returned by the algorithm points to ";
104: if (p == v2.end())
105: cout << "\nthe end of the ouput container.";
106: else
107: cout << "the value " << *p << ".";
108: cout << "\nPress Enter to continue ... "; cin.ignore(80, '\n');
109: }