字符串操作

#include <iostream>#include <string>#include <vector>#include <algorithm>using namespace std;//判断行进方向是否为前向bool forw(string base, string fir, string sec) {    int loc1, loc2;    loc1 = base.find(fir);    if (loc1 == string::npos)        return false;    else {        loc2 = base.find(sec, loc1);        if (loc2 == string::npos)            return false;        else            return true;    }}//判断并输出结果void judge(string base, string fir, string sec) {    bool forward, backword;    forward = forw(base, fir, sec);    reverse(base.begin(), base.end());    backword = forw(base, fir, sec);    if (forward) {        if (backword)            cout << "both" << endl;        else            cout << "forward" << endl;    } else {        if (backword)            cout << "back" << endl;        else            cout << "invalid" << endl;    }}int main(){    string str;    vector<string> rec;    while (cin >> str)        rec.push_back(str);    int i = 0;    while (i < rec.size()) {        if (i % 3 == 0) {            string base = rec[i];            string fir = rec[i+1];            string sec = rec[i+2];            judge(base, fir, sec);        }        i = i+3;    }    return 0;}