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C Exercises: Read an existing file

C File Handling : Exercise-2 with Solution

Write a program in C to read an existing file.

Sample Solution:

C Code:

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

void main()
{
	FILE *fptr;
	char fname[20];
	char str;
    printf("\n\n Read an existing file :\n");
	printf("------------------------------\n"); 
	printf(" Input the filename to be opened : ");
	scanf("%s",fname);
	fptr = fopen (fname, "r");  
	if (fptr == NULL)
	{
		printf(" File does not exist or cannot be opened.\n");
		exit(0);
	}
	printf("\n The content of the file %s is  :\n",fname);
	str = fgetc(fptr);
	while (str != EOF)
		{
			printf ("%c", str);
			str = fgetc(fptr);
		}
	fclose(fptr);
    printf("\n\n");
}

Sample Output:

 Read and existing file :                                                                                     
------------------------------                                                                                
 Input the filename to be opened : test.txt                                                                   
                                                                                                              
 The content of the file test.txt is  :                                                                       
This is the content of the file test.txt 

Flowchart:

Flowchart: Read an existing 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