Programming Forums > Application Development > C++

uman · Jul 23rd, 2005, 1:46 AM

Is there a C++ or C standard library function that splits an std::string (or char*) into words, based on a certain delimiter? What I'm looking for is something like this:

at the beginning, line == "the big blue dog ate food."
words is an array of std::strings

whatever_function(line,words,' ');

at the end, words should equal {"the","big","blue","dog","ate","food"}

InfoGeek · Jul 23rd, 2005, 4:13 AM

strtok can work for you.

Ancient Dragon · Jul 23rd, 2005, 6:46 AM

(Toggle Plain Text)

int main(int argc, char* argv[])
{
	string str = "the big blue dog ate food.";
	int pos;
	while((pos = str.find(' ')) > 0)
	{
		string sub = str.substr(0,pos);
		str = str.substr(pos+1);
		cout << sub << endl;
	}
	
	return 0;
}

Cerulean · Jul 23rd, 2005, 6:50 AM

No, not to my knowledge. Unfortunately strtok only works with single character delimiters and it takes a const char pointer argument instead of a std::string. The less const char pointers I see in my code, the happier I tend to be

. You can also use std::getline to do this, but again that takes a single char as a delimiter.
Here's the simple function I wrote to do this.

(Toggle Plain Text)

// Returns a std::vector of the split strings
#include <vector>
#include <string>

std::vector<std::string> split(std::string str, std::string delimiter) {
    int i = 0;
    std::vector<std::string> stringvector;
    while(str.find(delimiter, i) != std::string::npos) {
        i = str.find(delimiter, i);
        stringvector.push_back(str.substr(0, i));
        str = str.substr(i + delimiter.size(), str.length() - (i + delimiter.size()));
        i += delimiter.size();
    }
    return stringvector;
}

Example usage:

(Toggle Plain Text)

int main() {
    std::string s = "This|||is|||fun|||isn't|||it";
    std::cout << split(s, "|||")[0] << "\n"; // prints 'This'
    return 0;
}

DaWei · Jul 23rd, 2005, 7:27 AM

Strtok takes multiple delimiters, but it is intended for use with arrays of char, not std strings. Furthermore, it alters the original, so even where one can use it, one may need to copy the original first. When PHP nabbed it as a utility, they burned off some of the warts.

uman · Jul 23rd, 2005, 2:17 PM

ok

getline + istringstream seems to be what I'm looking for.

Thanks all!

Shapeless · Jul 23rd, 2005, 7:21 PM

I would say boost/algorithm/string/split.hpp is what u need. its still no standart functions , but a lot of the boost libs will become standart in the 0x10 c++ standart and i m pretty sure that the string-algo lib will...
btw boost is so powerfull u should have a look or even learn to handle some parts.

like boost::split
the function gets a sequence,a collection and a prdicate, and an so called token compress mode type, but u dont need that one.
so for your purposes it would look like this

(Toggle Plain Text)

template<typename SequenceSequenceT, typename CollectionT, 
             typename PredicateT> 
      SequenceSequenceT & 
      split(SequenceSequenceT &, CollectionT &, PredicateT, 
            token_compress_mode_type = token_compress_off);

or shorter:

(Toggle Plain Text)

      split(SequenceSequenceT &, CollectionT &, PredicateT);

where for example the collections is a std::string and the sequence is a std::vector<std::string>
id just wrote this little testmain. i think its exactly what you ask for:

(Toggle Plain Text)

#include<iostream>
#include<string>
#include<vector>
#include<boost/algorithm/string.hpp>

#include<algorithm>//test output
#include<iterator>// test output


int main() {
	std::string line("hallo-this-is-a-string");
	std::vector<std::string> result;
	boost::split(result,line,boost::is_any_of("-"));
                       // puts the result of a split of line into the 
                       // result container without things that match to the prediate
                       //"-" or in your case " "
	if(!result.empty())
		std::copy(result.begin(),result.end(),std::ostream_iterator<std::string>(std::cout,"\n"));
	return 0;
}

so here is the compare:

(Toggle Plain Text)

your wish:
function(container,string,delim);
solution:
split(container,string,predicate); where predicate is the delim...

as you can see its exactly the same u ask for. but since it is a template u
can use it on every containers convertable to each other.

