Two files DATA1 and DATA2 contain sorted lists of integers. Write a program to produce a third file DATA which holds a single sorted, merged list of these two lists. Use command line arguments to specify the file names.

Introduction

Code

Practical-31.c

#include <stdio.h>
#include <stdlib.h> // includes the library that provides functions to send and receive commands from operating system

//Main function starts here
int main( int arg[BC[BCA, Cyber Security]yber Security]har *argv[]) {
  FILE *fp1; //creates a file pointer
  FILE *fp2; //creates a file pointer
  FILE *fp3; //creates a file pointer

  int n1, n2; //variable to store integer numbers

  fp1=fopen(argv[1],"r"); //command to open DATA1 text file in read mode
  fp2=fopen(argv[2],"r"); //command to open DATA2 text file in read mode
  fp3=fopen("DATA","w"); //command to open a new file DATA in write mode

  // loop to read numbers from text files and compare them
  while(fscanf(fp1,"%d",&n1) != EOF && fscanf(fp2,"%d",&n2) != EOF) {
    if (n1 <= n2) {
      fprintf(fp3,"%d \n",n1); //write the smaller number into DATA
      fscanf(fp1,"%d",&n1);    //update n1 so that we can compare the next number
    }
    else {
      fprintf(fp3,"%d \n",n2); //write the smaller number into DATA
      fscanf(fp2,"%d",&n2);    //update n2 so that we can compare the next numbers
    }
  }

 // to write the leftover numbers from either file
  while(fscanf(fp1,"%d",&n1) != EOF)
    fprintf(fp3,"%d \n",n1);
  while(fscanf(fp2,"%d",&n2) != EOF)
    fprintf(fp3,"%d \n",n2);

  fclose(fp1); // close the DATA1 text file
  fclose(fp2); // close the DATA2 text file

  return 0;

}

Output

Enter the name of the first file: DATA1
Enter the name of the second file: DATA2
The merged file is: DATA