Progra to read file in C

Algorithm

Let's first see what should be the step-by-step procedure to compare two integers−

START
      
   Step 1 → Take two integer variables, say A & B
          
   Step 2 → Assign values to variables

   Step 3 → Compare variables if A is greater than B
   
   Step 4 → If true print A is greater than B
   
   Step 5 → If false print A is not greater than B

STOP

Flow Diagram

We can draw a flow diagram for this program as given below −

Pseudocode

Let's now see the pseudocode of this algorithm −

procedure compare(A, B)

   IF A is greater than B
      DISPLAY "A is greater than B"
   ELSE
      DISPLAY "A is not greater than B"
   END IF
      
end procedure

Implementation

Assuming we have file with name file_append.txt with this content −

You have opened a file using C programming language, in read-only mode.

Now, we shall see the actual implementation of the program −

#include <stdio.h>
 
int main()
{
   FILE *fp;
   char *filename = "file_read.txt";
   char ch;

   /*  open for writing */
   fp = fopen(filename, "r");

   if (fp == NULL)
   {
      printf("%s does not exists \n", filename);
      return;
   }
   else
   {
      printf("%s: opened in read mode.\n\n", filename);
   }

   while ((ch = fgetc(fp) )!= EOF)
   {
      printf ("%c", ch);
   }

   if (!fclose(fp))
      printf("\n%s: closed.\n", filename);
      
   return 0;
}

Output

Output of this program should be −

file_read.txt: opened in read mode.

You have opened a file using C programming language, in read-only mode.

file_read.txt: closed.