用户输入[C ++]后，txt文件中的数据将不会更改

Question

string line;
fstream search;
short loop = 0;
const int SIZE = 6;
string weight[SIZE];
int index[6] = { 1, 2, 3, 4, 5 };
int i;
int choice;
string weightChange;

search.open("name.txt"); //Opens the text file in which the user details are stored
if (search.is_open())
{
    cout << endl;
    while (getline(search, line)) { //While the program searches for the lines in the text file
        if (line.find("Current Weight(KG): ") != string::npos) { //If the string "Name" isnt the last word on the line
            weight[loop] = line; //Assings the strings read from the text file to the array called weight
            cout << index[loop] << ". " << weight[loop] << endl; //Outputs the index array which loops through the numbers in the array and outputs the weight variable which loops through the strings in the array
            loop++; //Iterates the loop 
        }
    }
        cout << "Which index would you like to change?" << endl;
        cout << "1, 2, 3, 4 or 5" << endl;
        cin >> choice;
        cout << "Weight being changed is " << weight[choice - 1] << endl;

        switch (choice) //Uses switch to allow the user to enter a number from the menu and then performs that function based on the user's input
        {
        case 1: //If the user enters choice 1, then the first weight index will be changed
            cout << "What would you like to change the user's weight to?" << endl;
            cin >> weightChange;
            weightChange = weight[1];

            search >> weight[1];

            cout << endl;
            break;
        }
}

因此，我有一个程序可以使用循环从文本文件读取用户当前的重量。然后，我必须获得用户输入他们想要更改的体重的信息。当输入他们想改变其体重的用户时，询问他们他们想改变的体重。该程序运行正常，但是当他们输入新的权重时，它不会更改txt文件中的任何内容。