Mid(), Left(), InStr() and other functions like in VB? 1

[hvytas]

Hello for all C++ programmers,

I think we write the fastest and smallest code requare for manipulating with strings like done in VB (Visual Basic).
If somebody know how to write other functions that work faster (like with ASM or C++) and use less code, add to this thread.

copy mid point from string

string Mid(string& str, int pos1, int pos2)
{
	int i;
	string temp = "";
	for(i = pos1; i < pos2; i++)
	{
		temp += str[i];
	}

	return temp;
}

copy mid point vb style (pos + length)

string vMid(string& str, int pos1, int length)
{
	int i;
	string temp = "";
	for(i = pos1; i < pos1+length; i++)
	{
		temp += str[i];
	}
	return temp;
}

copy from left of pos

string Left(string& str, int pos)
{
	int i;
	string temp = "";
	for(i = 0; i < pos; i++)
	{
		temp += str[i];
	}

	return temp;
}

copy from right of pos

string Right(string& str, int pos)
{
	int i;
	string temp = "";
	for(i = pos; i < strlen(str.c_str()); i++)
	{
		temp += str[i];
	}
	return temp;
}

lowercase the string

string Lcase(string& str)
{
	int i;
	string temp = "";
	for(i = 0; i < str.length(); i++)
	{
		temp += tolower(str[i]);
	}
	return temp;
}

uppercase the string

string Ucase(string& str)
{
	int i;
	string temp = "";
	for(i = 0; i < str.length(); i++)
	{
		temp += toupper(str[i]);
	}
	return temp;
}

How to do InStr(), InStrRev() or other functions add if you know.

 

[ArkM]

Obviously, these left/mid/right etc functions are cumbersome surrogates of std::substr (i.e. invention of the wheel).
Case translations with (by definition) ineffective +=? Better use local string copy (initialized by ctor) then change its buffer directly via const_cast<char*>(c_ptr()) pointer (then return it).

 

[Cagliostro]

How about using std::string?

Ion Filipski

 

[hvytas]

Fine, this is std edition:]
If somebody know how to write shorter add to this thread.

InStrRev

int CGlobal::InStrRev(string str, string what)
{
	// int InStrRev(start-1, str, what)
	return str.find_last_of(what) + 1;
}

InStr, if return -1 that is wrong pos, default pos=0

int CGlobal::InStr(string str, string what, int pos)
{
	// int InStr(start-1, str, what)
	if (pos >= 0)
	{
		if (pos == 0)
		{
			return str.find_first_of(what) + 1; 
		}else{
			return str.find_first_of(what, pos) + 1;
		};
	}else{
		return -1;
	};
}

copy mid point from string (NEW*)

string CGlobal::Mid2(string str, int pos1, int pos2)
{
	string sFind = "";
	if (pos1 >= 0)
	{
		sFind.assign(str, pos1, pos2); // 0..n
	};
	return sFind;
}

This functions translated from VB for easy use string manipulation in C++ or use C++ in VB and etc.

 

[ArkM]

or use C++ in VB?..
You can't use C++ std::string in VB b-string environment.

But what for these exercises at all? I think the C++ std;;string class has much more features than VB strings...

 

[cpjust]

string CGlobal::Mid( const string& str, string::size_type pos1, string::size_type pos2 ) const
{
    return str.substr( pos1, pos2 );
}

string::size_type CGlobal::InStr( const string& str, const string& what, string::size_type pos ) const
{
    return str.find( what.c_str(), pos );
}

 

[Cagliostro]

I guess all of you missunderstood me. std::string has all needed functionality to work with string as easy as in basic:

[COLOR=blue]#include[/color]<windows.h>
[COLOR=blue]#include[/color]<iostream>
[COLOR=blue]#include[/color]<string>

[COLOR=blue]using namespace[/color] std;

[COLOR=blue]int[/color] main()
{
  string x = "hello to my world";
  string y;
  cout<< "x = "<< x<< endl;

  y = x.substr(0, 5); [COLOR=green]//0 = left[/color]
  cout<< "y = left(x, 5): "<< y<< endl;

  y = x.substr(6, 2);
  cout<< "y = mid(x, 6, 2): "<< y<< endl;

  y = x.substr(9, 2);
  cout<< "y = mid(x, 9, 2): "<< y<< endl;

  y = x.substr(12, 5);
  cout<< "y = mid(x, 12, 5): "<< y<< endl;

  y = x.substr(9, 2);
  cout<< "y = mid(x, 9, 2): "<< y<< endl;

  [COLOR=green]//get from some position without number of 
  //chars needed
  //gets the string from the pos to end of string[/color]
  y = x.substr(9);
  cout<< "y = x from 9 to EOS: "<< y<< endl;

  [COLOR=green]//get from some position without number of 
  //chars needed
  //also means right, if you calculate it 
  //from the end if string
  // -1 needed because C++ uses 0 based indexes[/color]
  y = x.substr(x.length() - 1 - 5);
  cout<< "y = rigth(x, 5): "<< y<< endl;
[COLOR=green]
  //basic string is UNICODE, so use wide string
  //look at w prefix for string and cout[/color]
  wstring wx = L"hello world";
  wcout<< wx<< endl;

[COLOR=green]  //basic string:[/color]
  BSTR bstr = SysAllocString(wx.c_str());
  wcout<< bstr<< endl;
  SysFreeString(bstr);
  return 0;
}

this is the console output:

x = hello to my world
y = left(x, 5): hello
y = mid(x, 6, 2): to
y = mid(x, 9, 2): my
y = mid(x, 12, 5): world
y = mid(x, 9, 2): my
y = x from 9 to EOS: my world
y = rigth(x, 5):  world
hello world
hello world

Ion Filipski

 

[MakeItSo]

Nice one, Ion!
Have a star!

:-D

Thanks!
Andy

[blue]Speak out against Human Rights violations in China/Tibet

http://www.thepetitionsite.com/takeaction/323661827

[/blue]