| re: trouble splitting strings
Aaron Walker wrote:
[color=blue]
> I have a feeling this going to end up being something so stupid, but
> right now I'm confused as hell.
>
> I'm trying to code a function, that given a string and a delimiter
> char, returns a vector of the sub-strings.
>
> Here's what I have (I've thrown a main() in there for this mail).
> ---
> #include <iostream>
> #include <string>
> #include <vector>
>
> std::vector<std::string>
> splitstr(const std::string &str, const char delim)
> {
> std::vector<std::string> vec;
>
> std::string::size_type pos, lpos = 0;
>
> while (true)
> {
> pos = str.find(delim, lpos);
> if (pos == std::string::npos)
> {
> vec.push_back(str.substr(lpos));
> break;
> }
>
> vec.push_back(str.substr(lpos, pos));
> lpos = ++pos;
> }
> return vec;
> }
>
> int
> main(int argc, char **argv)
> {
> if (argc != 2)
> return 1;
>
> std::vector<std::string> testvec = splitstr(argv[1], ' ');
>
> std::cout << "testvec1 = [";
>
> std::vector<std::string>::iterator i;
> for (i = testvec.begin() ; i != testvec.end() ; ++i)
> std::cout << "'" << *i << "', ";
> std::cout << "]" << std::endl;
> }
> ---
>
> For some reason I cannot figure out, it's doing this:
>
> $ ./splitstr "this is a test"
> testvec1 = [ 'this', 'is a te', 'a test', 'test', ]
>
> It looks like lpos is correct for every one, but pos is only correct
> for the first and last elements.
>
> When printing the value of pos and lpos on each iteration, it looks
> correct. For example, the 2nd element in the vector above is lpos=5,
> pos=7. How on earth can that equal a 7char string?
>
> Anyone able to give me a kind shove in the right direction?[/color]
Here's a version that I wrote some time back. I've seen other
variations posted here that use a stringstream and read from it.
#include <vector>
#include <string>
// breaks apart a string into substrings separated by a character string
// does not use a strtok() style list of separator characters
// returns a vector of std::strings
std::vector<std::string> Explode (const std::string &inString,
const std::string &separator)
{
std::vector<std::string> returnVector;
std::string::size_type start = 0;
std::string::size_type end = 0;
while ((end=inString.find (separator, start)) != std::string::npos)
{
returnVector.push_back (inString.substr (start, end-start));
start = end+separator.size();
}
returnVector.push_back (inString.substr (start));
return returnVector;
}
Brian
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