c++ - C++-检查单词是否为结构数据类型的回文

Question

我想知道如何检查一个单词是否是结构数据类型或对象中的回文。我想从文件中读取数据，然后需要检查所读取的单词类型是否为回文。我也需要颠倒单词的顺序，但是我做到了，所以不需要任何帮助。

这是代码:

#include <iostream>
#include <fstream>
#include <string>
#include <algorithm>

using namespace std;

struct lettersStr
{
    string name;
    string object;

};
int main(int argc, char** argv) 
{
    ifstream letter;
    letter.open("letter.txt");
    lettersStr things[200];
    int numberOfThings= 0;
    while(letter >> letter[numberOfThings].name >> letter[numberOfThings].object)
    {
        numberOfThings++;
    }

    for (int i = 0; i < numberOfThings; i++)
    {
        cout << letter[i].name << " " << letter[i].object<< endl;
    }
    string names;
    for (int i = 0; i < numberOfThings; i++)
    {
        names= things[i].name;
    }

    for (int i = numberOfThings- 1; i >= 0; i--)
    {
        cout << things[i].name << endl;
    }
    bool x = true;
    int j = names.length() - 1;
    for (int i = 0; i < j; i++,j--)
    {
        if (things[i].name.at(i) != things[i].name.at(j))
        x = false;

        if (x)
        {
            cout << "String is a palindrome ";
        }
        else
        cout << "String is not a palindrome";
    }

这是提示:

Kayak Audi
Ahmed Golf7
Ahmed
Kayak
String is not a palindrome
String is not a palindrome

我认为主要问题是:

for (int i = 0; i < j; i++,j--)
    {
        if (things[i].name.at(i) != things[i].name.at(j))
        x = false;

如您所见，它不会提供正确的方法来检查单词是否为回文。
附注:如果这是一个愚蠢的问题，对不起，我是C++编程的初学者。
干杯

Answer 1

正如评论中已经指出的那样，for (int i = 0; i < j; i++,j--)同时循环通过things及其name的字母。您还必须考虑在“皮划艇”的开头和结尾处比较大小写字母(例如“K”和“k”)的情况。您可以为此使用std::tolower。

这是一个示例(live demo):

#include <iostream>
#include <fstream>
#include <string>
#include <algorithm>
#include <vector>

using namespace std;

bool is_palindrome(std::string name)
{
    if (name.empty())
        return false;


    // As has been pointed out, you can also use std::equal.
    // However, this is closer to your original approach.
    for (unsigned int i = 0, j = name.length()-1; i < j; i++,j--)
    {
        if (std::tolower(name.at(i)) != std::tolower(name.at(j)))
            return false;
    }
    return true;
}

struct lettersStr
{
    string name;
    string object;
};

int main(int argc, char** argv) 
{

    std::vector<lettersStr> vec = {lettersStr{"Kayak","Boat"},lettersStr{"Audi","Car"}};

    for (const auto &obj : vec)
        if (is_palindrome(obj.name))
            std::cout << obj.name << " is a palindrome" << std::endl;
        else
            std::cout << obj.name << " isn't a palindrome" << std::endl;
}

它给出了输出:

Kayak is a palindrome
Audi isn't a palindrome