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

This is a discussion on my upit() using toupper() in cctype.h within the C++ Programming forums, part of the General Programming Boards category; cant get my upit() function to work! cant find anything wrong. Code: #include<iostream> #include<cctype> #include<cstring> using namespace std; class String ...

  1. #1
    Registered User xion's Avatar
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    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;
    	}
    };
    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.

  2. #2
    Just Lurking Dave_Sinkula's Avatar
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    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]);
       }
    7. It is easier to write an incorrect program than understand a correct one.
    40. There are two ways to write error-free programs; only the third one works.*

  3. #3
    Handy Andy andyhunter's Avatar
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    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!!
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  4. #4
    Registered User xion's Avatar
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    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:

  5. #5
    Registered User xion's Avatar
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    Quote 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.

  6. #6
    Just Lurking Dave_Sinkula's Avatar
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    Code:
       void upit()    //convert to uppercase if necessary
       {
          for ( char *s = str; *s; ++s )
          {
             *s = toupper(*s);
          }
       }
    7. It is easier to write an incorrect program than understand a correct one.
    40. There are two ways to write error-free programs; only the third one works.*

  7. #7
    Registered User
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    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?
    Last edited by 7stud; 02-09-2005 at 09:47 PM.

  8. #8
    Yes, my avatar is stolen anonytmouse's Avatar
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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? <<

    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.

  9. #9
    Carnivore ('-'v) Hunter2's Avatar
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    >>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.

    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?
    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]'".
    Last edited by Hunter2; 02-09-2005 at 09:48 PM.
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