01  #include<stdio.h>
02  
03  int main()
04  {
05   char c;
06  
07   FILE *fp;   // file pointer
08   
09   fp=fopen("c:\my_text.txt","w");  //open a file for writing (file_path,mode)
10  
11   while((c=getchar())!=EOF)     //EOF denotes end of file (ctrl + Z) from keyboard
12   {
13    putc(c,fp);  //writing a single character to a file
14   }
15   fclose(fp);  //closing a file
16  
17   printf("nReading data from file :n");
18  
19   fp=fopen("c:\my_text.txt","r");  //open a file for reading (file_path,mode)
20  
21   while((c=getc(fp))!=EOF)    //EOF denotes end of file
22   {
23    putchar(c);        //print character to screen
24   }
25   fclose(fp);          // closing the file
26   
27   return 0;
28   }

 OUTPUT :
 
 Hey,
 This is a file demo.^Z
 
 Reading data from file :
 Hey,
 This is a file demo.