DaWei · Jul 23rd, 2005, 9:12 PM

Quote:

I would say boost/algorithm/string/split.hpp is what u need. its still no standart functions , but a lot of the boost libs will become standart in the 0x10 c++ standart and i m pretty sure that the string-algo lib will...

Get real.

Ancient Dragon · Jul 23rd, 2005, 9:26 PM

The problem posted by OP is so simple -- Forget about using all those other complex templates that do nothing more than make the solution to the problem more complicated. You guys are making such a complicated solution out of something that is very trivel. :eek:

stevengs · Jul 24th, 2005, 6:04 AM

Quote:

Originally Posted by Ancient Dragon

The problem posted by OP is so simple -- Forget about using all those other complex templates that do nothing more than make the solution to the problem more complicated. You guys are making such a complicated solution out of something that is very trivel. :eek:

Yeah, I think I would go with std::string methods too.

Jul 23rd, 2005, 1:46 AM	#1
uman Expert Programmer Join Date: Dec 2004 Posts: 794 Rep Power: 4	"split" function Is there a C++ or C standard library function that splits an std::string (or char*) into words, based on a certain delimiter? What I'm looking for is something like this: at the beginning, line == "the big blue dog ate food." words is an array of std::strings whatever_function(line,words,' '); at the end, words should equal {"the","big","blue","dog","ate","food"} __________________ Few people deserve to be compared to (Rush) Limbaugh, most of them were convicted at the Nuremburg trials. --WilliamSChips on Slashdot

Jul 23rd, 2005, 4:13 AM	#2
InfoGeek Professional Programmer Join Date: Jun 2005 Location: India, The great. Posts: 435 Rep Power: 4	strtok can work for you. __________________ PFO - My daily dose of technology.

Jul 23rd, 2005, 6:46 AM	#3
Ancient Dragon PFO God In Training Join Date: Jun 2005 Location: near St Louis, MO. (USA) Posts: 489 Rep Power: 4	(Toggle Plain Text) int main(int argc, char* argv[]) { string str = "the big blue dog ate food."; int pos; while((pos = str.find(' ')) > 0) { string sub = str.substr(0,pos); str = str.substr(pos+1); cout << sub << endl; } return 0; } int main(int argc, char* argv[]) { string str = "the big blue dog ate food."; int pos; while((pos = str.find(' ')) > 0) { string sub = str.substr(0,pos); str = str.substr(pos+1); cout << sub << endl; } return 0; }

Jul 23rd, 2005, 6:50 AM	#4
Cerulean Professional Programmer Join Date: Apr 2005 Location: London, England Posts: 459 Rep Power: 4	No, not to my knowledge. Unfortunately strtok only works with single character delimiters and it takes a const char pointer argument instead of a std::string. The less const char pointers I see in my code, the happier I tend to be . You can also use std::getline to do this, but again that takes a single char as a delimiter. Here's the simple function I wrote to do this. (Toggle Plain Text) // Returns a std::vector of the split strings #include <vector> #include <string> std::vector<std::string> split(std::string str, std::string delimiter) { int i = 0; std::vector<std::string> stringvector; while(str.find(delimiter, i) != std::string::npos) { i = str.find(delimiter, i); stringvector.push_back(str.substr(0, i)); str = str.substr(i + delimiter.size(), str.length() - (i + delimiter.size())); i += delimiter.size(); } return stringvector; } // Returns a std::vector of the split strings #include <vector> #include <string> std::vector<std::string> split(std::string str, std::string delimiter) { int i = 0; std::vector<std::string> stringvector; while(str.find(delimiter, i) != std::string::npos) { i = str.find(delimiter, i); stringvector.push_back(str.substr(0, i)); str = str.substr(i + delimiter.size(), str.length() - (i + delimiter.size())); i += delimiter.size(); } return stringvector; } Example usage: (Toggle Plain Text) int main() { std::string s = "This\|\|\|is\|\|\|fun\|\|\|isn't\|\|\|it"; std::cout << split(s, "\|\|\|")[0] << "\n"; // prints 'This' return 0; } int main() { std::string s = "This\|\|\|is\|\|\|fun\|\|\|isn't\|\|\|it"; std::cout << split(s, "\|\|\|")[0] << "\n"; // prints 'This' return 0; }

