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Check string[i] for content [message #34460]

Wed, 23 November 2011 13:51

Wolfgang
Messages: 146
Registered: November 2011
Location: Germany

Experienced Member

Hello,

i try to make something like a parser....

void curve::term_op1(String &term, String &newterm, int &pos)
{
	String justOne = term.Mid(pos,1);
	
	if (justOne.IsEqual("+"))
	{
		newterm << " + ";
		pos++;
	} else if (justOne.IsEqual("-"))
	{
		newterm << " - ";
		pos++;
	} else
	{
		if (IsDigit(justOne))
		{ /* should trigger if it is a number 0-9) */
			newterm << " INT (" << justOne << ") ";
			pos++;
		} else
		{
			newterm << " Something else (" << justOne << ") ";
			pos++;	
		}
	}
}

Of course the "IsDigit" does not work.... can someone tell me how to do this... maybe without a String with 1 character in it (i think its really bad to do it this way?)

Thanks!

Best regards,
Wolfgang

[Updated on: Wed, 23 November 2011 13:52]

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Re: Check string[i] for content [message #34461 is a reply to message #34460]

Wed, 23 November 2011 14:06

cbpporter
Messages: 1401
Registered: September 2007

Ultimate Contributor

If you are doing it this way, why not use character based comparison. A string with length 1 is completely different from a character:

void term_op1(String &term, String &newterm, int &pos)
{
	char justOne = term[pos];
	
	if (justOne == '+')
	{
		newterm << " + ";
		pos++;
	} else if (justOne == '-')
	{
		newterm << " - ";
		pos++;
	} else
	{
		if (IsDigit(justOne))
		{ /* should trigger if it is a number 0-9) */
			newterm << " INT (" << justOne << ") ";
			pos++;
		} else
		{
			newterm << " Something else (" << justOne << ") ";
			pos++;	
		}
	}
}

Also, check out CParser class. It is very powerful.

PS: I did not check you code, only made it compile Smile

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Re: Check string[i] for content [message #34462 is a reply to message #34461]

Wed, 23 November 2011 14:10

Wolfgang
Messages: 146
Registered: November 2011
Location: Germany

Experienced Member

thank you for your help.... its not really a project with the aim to make things easy, its just for me to improve my skills.

At least my first step is to check a mathematic term for validity..

Thanks for the hint with the char, I don't know why but I looked for something like IsEqual for char ---> stupid Very Happy

Asked myself how to compare a char to something..

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