Caesar's Gambit

#include<stdio.h>
#include<conio.h>
#include<string.h>
#include<ctype.h>
#define STRING 255
#ifndef Crypto_h
#define Crypto_h

void input(char *);
void encrypt(char []);
void decrypt(char []);
#endif

#include "Crypto.h"

void main()
{
    char message[STRING];
    int shift, choice;
    input(message);
    printf("\n\nChoose an operation:\n\n\t1.\tEncryption\n\t2.\tDecryption\n\n\tAny other\tExit.\n");
    scanf_s("%d", &choice);
    if (choice==1)
    {
        encrypt(message);
        _getch();
    }
    else if (choice == 2)
    {
        decrypt(message);
        _getch();
    }
}\\#include "Crypto.h"

void input(char *message)
{
printf_s("Please enter a message: \n");
fgets(message, 250, stdin);
for (int i=0;i<strlen(message);i++)
    {
        message[i]=toupper(message[i]);
    }
}

void encrypt(char message[])
{
    int shift;
    printf("\nPlease enter shift key\n");
    scanf_s("%d", &shift);
for (int i=0;i<strlen(message)-1;i++)
{
    if (message[i] != ' ')
    {
        message[i] = ((message[i] -'A' + shift) %26)+'A';
    }
}
puts(message);
}

void decrypt(char message[])
{
    int shift;
    printf("\nPlease enter shift key\n");
    scanf_s("%d", &shift);
    for (int i = 0; i<strlen(message) - 1; i++)
    if (message[i] != ' ')
    {
        if ((message[i] - 'A' - shift)<0)
            message[i] = (message[i] - 'A' - shift)+26+'A';
        else
        message[i] = ((message[i] - 'A' - shift) % 26) + 'A';
    }
    puts(message);
}