my upit() using toupper() in cctype.h

cant get my upit() function to work! cant find anything wrong.

Code:

---

#include<iostream>
#include<cctype>
#include<cstring>
using namespace std;

class String                //user-defined string type
{
private:
        char* str;        //pointer to string
public:
        String(char* s)
        {
                int length = strlen(s);        //length of string argument
                str = new char[length+1];        //get memory
                strcpy(str,s);        //copy string
        }

        ~String()
        {
                cout << "Deleting str.\n";
                delete[] str;
        }

        void upit()        //convert to uppercase if necessary
        {
                int length = strlen(str);
                for(int i = 0; i <= length; i++)
                        toupper(*str+i);

                //int i = 0;
                //while( *(str+i) != '\0' )
                //{
                //        toupper(*(str+i));
                //        i++;
                //}
        }

        void display()        //display the string
        {
                cout << str << endl;
        }
};

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ive made 2 attempts in the upit() both of them dont work. can anyone give me a kick in the face to the right direction? thanks in advance. :)

Assign the converted value back to the string.

Code:

---

  void upit()    //convert to uppercase if necessary
  {
      int length = strlen(str);
      for ( int i = 0; i < length; i++ )
        str[i] = toupper(str[i]);
  }

---

Well, one way to do it:

Code:

---

#include <iostream>
#include <string.h>

using std::cout;
using std::endl;
using std::cin;

int main() {

        char myString[] = "this is a test";
        char* pString;

        cout << "The message before convert: " << myString << endl;
       
        for(pString = myString; pString < myString + strlen(myString); pString++){
                *pString = toupper(*pString);
        }

        cout << "The message after convert: " << myString << endl;

        cin.get();
        return 0;
}

---

Dammit, beaten!!

lol thanks guys. didnt read carefully. toupper returns a character that has been converted. DAMMIT! details xion...details!~!~~!

Code:

---

void upit()        //convert to uppercase if necessary
        {
                for(int i = 0; i <= strlen(str); i++)
                        *(str+i) = toupper(*(str+i));
        }

---

:yanks out hair:

Quote:

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Originally Posted by anonytmouse

*(str+i) is the very ugly equivalent of str[i].

---

the book says to use pointer notation wherever possible. but yes. it is ugly.

Code:

---

  void upit()    //convert to uppercase if necessary
  {
      for ( char *s = str; *s; ++s )
      {
        *s = toupper(*s);
      }
  }

---

Ok, so I believe that a string literal is a constant in C++, and therefore you are not allowed try to change a string literal. As a result, you can't do this:

Code:

---

char* p = "some text";
cout<<p[0]<<endl; //'s'
p[1]='t';  //no compiler error but crashes program at runtime
cout<<p<<endl;

---

However, you can do this:

Code:

---

char c[20] = "other text";
c[0] = 't';
cout<<c<<endl;

---

which looks like the same thing. So, when you assign a string to a char array, is there some kind of internal strcpy() going on that copies the constant string into the char array c?

>> So, when you assign a string to a char array, is there some kind of internal strcpy() going on that copies the constant string into the char array c? <<

Yes, your deduction is exactly right. You can also use:

Code:

---

char c[] = "other text";

---

This will automatically create an array big enough to hold the string literal.

>>which looks like the same thing.
Indeed it does, but this is in fact one of the rare places that the distinction between an array and a pointer becomes apparent.

Quote:

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So, when you assign a string to a char array, is there some kind of internal strcpy() going on that copies the constant string into the char array c?

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It behaves this way at initialization, but attempting to do so at any point in the future will generate a compiler error saying "cannot convert from 'const char [5]' to 'char [5]'".