Question

程序应该提示用户输入一个5个字母的字符串。如果字符串不是5个字符，则显示错误消息。如果密码是5个字符，则使用while循环通过反转字符串中字符的顺序并从每个字符中减去15来生成密码，从而在新的字符串变量中生成密码。只能使用iostream，iomanip，cmath，字符串库。

我对这个问题唯一的问题是构造while循环，将原始字符串反转为新字符串，并从反向字符串中的每个字符中减去15以构造新密码。

#include <iostream>
#include <string>
#include <iomanip>
#include <cmath>

using namespace std;

int main()
{
    // declaring/initializing variables
    string password, newPass;
    int index;


   // greeting message
    cout << "-------------------------------" << endl
         << "     John Password Generator    " << endl
         << "-------------------------------" << endl;

    // asking user for input
    cout << "Please enter a 5 character word which will be used to generate                                                                                                              a       password: " << endl;
    getline(cin,password);

    // condition if password is less than or greather than 5 characters
    if (password.length() != 5)
    {
        cout << "Sorry, but that is not a 5 character string. Program will              terminate. \n\n"

        << "Thank you for using John Password Generator program.\n\n";
    }
    else
    {
        index = 0;
        password = string(password.rbegin(), password.rend());
        while (index < password.length())
    {

        index++;

    }


}

return 0;

}

Answer 1

您需要遍历password中的每个元素，并从中减去15：

index = 0;
password = string(password.rbegin(), password.rend());
while (index < password.length())
{
    // Minus 15 from each letter in password
    password[index] -= 15;
    // We've finished with this letter, so increment the index
    index++;
}

当然，如果您不需要使用while循环，则可以使用标准库;具体来说：std::transform转换string中的每个字母：

else
{
    // Start from the end of the string, and deduct 15 from the character and append it to the start of the string
    std::transform(password.rbegin(), password.rend(), password.begin(), [](unsigned char c){ return c - 15; });
}

随机密码生成器C ++

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