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C program to merge two files

C program to merge two files and store their contents in another file. The files to be merged are opened in "read" mode and the file that contains contents of both the files is opened in "write" mode. For merging, we open a file and read it character by character and store the read contents in the merged file then repeat this for the second file. The files are read until their EOF (end of file) is reached.

C programming code

#include <stdio.h>
#include <stdlib.h>

int main()
{
  FILE *fs1, *fs2, *ft;

  char ch, file1[20], file2[20], file3[20];

  printf("Enter name of first file\n");
  gets(file1);

  printf("Enter name of second file\n");
  gets(file2);

  printf("Enter name of file which will store contents of the two files\n");
  gets(file3);

  fs1 = fopen(file1, "r");
  fs2 = fopen(file2, "r");

  if (fs1 == NULL || fs2 == NULL)
  {
    perror("Error ");
    printf("Press any key to exit...\n");
    exit(EXIT_FAILURE);
  }

  ft = fopen(file3, "w"); // Opening in write mode

  if (ft == NULL)
  {
    perror("Error ");
    printf("Press any key to exit...\n");
    exit(EXIT_FAILURE);
  }

  while ((ch = fgetc(fs1)) != EOF)
    fputc(ch,ft);

  while ((ch = fgetc(fs2)) != EOF)
    fputc(ch,ft);

  printf("The two files were merged into %s file successfully.\n", file3);

  fclose(fs1);
  fclose(fs2);
  fclose(ft);

  return 0;
}

Download merge files program.

Output of program:
Merge two files C program output

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