find in string

[morando]

I need to find position of certain character in string, so i made a function but it doesn't do what i thought it would.
Consider this string:

std::string line = "<foo> <foo> <foo> <foo> <foo>"

I need to find position of a third '>' character so i can get:

std::string other = "<foo> <foo> <foo>";

This is my function that fails:

std::size_t find_third(const std::string& line)
{
	std::size_t pos = 0u;
	for(std::size_t i = 0; i < 3u; ++i)
	{
		std::string tmp = line.substr(pos);
		pos = tmp.find_first_of('>');
	}
	return pos;
}

Thank you for your time.

[vlad from moscow]

I have not understood what id the relation berween the third symbol '>' in the original string and

std::string other = "<foo> <foo> <foo>";

How is this string formed?

[morando]

I don't know how better to explain, my english sucks.

I have a string with 5 blocks of "stuff":

std::string line = "<blah128> <34foo> <b2ar1> <28rab11> <6a1rb>";

and i need to extract first 3 from that so that i have:

std::string other = "<blah128> <34foo> <b2ar1>";

Thank you for your time.

[Ogoyant]

How about something like:

#include <iostream>
#include <string>
using namespace std;

void findSubString(string &line, string &subString);

int main()
{
	string line = "<foo> <foo> <foo> <foo> <foo>";
	string subString;
	findSubString(line, subString);

	return 0;
}


void findSubString(string &line, string &subString)
{
	int numOfClosingBrackets = 0;
	
	for(size_t i=0; i<line.size(); i++)
	{
		subString.push_back(line[i]);

		if(line[i]=='>')
		{
			numOfClosingBrackets++;
			if(numOfClosingBrackets==3)
			{
				break;
			}
		}
	}
}

[vlad from moscow]

std::string::size_type find_third(const std::string& line)
{
	std::string::size_type pos = 0;

	for ( int i = 0; i < 3 && pos != std::string::npos; ++i )
	{
		pos = line.find( '>', pos );
		if ( pos != std::string::npos ) pos++;
	}

	return pos;
}

EDIT: I have uodated the code.

[cire]

#include <iostream>
#include <string>

std::size_t find_nth(const std::string& line, char ch, unsigned nth )
{
    std::size_t pos = line.find(ch) ;
    unsigned nFound = 1 ;

    while ( nFound < nth && pos != std::string::npos )
    {
        if ( pos+1 < line.length() )
        {
            pos = line.find('>', pos+1) ;
            ++nFound ;
        }
        else
            pos = std::string::npos ;
    }

    return pos ;
}

int main()
{
    std::string line = "<foo> <foo> <foo> <foo> <foo>" ;
    std::size_t pos = find_nth(line, '>', 3) ;

    if ( pos != std::string::npos  )
        std::cout << line.substr(0, pos+1) << '\n' ;
}

[morando]

Thank you everybody.