cout won't print string

[Protoman]

I'm trying to print a string, and cout isn't printing it; here's my
code:

#include <iostream>
#include <cstdlib>
#include <string>
#include <cctype>
using namespace std;

namespace
{
void convert(string& String)
{
for(int i=0;i<String.length();i++)
String[i]=(toupper(String[i]));
return;
}

string encrypt(const string& cleartext,const string& key)
{
string encrypted;
for(int i=0;i<cleartext.length();i++)
encrypted[i]+=(cleartext[i]+key[i%key.length()])%26;
return encrypted;
}

string decrypt(const string& ciphertext,const string& key)
{
string decrypted;
for(int i=0;i<ciphertext.length();i++)
decrypted[i]+=(ciphertext[i]-key[i%key.length()])%26;
return decrypted;
}
}

int main()
{
string cleartext;
string key;
cout << "Enter cleartext: ";
getline(cin,cleartext,'\n');
cout << "Enter key: ";
getline(cin,key,'\n');
convert(cleartext);
convert(key);
string ciphertext=encrypt(cleartext,key);
cout << "Ciphertext: " << ciphertext << endl;
cout << "Cleartext: " << decrypt(ciphertext,key) << endl;
system("PAUSE");
return 0;
}

Any ideas as to what might be wrong? Thanks!!!

[Alf P. Steinbach]

* Protoman:

I'm trying to print a string, and cout isn't printing it; here's my
code:

#include <iostream>
#include <cstdlib>
#include <string>
#include <cctype>
Add

#include <stdexcept>

using namespace std;

namespace
{
void convert(string& String)
{
for(int i=0;i<String.length();i++)
String[i]=(toupper(String[i]));
return;
}

string encrypt(const string& cleartext,const string& key)
{
string encrypted;
for(int i=0;i<cleartext.length();i++)
encrypted[i]+=(cleartext[i]+key[i%key.length()])%26;
If you consistently replace "[i]" with ".at(i)" you'll find some errors.

return encrypted;
}

string decrypt(const string& ciphertext,const string& key)
{
string decrypted;
for(int i=0;i<ciphertext.length();i++)
decrypted[i]+=(ciphertext[i]-key[i%key.length()])%26;
return decrypted;
}
}

int main()
{
string cleartext;
string key;
cout << "Enter cleartext: ";
getline(cin,cleartext,'\n');
cout << "Enter key: ";
getline(cin,key,'\n');
convert(cleartext);
convert(key);
string ciphertext=encrypt(cleartext,key);
cout << "Ciphertext: " << ciphertext << endl;
cout << "Cleartext: " << decrypt(ciphertext,key) << endl;
system("PAUSE");
return 0;
}

Any ideas as to what might be wrong? Thanks!!!

Change that to
int main()
{
try
{
// place here contents of main's {...} above, but
// omit the "system(PAUSE)" and
// replace "return 0;" at the end with
return EXIT_SUCCESS;
}
catch( std::exception const& x )
{
std::cerr << "!" << x.what() << std::endl;
return EXIT_FAILURE;
}
}

--
A: Because it messes up the order in which people normally read text.
Q: Why is it such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?

[Pete C]

Protoman wrote:

string encrypted;
for(int i=0;i<cleartext.length();i++)
encrypted[i]+=(cleartext[i]+key[i%key.length()])%26;

It looks like you meant to write:

encrypted += (cleartext[i]+key[i%key.length()])%26;

and similarly in the decrypt function. Better yet, use a
std::ostringstream for efficiency.

[Protoman]

Pete C wrote:

Protoman wrote:

string encrypted;
for(int i=0;i<cleartext.length();i++)
encrypted[i]+=(cleartext[i]+key[i%key.length()])%26;

It looks like you meant to write:

encrypted += (cleartext[i]+key[i%key.length()])%26;

and similarly in the decrypt function. Better yet, use a
std::ostringstream for efficiency.

OK, how do you use an ostringstream obj?

[Pete C]

Protoman wrote:

OK, how do you use an ostringstream obj?

#include <sstream>

string decrypt(const string& ciphertext,const string& key)
{
std::ostringstream decrypted;
for(int i=0;i<ciphertext.length();i++)
decrypted.put(((ciphertext[i]-key[i%key.length()])%26));
return decrypted.str();
}
Like that. Your arithmetic needs work though, I think. Bear in mind
that subtracting one char from another can yeild a negative result, and
that your modulus will still be negative. Also, did you also mean to
use offsets from 'A'?

[Protoman]

Pete C wrote:

Protoman wrote:

OK, how do you use an ostringstream obj?

#include <sstream>

string decrypt(const string& ciphertext,const string& key)
{
std::ostringstream decrypted;
for(int i=0;i<ciphertext.length();i++)
decrypted.put(((ciphertext[i]-key[i%key.length()])%26));
return decrypted.str();
}
Like that. Your arithmetic needs work though, I think. Bear in mind
that subtracting one char from another can yeild a negative result, and
that your modulus will still be negative. Also, did you also mean to
use offsets from 'A'?

Yes, I did.

[Protoman]

Protoman wrote:

Pete C wrote:

Protoman wrote:

string encrypted;
for(int i=0;i<cleartext.length();i++)
encrypted[i]+=(cleartext[i]+key[i%key.length()])%26;

It looks like you meant to write:

encrypted += (cleartext[i]+key[i%key.length()])%26;

and similarly in the decrypt function. Better yet, use a
std::ostringstream for efficiency.

OK, how do you use an ostringstream obj?

Why would it make it more efficeient?