1: //inplace_merge2a.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: "inplace_merge() algorithm\n(extended version) to merge two "
40: "ordered ranges of integer values in the\nsame vector into a "
41: "single ordered range of values within that same vector.\nThe "
42: "order of values is determined by one value preceding another "
43: "if and\nonly if the first has a smaller digit sum than the "
44: "second.";
45: cout << "\nPress Enter to continue ... "; cin.ignore(80, '\n');
47: int a[] = {11, 41 , 36, 59, 98, 21, 13, 6, 52, 44, 28, 69};
48: vector<int> v(a, a+12);
50: cout << "\nHere are the contents of v:\n";
51: for (vector<int>::size_type i=0; i<v.size(); i++)
52: cout << v.at(i) << " ";
53: cout << "\nNote that the first five values form the first range, "
54: "\nand the rest of the values form the second range.";
55: cout << "\nPress Enter to continue ... "; cin.ignore(80, '\n');
57: inplace_merge(v.begin(), v.begin()+5, v.end(), hasSmallerDigitSum);
59: cout << "\nNow we perform the \"in place merge\".";
60: cout << "\nHere are the revised contents of v:\n";
61: for (vector<int>::size_type i=0; i<v.size(); i++)
62: cout << v.at(i) << " ";
63: cout << "\nPress Enter to continue ... "; cin.ignore(80, '\n');
64: }