CaesarCrypt

#include <fstream>
#include <cstring>
using namespace std;

int main()
{
    char s[256],opt[8];
    int n;
    ifstream f("caesar.in");
    f.get(s,256);
    f.get();
    f>>n;
    f.get();
    f.get(opt,8);
    f.close();
    int L=strlen(s);
    if(strcmp(opt,"encrypt")==0)
        for(int i=0;i<L;++i)
        {
            if((s[i]>='A'&&s[i]<='Z')||(s[i]>='a'&&s[i]<='z'))
            {
                if(s[i]>'Z') ///s[i] e minuscula
                    if(s[i]-'a'+n>25)
                        s[i]='a'+(s[i]-'a'+n)%26;
                    else
                        s[i]=(s[i]-'a'+n)+'a';
                else /// s[i] e majuscula
                    if(s[i]-'A'+n>25)
                        s[i]='A'+(s[i]-'A'+n)%26;
                    else
                        s[i]=(s[i]-'A'+n)+'A';
            }
        }
    else
        for(int i=0;i<L;++i)
        {
            if((s[i]>='A'&&s[i]<='Z')||(s[i]>='a'&&s[i]<='z'))
            {
                if(s[i]>'Z') ///s[i] e minuscula
                    if(s[i]-'a'-n<0)
                        s[i]='a'+26-(-(s[i]-'a'-n)%26);
                    else
                        s[i]=(s[i]-'a'-n)+'a';
                else /// s[i] e majuscula
                    if(s[i]-'A'-n<0)
                        s[i]='A'+26-(-(s[i]-'A'-n)%26);
                    else
                        s[i]=(s[i]-'A'-n)+'A';
            }
        }
    ofstream g("dbftbs.out");
    g<<s<<'\n';
    g.close();
    return 0;
}