Caeser Code

[CNerd2121]

Well the function parameters MUST be a string and an int. That's required of me. But let's see if I got this right...

I have a string (caesar) and from this string I can have several chars, right? So how would I connect the chars to a particular string? Like if I had a program with several strings, how would I connect a char to a certain string? Or is that flexible? Would doing something like caesar[0] connect that string to the char?

And as for the ASCII values, those are already assigned with the letters and I don't need to do anything to declare that, right?

Is the * in "*cp" important?

[LB]

You can always access and change the individual characters in a string.

std::string str = "Hello";
str[0] = 'J'; //str is now "Jello" 

[CNerd2121]

OK that was a huge eye opener for me.

This is my code so far.

bool EncyptString(std::string caesar, int shift)
{
  std::getline(std::cin, caesar);
  if(std::string::npos == caesar.find_first_of(!"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")){
  for(std::size_t i = 0; i < caesar.length(); ++i){
    char &c = caesar[i];
  (((c-'a')+3)%26)+'a'}
  return true;
  std::cout << caesar << std::endl;
  }else{
  return false;
  }
}

Is it looking about right? I tried to compile it and it didn't work, but I'm curious if I'm even close to where I should be on this or if I'm way off.

Below is what the compiler gave me.

$ make
/usr/bin/g++ -Wall -Wextra -g test.cpp  -o test
test.cpp: In function ‘bool EncyptString(std::string, int)’:
test.cpp:22:103: error: call of overloaded ‘find_first_of(bool)’ is ambiguous
   if(std::string::npos == caesar.find_first_of(!"abcdefghijklmnopqrstuvwxyzABCD           EFGHIJKLMNOPQRSTUVWXYZ")){
                                                                                                                  ^
test.cpp:22:103: note: candidates are:
In file included from /usr/lib/gcc/x86_64-pc-cygwin/4.9.2/include/c++/string:52:           0,
                 from /usr/lib/gcc/x86_64-pc-cygwin/4.9.2/include/c++/bits/local           e_classes.h:40,
                 from /usr/lib/gcc/x86_64-pc-cygwin/4.9.2/include/c++/bits/ios_b           ase.h:41,
                 from /usr/lib/gcc/x86_64-pc-cygwin/4.9.2/include/c++/ios:42,
                 from /usr/lib/gcc/x86_64-pc-cygwin/4.9.2/include/c++/ostream:38           ,
                 from /usr/lib/gcc/x86_64-pc-cygwin/4.9.2/include/c++/iostream:3           9,
                 from test.cpp:8:
/usr/lib/gcc/x86_64-pc-cygwin/4.9.2/include/c++/bits/basic_string.h:1971:7: note           : std::basic_string<_CharT, _Traits, _Alloc>::size_type std::basic_string<_CharT           , _Traits, _Alloc>::find_first_of(const std::basic_string<_CharT, _Traits, _Allo           c>&, std::basic_string<_CharT, _Traits, _Alloc>::size_type) const [with _CharT =            char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>; std::bas           ic_string<_CharT, _Traits, _Alloc>::size_type = long unsigned int]
       find_first_of(const basic_string& __str, size_type __pos = 0) const
       ^
/usr/lib/gcc/x86_64-pc-cygwin/4.9.2/include/c++/bits/basic_string.h:2001:7: note           : std::basic_string<_CharT, _Traits, _Alloc>::size_type std::basic_string<_CharT           , _Traits, _Alloc>::find_first_of(const _CharT*, std::basic_string<_CharT, _Trai           ts, _Alloc>::size_type) const [with _CharT = char; _Traits = std::char_traits<ch           ar>; _Alloc = std::allocator<char>; std::basic_string<_CharT, _Traits, _Alloc>::           size_type = long unsigned int]
       find_first_of(const _CharT* __s, size_type __pos = 0) const
       ^
/usr/lib/gcc/x86_64-pc-cygwin/4.9.2/include/c++/bits/basic_string.h:2020:7: note           : std::basic_string<_CharT, _Traits, _Alloc>::size_type std::basic_string<_CharT           , _Traits, _Alloc>::find_first_of(_CharT, std::basic_string<_CharT, _Traits, _Al           loc>::size_type) const [with _CharT = char; _Traits = std::char_traits<char>; _A           lloc = std::allocator<char>; std::basic_string<_CharT, _Traits, _Alloc>::size_ty           pe = long unsigned int]
       find_first_of(_CharT __c, size_type __pos = 0) const _GLIBCXX_NOEXCEPT
       ^
test.cpp:25:23: error: expected ‘;’ before ‘}’ token
   (((c-'a')+3)%26)+'a'}
                       ^
test.cpp:25:19: warning: statement has no effect [-Wunused-value]
   (((c-'a')+3)%26)+'a'}
                   ^
test.cpp: At global scope:
test.cpp:19:43: warning: unused parameter ‘shift’ [-Wunused-parameter]
 bool EncyptString(std::string caesar, int shift)
                                           ^
test.cpp: In function ‘bool EncyptString(std::string, int)’:
test.cpp:31:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^
makefile:10: recipe for target 'test' failed
make: *** [test] Error 1

[LB]

What is that if-statement on line 4 supposed to be doing?

You always need to loop through the entire string, but you need to check whether it's a lowercase letter or uppercase letter before changing it.

[CNerd2121]

The if statement on line four is to ensure that nothing other than an alphabetical letter is entered. If something outside of the alphabet (1, 2, !, ?, %, etc.) is entered, it returns false. If the string only contains alphabetical letters, it returns true.

As for the loop, do you mean I need to create a different equation if someone enters "CODE" or "Code" instead of "code"?

[LB]

You are focusing on one letter at a time. Lowercase letters and uppercase letters need slightly different treatment.

[CNerd2121]

Yeah, I know I'm only focusing on one. I mean I need an if statement on if the letter is capital or not, right?

[LB]

Yes.

if(c >= 'a' && c <= 'z')
{
    //...
}
else if(c >= 'A' && c <= 'Z')
{
    //...
}