Encoder of txt file for C

/* C Program - Encrypt Files */

#include<stdio.h>

#include<conio.h>

#include<stdlib.h>

void main()

{

system("CLS");

char fname[20], ch, choice;

FILE *fps, *fpt;

printf("Enter file name (with extension like file.txt) to encrypt : ");

gets(fname);

fps=fopen(fname, "r");

if(fps==NULL)

{

printf("Error in opening file..!!");

printf("\nPress any key to exit...");

getch();

exit(1);

}

fpt=fopen("temp.txt", "w");

if(fpt==NULL)

{

printf("Error in creating temp.txt file..!!");

fclose(fps);

printf("\nPress any key to exit...");

getch();

exit(2);

}

while(1)

{

ch=fgetc(fps);

if(ch==EOF)

{

break;

}

else

{

ch=ch+55;

fputc(ch, fpt);

}

}

fclose(fps);

fclose(fpt);

fps=fopen(fname, "w");

if(fps==NULL)

{

printf("Error in opening source file..!!");

printf("\nPress any key to exit...");

getch();

exit(3);

}

fpt=fopen("temp.txt", "r");

if(fpt==NULL)

{

printf("Error in opening temp.txt file...!!");

fclose(fps);

printf("\nPress any key to exit...");

getch();

exit(4);

}

while(1)

{

ch=fgetc(fpt);

if(ch==EOF)

{

break;

}

else

{

fputc(ch, fps);

}

}

printf("File %s encrypted successfully..!!", fname);

printf("\nPress any key to exit...");

fclose(fps);

fclose(fpt);

getch();

}