当我比较两个向量中的元素时出现错误 - 我做错了什么

任务非常简单：创建一个程序，告诉用户他或她输入的句子是否前后相同（就使用的单词而言，而不是拼写而言）。例如，"I am that am I"（请忽略这在语法上是多么荒谬）。所以我决定创建两个字符串向量 - 一个存储原始句子，另一个是颠倒的句子。每个向量的元素将是包含句子单词的字符串，例如["I", "am", "that", "am", I"]，不包括字符串中的任何空格。

我陷入了解决这个问题的初步状态 - 比较这两个向量的元素。这是我下面的代码（注意句子是第一个向量，reverseString是第二个向量，包含相反顺序的元素）：

        for (int i = 0; i < sentence.size(); i++) {
            // The below output is for debugging purposes
            cout << "The index is " << i
                 << " and the original string at this location is " << sentence[i]
                 << " and the reverse string is " << reverseString[i] << endl;
            if (sentence[i] == reverseString[i]) {
                cout << reverseString[i] << "---" << sentence[i] <<  endl;
                cout << "A match!" << endl;
            } else {
                cout << reverseString[i] << "---" << sentence[i] << endl;
                cout << "Not a match!" << endl;
            }
        }

奇怪的是，上面的代码似乎可以准确地处理索引 1 到 vector.size()-2 中的元素（请记住，c++ 向量中的索引开始和零）。但是索引 0 或 vector.size()-1 - 即每个向量的第一个和最后一个元素 - 总是产生一个"Not a match!"，无论句子是什么。两者之间的一切都被准确地比较了，但这两个位置不是。

这是一个非常奇怪的错误。也许我的错误在于创建第二个向量？这是我使用的代码：

    int t = sentence.size() - 1;
    for (int i = 0; i < sentence.size(); i++) {
        reverseString[i] = sentence[t];
        t--;
    }

改变了第一个和最后一个元素不应该成为的东西，以一种我不太清楚的方式？我的逻辑有缺陷吗？请让我知道你的想法:)

编辑：我在下面发布了我的代码的最小，完整和可验证的示例：

#include <iostream>
#include <vector>
#include <sstream>
using namespace std;
int main() {
    string input;
    cout << "Please input a sentence - no preceding or trailing spaces."
            " It will be analyzed accordingly: ";
    getline(cin, input);
    string secondString = "";
    secondString[0] = input[0];
    int i = 0; 
    for (i = 0; i <= input.length(); i++) {
        // the below strips a string of punctuation if there is any, 
        // as these characters would mess up the comparison.
        if (input[i] == ',' || input[i] == ';' || input[i] == ':' ||
            input[i] == '.' || input[i] == '?' || input[i] == '!') {
        } else {
            secondString = secondString + input[i];
        }
    }
    // now stuff the individual words in the string into a vector
    vector<string> sentence;
    // now we are going to stuff each word into a vector
    string word;
    stringstream ss(secondString);
    while (getline(ss, word, ' ')) {
        sentence.push_back(word);
    }
    // now for Task 1 - we will create a second vector that is reversed.
    // Then compare both vectors - if identical, note it. 
    vector<string> reverseString;
    reverseString = sentence; 
    int t = sentence.size() - 1;
    for (int i = 0; i < sentence.size(); i++) {
        reverseString[i] = sentence[t];
        t--;
    }
    for (int i = 0; i < sentence.size(); i++) {
        cout << "The index is " << i
             << " and the original string at this location is " << sentence[i]
             << " and the reverse string is " << reverseString[i] << endl;
        if (sentence[i] == reverseString[i]) {
            cout << reverseString[i] << "---" << sentence[i] <<  endl;
            cout << "A match!" << endl;
        } else {
            cout << reverseString[i] << "---" << sentence[i] << endl;
            cout << "Not a match!" << endl;
        }
    }
    return 0;
}