Question

Selection sort on fstream data C++:

Sort the given student information data inside a text file

The format of the student data inside the text file is:

Student Number, Surname, First Name, Middle Name, Birthday, Course, Year, School Year

(The list can be updated over time so there is no limit for the size of the data)

But I need to automatically sort the given the data in ascending alphabetical order based on their surnames when displaying the list. I don't know how, please help me. Thank you :)

Answer 1

Here is the answer for your question in C++ Programming language.

What this code does?

1. Here I have given you a code that reads a file "student.txt" which contains columns as you specified.

2.Stores the surname column in a vector (as you mentioned size can be anything I used vectors)

3. Sorts the surnames column in alphabetical order and returns the vector.

4. Searches for every surname from starting in the vector with the lines in the file from starting and if founds any match displays the particular line of the file.

5. Hence the names which are in alphabetical order in the vector are used to display their lines associated with them.

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CODE:(cpp file)

//Including required header files #include<iostream> #include<fstream> #include<string> #include<vector> #include <bits/stdc++.h> //using standard namespace using namespace std; //function that compares the alphabetical order of the string bool compare(string word1,string word2) {    return word1<word2; } //method that starts sorting and takes each word in the vector as input vector<string> alphasort(vector<string> word) {    int n = word.size();    //sort method that actually does sorting    sort(word.begin(),word.end(),compare);    //returning the particular word    return word; } //main method where compilation starts int main() {    //String variable to store data of each column in text file except surname    //These are used for just storage while reading file and we no more use them again in the program    string sno , first , middle , bday , course , year ,schl_year;       //Vector to store the surnames column in the file    vector<string> surnames;    //variables to store lines of the file and to store the surnames    string line , name;    //Counters are used as eof() function reads last line twice    //To avod that counters are used counter 1 counts number of lines    //Counter 2 takes the loop to repeat through the same number of lines       int counter1 =0 , counter2 = 0;          size_t position;    //Object of ifstream    ifstream Input ;    //filename of the string    string filename = "birthday.txt";    //Opening the file    Input.open(filename.c_str());    //While lop to calculate number of lines in the file    while(getline(Input,line))    {        counter1++;    }    //After while loop as the pointer lies at end we have to close and reopen the file to start from beginning again    Input.close();    Input.open(filename.c_str());    //Second while loop that iterates through each word of the file    while(!Input.eof())    {        //Each word in every line is being stored in the respected variable name        Input >> sno >> name >> first >> middle >> bday >> course >> year >> schl_year;        //Pushig=ng only surnames to vector as they are only to be sorted        surnames.push_back(name);        //To avoid while loop to repeat last line twice        if(counter2==(counter1-1))        {            break;        }        counter2++;    }       Input.close();    Input.open(filename.c_str());    //calling alphasort function ans replacing the original vector with sorted vector    surnames = alphasort(surnames);    //Printing statements for understanding    cout << "StudentNo " << " Surname " <<" FirstName " <<" Middle " <<" BDay " <<" Course " << " Year " <<" School "<< endl;    cout << "---------------------------------------------------------------------------------------"<<endl;    //loop that iterates throuugh the size of the vector    for(int i =0;i<surnames.size();i++)    {        //At each iteration it takes current surname in vector        //while loop to iterate through the lines of file and reading every line each time in string line        while(getline(Input,line))        {            //The current surname is checked to be in currnet line of the file            position = line.find(surnames[i]);            //if yes prints the line            if(position!=string::npos)            {                cout << line << endl;            }            //if not checks the next line of the file        }        //For every while loop iteration the file needs to be closed and opened as every iteration ends at the end of the file    Input.close();    Input.open(filename.c_str());       }    return 0; }

student.txt

1 Johnes Fedrick Richard 06 CSE 2019 2013 2 Nicholas Rathon Freck 18 EEE 2018 2012 3 Coprus Jackson Rone 23 ECE 2016 2010 4 Hindle Ackson John 21 CSE 1997 1991 5 James Rathod Zafer 30 EEE 1998 1992 6 Hadrick Nelson Koman 15 CSE 2000 1994

SCREENSHOTS

Please see the screenshots for the indentations of the code.

If below is the text file (Example values taken )

Then the OUTPUT will be (sorting surnames in alphabetical order)

If you want to store the lines in the same order you can store it in another file and use them for further process.