有一些解答存在缺陷

练习 5.21 代码有缺陷。比如使用 hello Man big Man error 这样的字符串，它认为 Man 连续出现了两次，实际上 Man 和 Man 之间有个 big。

#include <iostream>
#include <string>
using namespace std;

int main(int argc, char const *argv[])
{
    string currString, preString;
    bool bl = true;
    cout << "Enter a set of strings: " << endl;
    while (cin >> currString) {
        if (!isupper(currString[0]))
            continue;
        if (currString == preString) {
            bl = false;
            cout << "The repeat string is: " << currString << endl;
            break;
        }
        preString = currString;
    }
    if (bl)
        cout << "There is no repeat string." << endl;
    return 0;
}

为了配合书中刚讲的内容而使用 continue，结果导致代码不严密，像上面那个字符串就是例子。改成下面这个形式应该就可以了：

#include <iostream>
#include <string>
using namespace std;

int main(int argc, char const *argv[])
{
    string currString, preString;
    bool bl = true;
    cout << "Enter a set of strings: " << endl;
    while (cin >> currString) {
        if (currString == preString && isupper(currString[0])) {
            bl = false;
            cout << "The repeat string is: " << currString << endl;
            break;
        }
        preString = currString;
    }
    if (bl)
        cout << "There is no repeat string." << endl;
    return 0;
}