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Kelvin@!!!
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 Posted: Thu Feb 24, 2005 6:24 am Post subject: tokenize a string |
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hi:
in C, we can use strtok() to tokenize a char*
but i can't find any similar member function of string that can tokenize a
string
so how so i tokenize a string in C++?
do it the C way?
thanks
--
{ Kelvin@!!! }
remove the last .hk to reply
thanks
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red floyd
Guest
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| Posted: Thu Feb 24, 2005 7:34 am Post subject: Re: tokenize a string |
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Kelvin@!!! wrote:
| Quote: | hi:
in C, we can use strtok() to tokenize a char*
but i can't find any similar member function of string that can tokenize a
string
so how so i tokenize a string in C++?
do it the C way?
thanks
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Look up std::istringstream in your favorite reference book.
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ulrich
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| Posted: Thu Feb 24, 2005 7:44 am Post subject: Re: tokenize a string |
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On Thu, 24 Feb 2005 06:24:31 GMT, Kelvin@!!!
<chickenwing604-skool (AT) yahoo (DOT) com.hk.hk> wrote:
| Quote: | hi:
in C, we can use strtok() to tokenize a char*
but i can't find any similar member function of string that can tokenize
a
string
so how so i tokenize a string in C++?
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you may want to try boost::tokenizer an relatives.
http://www.boost.org/libs/tokenizer/index.html
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rossum
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| Posted: Thu Feb 24, 2005 11:14 pm Post subject: Re: tokenize a string |
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On Thu, 24 Feb 2005 06:24:31 GMT, "Kelvin@!!!"
<chickenwing604-skool (AT) yahoo (DOT) com.hk.hk> wrote:
| Quote: | hi:
in C, we can use strtok() to tokenize a char*
but i can't find any similar member function of string that can tokenize a
string
so how so i tokenize a string in C++?
do it the C way?
thanks
|
There is a sample chapter from Accelerated C++ on the web at
http://www.awprofessional.com/articles/article.asp?p=25333
The chapter has a function called split() which does what you seem to
want, it takes a string and returns a vector of all the individual
words:
// true if the argument is whitespace, false otherwise
bool space(char c) { return isspace(c); }
// false if the argument is whitespace, true otherwise
bool not_space(char c) { return !isspace(c); }
vector<string> split(const string& str) {
typedef string::const_iterator iter;
vector<string> ret;
iter i = str.begin();
while (i != str.end()) {
// ignore leading blanks
i = find_if(i, str.end(), not_space);
// find end of next word
iter j = find_if(i, str.end(), space);
// copy the characters in [i, j)
if (i != str.end()) ret.push_back(string(i, j));
i = j;
}
return ret;
}
There is a detailed explanation of the functino in the text.
rossum
--
The ultimate truth is that there is no Ultimate Truth
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davidrubin@warpmail.net
Guest
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| Posted: Fri Feb 25, 2005 2:59 am Post subject: Re: tokenize a string |
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rossum wrote:
| Quote: | // true if the argument is whitespace, false otherwise
bool space(char c) { return isspace(c); }
// false if the argument is whitespace, true otherwise
bool not_space(char c) { return !isspace(c); }
vector<string> split(const string& str) {
typedef string::const_iterator iter;
vector<string> ret;
iter i = str.begin();
while (i != str.end()) {
// ignore leading blanks
i = find_if(i, str.end(), not_space);
// find end of next word
iter j = find_if(i, str.end(), space);
// copy the characters in [i, j)
if (i != str.end()) ret.push_back(string(i, j));
i = j;
}
return ret;
}
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This would be better if it was templatized by an insertion iterator
rather than returning a vector by value. Something along the lines of
(untested)
template <typename InsertIter>
int
tokenize(const std::string& buf,
const std::string& delims,
InsertIter it)
{
std::string::size_type sp; // start position
std::string::size_type ep; // end position
int numTokens = 0;
do {
sp = buf.find_first_not_of(delims, sp);
ep = buf.find_first_of(delims, sp);
if (sp != ep) {
if (ep == buf.npos) {
ep = buf.length();
}
*it++ = buf.substr(sp, ep - sp);
++numTokens;
sp = buf.find_first_not_of(delims, ep + 1);
}
} while (sp != buf.npos);
if (sp != buf.npos) {
*it++ = buf.substr(sp, buf.length() - sp);
++numTokens;
}
return numTokens;
}
called as
std::deque<std::string> tokens;
int numTokens = tokenize(buf, delims, std::back_inserter(tokens));
/david
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