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Replace a Word in a .txt file

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Join Date: Feb 2008

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Re: Replace a Word in a .txt file

#11

Mar 15th, 2008

I didn´t know that the second argument was the length so now I know

I have change the code a bit though my example perheps wasn´t the best.
I do face a problem that I dont know how to solve really.
If I put the first occurence in the string with brackets like this: a4545l5l[12]
Then this code will not work to extract the number "51".
This is because I am .find("]") wich will be the first one in the string Line;
and as it takes this one into considiration, this will meen the length at the second argument in Line.find.

Is it not possible to find the next occurence of a character and then find("]") wich comes after the string stringToFind ?

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
std::string Line = "a4545l5l[12] 1Number2[51] 2Number[1]";
     int index;
     string stringToFind = "1Number2[";
     index = Line.find(stringToFind);
     index = index + stringToFind.length ();
 
	 std::string Number;
 
	 Number = Line.substr(index, (Line.find("]") - index));
 
	 fout1 << Number;
std::string Line = "a4545l5l[12] 1Number2[51] 2Number[1]";
     int index;
     string stringToFind = "1Number2[";
     index = Line.find(stringToFind);
     index = index + stringToFind.length ();

	 std::string Number;
	 	 
	 Number = Line.substr(index, (Line.find("]") - index));
	 	
	 fout1 << Number;

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Re: Replace a Word in a .txt file

#12

Mar 15th, 2008

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Originally Posted by Jennifer84

Is it not possible to find the next occurence of a character and then find("]") wich comes after the string stringToFind ?

The find() function can be told where to start the search from, see below

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
string Line = "a4545l5l[12] 1Number2[51] 2Number[1]";
string stringToFind = "1Number2[";
 
string::size_type startPos = Line.find(stringToFind);
startPos += stringToFind.length();
 
string::size_type endPos = Line.find("]", startPos);
 
string Number = Line.substr(startPos, endPos - startPos);
 
cout << Number;
string Line = "a4545l5l[12] 1Number2[51] 2Number[1]";
string stringToFind = "1Number2[";

string::size_type startPos = Line.find(stringToFind);
startPos += stringToFind.length();

string::size_type endPos = Line.find("]", startPos);

string Number = Line.substr(startPos, endPos - startPos);

cout << Number;

Remember that find() returns std::string::npos, if there is no match, so handle that case also in your code.

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Join Date: Feb 2008

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Re: Replace a Word in a .txt file

#13

Mar 15th, 2008

This did work fine and I did handle the scenario like this if there is no match for the stringToFind and it seems to work fine.

I am not really sure what ::size_type really meens ? The only thing I understand is that it is something that can handle any size of string.
Anyway this is a powerful way of searching strings. Thanks...

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
	string Line = "a4545l5l[12] 1Number2[51] 2Number[1]";
	string stringToFind = "1Number2["; 
	string::size_type startPos = Line.find(stringToFind);
	startPos += stringToFind.length(); 
	string::size_type endPos = Line.find("]", startPos); 
	string Number = Line.substr(startPos, endPos - startPos); 
 
	if( Line.find(stringToFind) != string::npos )
	{
			fout1 << Number;
	}
	string Line = "a4545l5l[12] 1Number2[51] 2Number[1]";
	string stringToFind = "1Number2["; 
	string::size_type startPos = Line.find(stringToFind);
	startPos += stringToFind.length(); 
	string::size_type endPos = Line.find("]", startPos); 
	string Number = Line.substr(startPos, endPos - startPos); 
	 	
	if( Line.find(stringToFind) != string::npos )
	{
			fout1 << Number;
	}