Reversing A String?

This is a discussion on Reversing A String? within the C++ Programming forums, part of the General Programming Boards category; I need to know how to reverse a string using C++? I have been told the best way to do ...

  1. #1
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    Question Reversing A String?

    I need to know how to reverse a string using C++?

    I have been told the best way to do this is by using Pointers but I am unable to find a way to make it work.

    And, yes I am aware there is probably a really easy way to do this but my brain isn't working.

  2. #2
    Normal vector Carlos's Avatar
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    Budapest
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    Hi,
    using MFC(CString) but same algorythm should work for other strings, too.

    (except index might be zero-based)
    --------------------the function-----
    CString CReverseStringDlg::ReverseString( CString* string_in )
    {
    CString aTempString;

    unsigned int aStrlen = string_in->GetLength();
    TCHAR ch;
    for ( unsigned int i = 1; i <= aStrlen; i++ )
    {
    ch = string_in->GetAt( aStrlen - i );
    aTempString.Insert( i, ch );
    }

    return ( aTempString );
    }

    --------------------the call------------
    CString aString;

    aString = "123456789";
    aString = ReverseString( &aString );

    // now aString is "987654321"
    Have fun.

  3. #3
    Registered User
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    Hi. Thanks for the quick reply. I actually managed to find a soloution of my own :-)

    If your interested;


    void displayinreverse()
    {
    cout << "The Text Reversed Is: ";
    string name = line; // line is the variable used in the cin
    int nLength=name.length();
    for (int i=nLength-1;i>=0;i--)
    cout << line[i];
    cout << endl;
    }

    Thanks again for your help though :-)

  4. #4
    Registered User WayTooHigh's Avatar
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    Aug 2001
    Posts
    101
    using strrev function...
    Code:
    #include<iostream.h>
    #include<string.h>
    
    int main()
    {
    	char bud[255];
    
    	cout<<"Enter a string\n";
    	cin.getline(bud, 255, '\n');
    
    	cout<<"\nString before reversal: \n";
    	cout<<bud;
    	cout<<"\n";
    	
    	strrev(bud);
    
    	cout<<"\nString after reversal: \n";
    	cout<<bud;
    	cout<<"\n";
    
    	return 0;
    }
    using a loop...
    Code:
    #include<iostream.h>
    #include<string.h>
    
    int main()
    {
    	char BAK[255]="", bud[255]="";
    	int h,i;
    
    	cout<<"Enter a string\n";
    	cin.getline(bud, 254,'\n');
    
    	cout<<"\nString before reversal: \n";
    	cout<<bud;
    	cout<<"\n";
    
    
    	i = strlen(bud);
    	for(h=0; i>0; i--)
    	{
    		BAK[h] = bud[i-1];
    		h++;
    	}
    
    	cout<<"\nString after reversal: \n";
    	cout<<BAK;
    	return 0;
    }
    Sometimes, the farthest point from the center is the center itself.

    Your life is your canvas, it's only as beautiful as you paint it.

  5. #5
    Skunkmeister Stoned_Coder's Avatar
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    Posts
    2,572
    heres how to do it with pointers....
    Code:
    void Reverse(char* pData)
    
    {
    	char temp; //holding area
    	int Length=strlen(pData);
                    char* start=pData; //first char
    	char* last=pData+Length-1;//last char before null
    	while (start<last) // stops at midpoint
    		{
    			temp=*start;
    			*start=*last;
    			*last=temp;
    			++start;
    			--last;
    		}
    }
    Free the weed!! Class B to class C is not good enough!!
    And the FAQ is here :- http://faq.cprogramming.com/cgi-bin/smartfaq.cgi

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