Sorting strings from the text file

Given a text file “file.txt” that consists of strings, the task is to sort all the strings in alphabetical order in that text file.

Approach: The idea is to use the concept of File Handling and a text file(say file.txt) that contains all the strings. Below are the steps:

• Create the file using fopen() and insert names into the file using fprintf().
• Close the file using fclose().
• Reopen the file for reading the names.
• Read or scan the names from the file using fscanf() and store it in a vector of strings.
• Sort the given string stored in the vector using the sort() function.
• Now, insert the sorted string in that file and print it.

Below is the implementation of the above approach:

C++

// C++ program to sort given array
// of string stored in a file
#include <bits/stdc++.h>
#include <cstdlib>
#include <cstring>
#include <fstream>
using namespace std;

// Driver Code
int main()
{
    int N, i, j;

    // File pointer to open file
    FILE* f;

    // fopen() for creating of a file
    f = fopen("file.txt", "w");

    // Input number of strings
    // to be inserted in file
    cin >> n;

    vector<int> name(N);

    // Insert the strings into file
    for (i = 0; i < n; i++) {

        // Insert names in file
        cin >> name[i];

        // Writing into the file
        fprintf(f, "%s", name[i]);
    }

    // Close the file
    fclose(f);

    // Reopening in read mode
    f = fopen("file.txt", "r");

    // Check does file exist or not
    if (f == NULL) {
        cout << "File doesn't exist!";
        return 0;
    }

    // Read the file until it
    // encounters end of line
    while (!feof(f)) {
        fscanf(f, "%s", name[i]);
        i++;
    }
    n = i - 1;

    // Sort the strings
    sort(name.begin(), name.end());

    // Insert the strings into file
    // after sorting
    for (i = 0; i < n; i++) {

        // Write into the file
        fprintf(f, "%s", name[i]);
    }

    // Print the sorted names
    for (i = 0; i < n; i++) {
        cout << name[i] << '\n';
    }

    return 0;
}

Python3

# Python program to sort given array of string stored in a file

# Input number of strings to be inserted in file
N = int(input("Enter the number of strings: "))

# Open file for writing
with open("file.txt", "w") as f:
    # Insert the strings into file
    for i in range(N):
        name = input("Enter the string: ")
        # Writing into the file
        f.write(name + "\n")

# Open file for reading
with open("file.txt", "r") as f:
    # Read the lines until end of file is reached
    names = [line.strip() for line in f.readlines()]

# Sort the strings
names.sort()

# Open the file for writing
with open("file.txt", "w") as f:
    # Insert the sorted strings into the file
    for name in names:
        f.write(name + "\n")

# Print the sorted names
for name in names:
    print(name)

Java

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Scanner;

public class SortStringsFromFile {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        // Input number of strings to be inserted in file
        System.out.print("Enter the number of strings: ");
        int n = scanner.nextInt();
        scanner.nextLine();

        try {
            // Open file for writing
            BufferedWriter writer = new BufferedWriter(new FileWriter("file.txt"));

            // Insert the strings into file
            for (int i = 0; i < n; i++) {
                System.out.print("Enter the string: ");
                String name = scanner.nextLine();

                // Writing into the file
                writer.write(name + "\n");
            }

            // Close the writer
            writer.close();

            // Open file for reading
            BufferedReader reader = new BufferedReader(new FileReader("file.txt"));

            // Read the lines until end of file is reached
            List<String> names = new ArrayList<String>();
            String line;
            while ((line = reader.readLine()) != null) {
                names.add(line);
            }

            // Close the reader
            reader.close();

            // Sort the strings
            Collections.sort(names);

            // Open the file for writing
            writer = new BufferedWriter(new FileWriter("file.txt"));

            // Insert the sorted strings into the file
            for (String name : names) {
                writer.write(name + "\n");
            }

            // Close the writer
            writer.close();

            // Print the sorted names
            for (String name : names) {
                System.out.println(name);
            }

        } catch (IOException e) {
            e.printStackTrace();
        }

        scanner.close();
    }
}

Input File:

Output File: