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C Exercises: Merge two files and write it in a new file

C File Handling : Exercise-12 with Solution

Write a program in C to merge two files and write it in a new file.

Assume that the content of the file test.txt and test1.txr is :                                                                       
 The content of the file test.txt is  : 
This is the file test.txt. 

 The content of the file test1.txt is  : 
This is the file test1.txt.                                                                                                    

Sample Solution:

C Code:

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

void main()
{
	FILE *fold1, *fold2, *fnew;
	char ch, fname1[20], fname2[20], fname3[30];

	printf("\n\n Merge two files and write it in a new file :\n");
	printf("-------------------------------------------------\n"); 	
	
	printf(" Input the 1st file name : ");
	scanf("%s",fname1);
	printf(" Input the 2nd file name : ");
	scanf("%s",fname2);
	printf(" Input the new file name where to merge the above two files : ");
	scanf("%s",fname3);
	fold1=fopen(fname1, "r");
	fold2=fopen(fname2, "r");
	if(fold1==NULL || fold2==NULL)
	{
//		perror("Error Message ");
		printf(" File does not exist or error in opening...!!\n");
		exit(EXIT_FAILURE);
	}
	fnew=fopen(fname3, "w");
	if(fnew==NULL)
	{
//		perror("Error Message ");
		printf(" File does not exist or error in opening...!!\n");
		exit(EXIT_FAILURE);
	}
	while((ch=fgetc(fold1))!=EOF)
	{
		fputc(ch, fnew);
	}
	while((ch=fgetc(fold2))!=EOF)
	{
		fputc(ch, fnew);
	}
	printf(" The two files merged into %s file successfully..!!\n\n", fname3);
	fclose(fold1);
	fclose(fold2);
	fclose(fnew);
}

Sample Output:

 Merge two files and write it in a new file :                                                                 
-------------------------------------------------                                                             
 Input the 1st file name : test.txt                                                                           
 Input the 2nd file name : test1.txt                                                                          
 Input the new file name where to merge the above two files : mergefiles.txt                                  
 The two files merged into mergefiles.txt file successfully..!!

Flowchart:

Flowchart: Merge two files and write it in a new file

C Programming Code Editor:

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C Programming: Tips of the Day

Difference between signed / unsigned char :

There's no dedicated "character type" in C language. char is an integer type, same (in that regard) as int, short and other integer types. char just happens to be the smallest integer type. So, just like any other integer type, it can be signed or unsigned.

It is true that (as the name suggests) char is mostly intended to be used to represent characters. But characters in C are represented by their integer "codes", so there's nothing unusual in the fact that an integer type char is used to serve that purpose.

The only general difference between char and other integer types is that plain char is not synonymous with signed char, while with other integer types the signed modifier is optional/implied.

Ref : https://bit.ly/3esiVjT