extract first word in a string

[lnknprkn]

user input: **HELLO**!!

what's suppose to happen:
firstWord = HELLO
inspectThis = **!!

string extractWord (string& inspectThis)
{
	string firstWord;
	int i = 0;

	while (inspectThis[i] != '\n')
	{
		if (isalpha(inspectThis[i]))
		{
			firstWord += inspectThis[i];
			inspectThis[i] = NULL;
		}
		inspectThis[i] = NULL;
		i++;
	}
	return firstWord;
}

this is what i have so far and right now i'm stuck

[Pravin Kumar]

Hello,

Normally, a word is defined as the first group of characters before the first whitespace character. In your problem, you mean it as the first group of alphabets. Am I right?

It is clear that your logic does not result in what you want. Think this way: Check for each character whether it is alphabet or non-alphabet. If you get an alphabet, add it to the first word. If you do not get an alphabet, there can be two cases: (i) you already have a word filled or (ii) you do not have a word. In the first case, terminate the function and return the word. In the second case advance to the next character.

Here is a simple code which does what is explained above, which comes in place of the while loop in your code:

for (int count = 0; count < inspectThis.length(); count++)
	if (isalpha(inspectThis[count]))
		firstWord += inspectThis[count];
	else if (firstWord.length() > 0)
		break;

Once you find the first word, you can check its position in the main string inspectThis and remove that word.

int pos = inspectThis.find(firstWord);
inspectThis.erase(pos, pos + firstWord.length());

Hope it is clear.

Regards,
Pravin.

[Mike Harnad]

Have a look at AfxExtractSubString .

[Philip Nicoletti]

1) There is rarely a circumstance when you would set the value
to an individual character in a std:;string to NULL. So your logic
would be suspect right there.

2) The algorithm to use :

a) find the first alphabetic character.

b) Since you only want the first word, you would start with that character
and go until you reach a non-alphabetic character.

3) using the standard library, the function almost writes itself (although
the way to find the non-alphabetic character is not obvious).

#include <string>
#include <iostream>
#include <algorithm>
#include <functional>
#include <cctype>


std::string FirstWord(const std::string & s)
{
    using namespace std;

    string::const_iterator it1 = find_if(s.begin(),s.end(),::isalpha);
    string::const_iterator it2 = find_if(it1,s.end(),not1(ptr_fun(::isalpha)));
    
    return string(it1,it2);
}

int main()
{
    std::string s = "***!  abc  sxyz**";

    std::cout << FirstWord(s) << "\n";

    return 0;
}