Encrypt file

#include<stdio.h>
#include<conio.h>

int main(){
  char fname[20], ch;
  FILE *fps, *fpt;
  printf("Enter Filename: ");
  gets(fname);
  fps = fopen(fname, "r");
  if(fps == NULL)
    return 0;
  fpt = fopen("temp.txt", "w");
  if(fpt == NULL)
    return 0;
  ch = fgetc(fps);
  while(ch != EOF){
    ch = ch+100;
    fputc(ch, fpt);
    ch = fgetc(fps);
  }
  fclose(fps);
  fclose(fpt);
  fps = fopen(fname, "w");
  if(fps == NULL)
    return 0;
  fpt = fopen("temp.txt", "r");
  if(fpt == NULL)
    return 0;
  ch = fgetc(fpt);
  while(ch != EOF){
    ch = fputc(ch, fps);
    ch = fgetc(fpt);
  }
  fclose(fps);
  fclose(fpt);
  printf("\nFile %s Encrypted Successfully!", fname);
  getch();
  return 0;
}