#include <iostream> #include <string> #include <cstdlib >
using namespace std ;
void
inputError (){
c o u t <<” u s a g e : ”<< e n d l ; cout<<”./a1q3a.o {e,d}”<<endl; exit (1);

}
void normalize(string ⇤txt , int size){
char ⇤c;
for (int i=0;i<size;i++){
c=&(⇤txt )[ i ];
if ((⇤c>=’a’)&&(⇤c<=’z’)){
} ⇤ c =96;
else if((⇤c>=’A’)&&(⇤c<=’Z’)){
} ⇤ c =64;
else{⇤c=0;
} }
}
int main(int argc, const char ⇤ argv[]){
if (argc !=2){ inputError ();
}
string cmd=argv [1]; bool encode =1;
if (cmd==”e”){ }
else if (cmd==”d”){ encode =0;
}
else{inputError (); }
string input , key , output ;
11
CO 487: Assignment #1
Denis Miroshnikov 20447593

i f ( encode ){ cout<<”Plain”;
}
else{cout<<”Cipher”; }
cout<<”text :”<<endl<<endl ; getline(cin ,input); cout<<endl<<”Key:”<<endl<<endl ; getline(cin ,key);
int size=min(input.size(),key.size());
normalize(&input , size ); normalize(&key , size );
output.resize(size,’ ’); char c;
for(int j=0;j<size ; j++){
i f ( encode ){
c=(input [ j ]+key [ j ])%27;
}
e l s e {c = ( i n p u t [ j ] k e y [ j ] ) ; if (c<0){
c +=27;
} }
if (c){
output [ j]=c+64;
}e l s e {o u t p u t [ j ] = c + 3 2 ;
} }
cout<<endl ;
if (! encode){
cout<<”Plain”;
}else{cout<<”Cipher”; }

12
CO 487: Assignment #1
Denis Miroshnikov 20447593

cout<<”text :”<<endl<<endl ;
cout<<output<<endl ; }