Question

Write a C program using system call I/O to

a) open an existing text file passed to your program as a command line argument, then

b) display the content of the file,

c) ask the user what information he/she wants to append

d) receive the info from the user via keyboard

e) append the info received in

d) to the end of the file

f) display the updated content of the file

Answer 1

Code Screenshot :

Executable Code:

#include <stdio.h>
//Main Program
int main(int argc, char* argv[]){
   //Opening the file
   FILE* f = fopen(argv[1], "a+");
   //Printing the existing content in the file
   printf("Existing content: \n");
   char ch;
   //Reading till the end of file
   while((ch = fgetc(f)) != EOF) printf("%c", ch);
   //Prompting the user for input
   printf("Enter info to be appended: \n");
   char content[100];
   //Reading the input
   fgets(content, 100, stdin);
   //Writing to file
   fprintf(f,"%s", content);
   fseek(f,0,SEEK_SET);
   //Printing contents of the file
   printf("File after appending: \n");
   while((ch = fgetc(f)) != EOF) printf("%c", ch);
   fclose(f);
}

Sample Output :

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