(2017) Lab 7, Assignment 1: "Write a program to read all txt files (that is files that ends with .txt) in the current directory and merge them all to one txt file and returns a file descriptor for the new file."

OS-Lab7-Assignment1.c

#include <stdio.h>
#include <dirent.h>
#include <string.h>

int main(void) {

	FILE *input, *output;	// Two files, input and output
	char ch;	// ch is used to assign characters from input file which will then be copied into the output file
	char *txt = ".txt"; // TXT file extension
	struct dirent *de;

	DIR *dr = opendir(".");	// Open directory for reading

	// If directory doesn't exist, quit
	if(dr == NULL) {
		printf("Can't open current directory.");
		return 0;
	}

	// Loop until all files and folders are read/accessed
	while((de = readdir(dr)) != NULL) {
		char *filename = de->d_name;	// Get the filename
		char *ext = strrchr(filename, '.');	// Get the extension

		if(!(!ext || ext == filename)){	// Compare extension
			if(strcmp(ext, txt) == 0) {	// If a text file, go on
				output = fopen("output.txt", "a+");	// Open output.txt for appending, if doesn't exist, create it.
				input = fopen(filename, "r");	// Open the input file ()'filename') for reading

				while(1) {	// Loop through the input file
					ch = fgetc(input);	// Get the current character
					if(ch == EOF) break;	// Stop if EOF is found
					putc(ch, output);	// Put current character from the input file into output.txt
				}

				fclose(input);	// Close input file
				fclose(output);	// Close output file
			}
		}
	}

	closedir(dr);	// Close directory
	printf("Succesfully copied the contents of all .txt files into output.txt.\n");
	return 0;
}