C++ for 循环字符串比较逻辑存在缺陷

Question

我的问题是:如何将 first_In_Line 和 last_In_Line 变量传递到 for 循环之外，以便我的最终语句接收变量并正确显示？

我假设学生的名字不同。

// This program allows a user to define class size, between 1 and 25
// students, and give a list of names. It does not store a list 
// of names, but does sort the names to determine alphabetically, 
// which student will be first in line, and who will be last.

#include <iostream>
#include <string>

using namespace std;

int main()
{
// Non-user defined variables
int     num_Students = 0;

string  first_In_Line = "",
        last_In_Line = "",
        previous_Name = "";

bool compare = true;

// User defined variable.
string  next_name;



// Get number of students from user between 1 and 25
cout << "Please enter the number of students in class between 1 and 25: ";
cin >> num_Students;

// Validate user input
while (num_Students < 1 || num_Students > 25)
{
    cout << "Please enter a number between 1 and 25.";
    cin >> num_Students;
}


for (int i = 1; i <= num_Students; i++)
{
    cout << "What is the name of student " << i << "? ";
    cin >> next_name;

    if (compare == true)
    {
        if (next_name < previous_Name)
        {
        first_In_Line = next_name;
        last_In_Line = previous_Name;
        }

        else if (next_name > previous_Name)
        {
        first_In_Line = previous_Name;
        last_In_Line = next_name;
        }
    }
    // Set compare to "true" to execute if statements next 
    // iteration of for-loop
    compare = true;
    previous_Name = next_name;
}

cout << first_In_Line << " is first in line." << endl;
cout << "And " << last_In_Line << " is last in line." << endl;


return 0;
}

输出是这样的，名字不正确:

请在1到25之间输入类(class)人数:3 学生 1 的名字是什么？亚当 学生 2 的名字是什么？马特 学生 3 的名字是什么？ zed 马特排在第一位。 zed 排在最后。

Answer 1

您可以取消使用 previous_name 并只使用循环遍历您的名字。您只关心排在第一位和最后一位的人。

for (int i = 1; i <= num_Students; i++)
{
    cout << "What is the name of student " << i << "? ";
    cin >> next_name;
    if (i == 1) // initialize your first entry as first and last in line (min, max)
    {
        first_In_Line = next_name;
        last_In_Line = next_name;
    }
    else // compare for last and first in line (min, max) after first iteration of for loop
    {
        if (next_name > last_In_Line)
            last_In_Line = next_name;
        else if (next_name < first_In_Line)
            first_In_Line = next_name;          
    }
}