1: //find_first_of2a.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 "
39: "find_first_of() algorithm (extended\nversion) to find the first "
40: "occurrence of any one of a range of integer values\nin a vector "
41: "within another range of integer values, also in a vector, and "
42: "where\ncorresponding values match if and only if they have the "
43: "same digit sum.";
44: cout << "\nPress Enter to continue ... "; cin.ignore(80, '\n');
46: int a1[] = {17, 5, 13, 21, 6, 7, 8, 14, 9, 10, 11};
47: vector<int> v1(a1, a1+11);
48: cout << "\nHere are the contents of v1:\n";
49: for (vector<int>::size_type i=0; i<v1.size(); i++)
50: cout << v1.at(i) << " ";
51: cout << "\nPress Enter to continue ... "; cin.ignore(80, '\n');
53: int a2[] = {12, 41, 19};
54: vector<int> v2(a2, a2+3);
55: cout << "\nHere are the contents of v2:\n";
56: for (vector<int>::size_type i=0; i<v2.size(); i++)
57: cout << v2.at(i) << " ";
58: cout << "\nPress Enter to continue ... "; cin.ignore(80, '\n');
60: vector<int>::iterator p;
62: p = find_first_of(v1.begin(), v1.end(), v2.begin(), v2.end(),
63: digitSumsAreSame);
64: if (p != v1.end())
65: cout << "\nThe first instance of a value in v2 matching a "
66: "value in v1\nhappens at location "
67: << (int)(p-v1.begin()+1) << ".";
68: else
69: cout << "\nNo instance of a value in v2 matching a value "
70: "in v1 was found.";
71: cout << "\nPress Enter to continue ... "; cin.ignore(80, '\n');
73: p = find_first_of(p+1, v1.end(), v2.begin(), v2.end(),
74: digitSumsAreSame);
75: if (p != v1.end())
76: cout << "\nThe next instance of a value in v2 matching a "
77: "value in v1\nhappens at location "
78: << (int)(p-v1.begin()+1) << ".";
79: else
80: cout << "\nNo further instance of a value in v2 matching a "
81: "value in v1 was found.";
82: cout << "\nPress Enter to continue ... "; cin.ignore(80, '\n');
84: p = find_first_of(p+1, v1.end(), v2.begin(), v2.end(),
85: digitSumsAreSame);
86: if (p != v1.end())
87: cout << "\nThe next instance of a value in v2 matching a "
88: "value in v1\nhappens at location "
89: << (int)(p-v1.begin()+1) << ".";
90: else
91: cout << "\nNo further instance of a value in v2 matching a "
92: "value in v1 was found.";
93: cout << "\nPress Enter to continue ... "; cin.ignore(80, '\n');
95: p = find_first_of(p+1, v1.end(), v2.begin(), v2.end(),
96: digitSumsAreSame);
97: if (p != v1.end())
98: cout << "\nThe next instance of a value in v2 matching a "
99: "value in v1\nhappens at location "
100: << (int)(p-v1.begin()+1) << ".";
101: else
102: cout << "\nNo further instance of a value in v2 matching a "
103: "value in v1 was found.";
104: cout << "\nPress Enter to continue ... "; cin.ignore(80, '\n');
105: }