1: //equal2a.cpp
3: #include <iostream>
4: #include <vector>
5: #include <algorithm>
6: using namespace std;
8: /**
9: Tests if two positive integers have the same digit sum.
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 digitSumsAreSame
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 equal() "
39: "algorithm (extended\nversion) to test whether the integers in a "
40: "range of integers in one vector\nmatch the integers in another "
41: "range in a different vector, in the sense of\nvalues in "
42: "corresponding positions having the same digit sum.";
43: cout << "\nPress Enter to continue ... "; cin.ignore(80, '\n');
45: int a1[] = {21, 13, 5};
46: vector<int> v1(a1, a1+3);
47: cout << "\nHere are the contents of v1:\n";
48: for (vector<int>::size_type i=0; i<v1.size(); i++)
49: cout << v1.at(i) << " ";
50: cout << "\nPress Enter to continue ... "; cin.ignore(80, '\n');
52: int a2[] = {21, 22, 23, 30, 31, 32};
53: vector<int> v2(a2, a2+6);
54: cout << "\nHere are the contents of v2:\n";
55: for (vector<int>::size_type i=0; i<v2.size(); i++)
56: cout << v2.at(i) << " ";
57: cout << "\nPress Enter to continue ... "; cin.ignore(80, '\n');
59: cout << "\nFirst we compare the sequence in v1 with the sequence "
60: "starting at the\nbeginning of v2, and ask whether they match.";
61: if (equal(v1.begin(), v1.end(), v2.begin(), digitSumsAreSame))
62: cout << "\nYes, they match.";
63: else
64: cout << "\nNo, they don't match.";
65: cout << "\nPress Enter to continue ... "; cin.ignore(80, '\n');
67: cout << "\nThen we compare the sequence starting at the beginning "
68: "of v1 with the\nsequence starting at the second value of v2 "
69: "and ask whether they match.";
70: if (equal(v1.begin(), v1.end(), v2.begin()+1, digitSumsAreSame))
71: cout << "\nYes, they match.";
72: else
73: cout << "\nNo, they don't match.";
74: cout << "\nPress Enter to continue ... "; cin.ignore(80, '\n');
76: cout << "\nFinally, we compare the sequence starting at the "
77: "beginning of v1 with the\nsequence starting at the second "
78: "value of v2 and ask whether they match.";
79: if (equal(v1.begin(), v1.end(), v2.begin()+3, digitSumsAreSame))
80: cout << "\nYes, they match.";
81: else
82: cout << "\nNo, they don't match.";
83: cout << "\nPress Enter to continue ... "; cin.ignore(80, '\n');
84: }