C program to merge two files

Write a C program to merge two files.

  #include <stdio.h>
  #include <string.h>
  #define MAX 256

  int main() {
        int ch;
        FILE *fp1, *fp2, *fp3;
        char fname1[MAX], fname2[MAX], temp[] = {"temp.txt"};

        /* get the first input file name from the user */
        printf("Enter your first file name:");
        fgets(fname1, MAX, stdin);
        fname1[strlen(fname1) - 1] = '\0';

        /* get the second input file name from the user */
        printf("Enter your second file name:");
        fgets(fname2, MAX, stdin);
        fname2[strlen(fname2) - 1] = '\0';

        /* open first input file in read mode */
        fp1 = fopen(fname1, "r");

        /* error handling */
        if (!fp1) {
                printf("Unable to open input file %s\n", fname1);
                return 0;
        }

        /* open second input file in read mode */
        fp2 = fopen(fname2, "r");

        /* error handling */
        if (!fp2) {
                printf("Unable to open input file %s\n", fname2);
                fclose(fp1);
                return 0;
        }

        /*

         * open a temporary file to write the contents

         * of first and second input files

         */

        fp3 = fopen(temp, "w");

        /* error handling */

        if (!fp3) {

                printf("Unable to open temporary file to write!!\n");

                return 0;

        }

        /* copy the contents of first file to temporary file */

        while ((ch = fgetc(fp1)) != EOF) {

                fputc(ch, fp3);

        }

        /* copy the contents of second file to temporary file */

        while ((ch = fgetc(fp2)) != EOF) {

                fputc(ch, fp3);

        }

        /* close all opened files */

        fclose(fp1);

        fclose(fp2);

        fclose(fp3);

        /* remove the input files */

        remove(fname1);

        remove(fname2);

        /* rename the temporary file to first file name */

        rename(temp, fname1);

        return 0;

  }

  Output:

  jp@jp-VirtualBox:~/$ cat first.txt 
  When I Asked God for Strength
  He Gave Me Difficult Situations to Face
  
  When I Asked God for Brain & Brown
  He Gave Me Puzzles in Life to Solve

  When I Asked God for Happiness
  He Showed Me Some Unhappy People

  When I Asked God for Wealth
  He Showed Me How to Work Hard

  jp@jp-VirtualBox:~/$ cat second.txt 
  When I Asked God for Favors
  He Showed Me Opportunities to Work Hard

  When I Asked God for Peace
  He Showed Me How to Help Others

  God Gave Me Nothing I Wanted
  He Gave Me Everything I Needed.
                ― Swami Vivekananda

  jp@jp-VirtualBox:~/$ ./a.out
  Enter your first file name: first.txt
  Enter your second file name: second.txt

  jp@jp-VirtualBox:~/$ cat first.txt 
  When I Asked God for Strength
  He Gave Me Difficult Situations to Face

  When I Asked God for Brain & Brown
  He Gave Me Puzzles in Life to Solve

  When I Asked God for Happiness
  He Showed Me Some Unhappy People

  When I Asked God for Wealth
  He Showed Me How to Work Hard

  When I Asked God for Favors
  He Showed Me Opportunities to Work Hard

  When I Asked God for Peace
  He Showed Me How to Help Others

  God Gave Me Nothing I Wanted
  He Gave Me Everything I Needed.
                  ― Swami Vivekananda

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