find character - GameCreators Forum

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Dimension

20

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Joined: 23rd Nov 2003

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Posted: 18th Aug 2010 01:45

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I'm creating a function to find the position of a character and for some reason it can't see when the characters are equal.

+ Code Snippet

int findCharacterPosition(char *string, char *character)
{
	for(int position = 1; position <= dbLen(string); position++)
	{
		if(dbMid(string, position) == character)
		{
			return position;
		}
	}
	
	return -1;
}

But when I modify the code as follows for some reason it works

+ Code Snippet


int findCharacterPosition(char *string, char *character)
{
	for(int position = 1; position <= dbLen(string); position++)
	{
		//Here I converted it to ASCII code
		if(dbAsc(dbMid(string, position)) == dbAsc(character))
		{
			return position;
		}
	}
	
	return -1;
}

Does anybody know why this is?

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Bran flakes91093

16

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Joined: 13th Sep 2008

Location: Crazy Land

Posted: 18th Aug 2010 01:59

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In the first code snippet, you are comparing two pointers, which are addresses in memory. You are not comparing the strings themselves, just where they are located in memory.

In the second snippet, you are comparing the strings correctly, byte by byte, but there is an easier way.

Use strcmp.

“C++ : Where friends have access to your private members.”
-Gavin Russell Baker

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Dimension

20

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Joined: 23rd Nov 2003

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Posted: 18th Aug 2010 02:39

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Thanks for the help.

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dark coder

22

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Joined: 6th Oct 2002

Location: Japan

Posted: 18th Aug 2010 06:29

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Keep in mind dbMid returns a string on the heap, so your code will leak memory. Such a function doesn't even require GDK functions, just do something like:

+ Code Snippet

int findCharacterPosition(const char *string, char character)
{
	size_t length = strlen( string );
	for ( unsigned int position = 0; position < length; position++ )
		if ( string[position] == character )
			return position;
	
	return -1;
}

Of course a better method would be to use a string class, such as std::string which has find_first_of.

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Dark GDK / find character