我在 c++ 中遇到 pop_back() 问题

Question

#include <iostream>
#include <string>
#include <vector>

int main() {
    // declare the variables
    std::string text;
    char vocals[] = {'a', 'i', 'u', 'e', 'o', 'A', 'I', 'U', 'E', 'O'};

    // get the input
    std::cout << "input the text: ";
    std::getline(std::cin, text);

    // declare the vector to store the vocals
    std::vector<char> v(text.length());

    // identify the vocals
    for (int i = 0; i < text.length(); i++) {
        for (int j = 0; j < 10; j++) {
            if (text[i] == vocals[j]) {
                v.push_back(text[i]);
            }
        }
    }

    // swap the vocals
    for (int i = 0; i < text.length(); i++) {
        for (int j = 0; j < 10; j++) {
            if (text[i] == vocals[j]) {
                text[i] = v.back();
                v.pop_back();
            }
        } 
    }

    // print the result
    std::cout << "the new text is: " << text << std::endl;

    return 0;
}

所以我正在尝试用 C++ 编写一个程序，可以交换句子中的声音（通过反转它）。问题是，当我输入“声乐切换测试运行”时，它输出“vucil swatch tst rn”而不是 TIA（我不是美国本土人士，也不是经验丰富的 C++ 开发人员，所以如果有任何混淆，我很抱歉带着我的问题）

我通过在最后一个 for 循环中打印 text[i] 来调试代码，所有声音都存在于向量中

Answer 1

如评论中所述，您在每个循环中都缺少

break

。添加这些中断意味着对于字符串中作为元音的每个字符，我们每次仅添加（或在第二个循环中）从向量中减去一个字符。

#include <iostream>
#include <string>
#include <vector>

int main() {
    // declare the variables
    std::string text;
    char vocals[] = {'a', 'i', 'u', 'e', 'o', 'A', 'I', 'U', 'E', 'O'};

    // get the input
    std::cout << "input the text: ";
    std::getline(std::cin, text);

    // declare the vector to store the vocals
    std::vector<char> v(text.length());

    // identify the vocals
    for (int i = 0; i < text.length(); i++) {
        for (int j = 0; j < 10; j++) {
            if (text[i] == vocals[j]) {
                v.push_back(text[i]);
                break;
            }
        }
    }

    // swap the vocals
    for (int i = 0; i < text.length(); i++) {
        for (int j = 0; j < 10; j++) {
            if (text[i] == vocals[j]) {
                text[i] = v.back();
                v.pop_back();
                break;
            }
        }
    }

    // print the result
    std::cout << "the new text is: " << text << std::endl;

    return 0;
}

$ ./a.out
input the text:  vocal switch test run
the new text is:  vucel switch tast ron