Jul 23rd, 2005, 7:27 AM	#5
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	Strtok takes multiple delimiters, but it is intended for use with arrays of char, not std strings. Furthermore, it alters the original, so even where one can use it, one may need to copy the original first. When PHP nabbed it as a utility, they burned off some of the warts. __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

Jul 23rd, 2005, 2:17 PM	#6
uman Expert Programmer Join Date: Dec 2004 Posts: 794 Rep Power: 4	ok getline + istringstream seems to be what I'm looking for. Thanks all! __________________ Few people deserve to be compared to (Rush) Limbaugh, most of them were convicted at the Nuremburg trials. --WilliamSChips on Slashdot

Jul 23rd, 2005, 7:21 PM	#7
Shapeless Programmer Join Date: Jul 2005 Location: germany/hamburg Posts: 32 Rep Power: 0	I would say boost/algorithm/string/split.hpp is what u need. its still no standart functions , but a lot of the boost libs will become standart in the 0x10 c++ standart and i m pretty sure that the string-algo lib will... btw boost is so powerfull u should have a look or even learn to handle some parts. like boost::split the function gets a sequence,a collection and a prdicate, and an so called token compress mode type, but u dont need that one. so for your purposes it would look like this (Toggle Plain Text) template<typename SequenceSequenceT, typename CollectionT, typename PredicateT> SequenceSequenceT & split(SequenceSequenceT &, CollectionT &, PredicateT, token_compress_mode_type = token_compress_off); template<typename SequenceSequenceT, typename CollectionT, typename PredicateT> SequenceSequenceT & split(SequenceSequenceT &, CollectionT &, PredicateT, token_compress_mode_type = token_compress_off); or shorter: (Toggle Plain Text) split(SequenceSequenceT &, CollectionT &, PredicateT); split(SequenceSequenceT &, CollectionT &, PredicateT); where for example the collections is a std::string and the sequence is a std::vector<std::string> id just wrote this little testmain. i think its exactly what you ask for: (Toggle Plain Text) #include<iostream> #include<string> #include<vector> #include<boost/algorithm/string.hpp> #include<algorithm>//test output #include<iterator>// test output int main() { std::string line("hallo-this-is-a-string"); std::vector<std::string> result; boost::split(result,line,boost::is_any_of("-")); // puts the result of a split of line into the // result container without things that match to the prediate //"-" or in your case " " if(!result.empty()) std::copy(result.begin(),result.end(),std::ostream_iterator<std::string>(std::cout,"\n")); return 0; } #include<iostream> #include<string> #include<vector> #include<boost/algorithm/string.hpp> #include<algorithm>//test output #include<iterator>// test output int main() { std::string line("hallo-this-is-a-string"); std::vector<std::string> result; boost::split(result,line,boost::is_any_of("-")); // puts the result of a split of line into the // result container without things that match to the prediate //"-" or in your case " " if(!result.empty()) std::copy(result.begin(),result.end(),std::ostream_iterator<std::string>(std::cout,"\n")); return 0; } so here is the compare: (Toggle Plain Text) your wish: function(container,string,delim); solution: split(container,string,predicate); where predicate is the delim... your wish: function(container,string,delim); solution: split(container,string,predicate); where predicate is the delim... as you can see its exactly the same u ask for. but since it is a template u can use it on every containers convertable to each other. __________________ of all the things he has lost, i think he misses his mind the most typedef typename pizza_t<oven_policy<225,12.5>,ingredient_policy<salami,mushroom,cheese> > Pizza;

Jul 23rd, 2005, 9:26 PM	#9
Ancient Dragon PFO God In Training Join Date: Jun 2005 Location: near St Louis, MO. (USA) Posts: 489 Rep Power: 4	The problem posted by OP is so simple -- Forget about using all those other complex templates that do nothing more than make the solution to the problem more complicated. You guys are making such a complicated solution out of something that is very trivel. :eek: Last edited by Ancient Dragon; Jul 23rd, 2005 at 9:39 PM.

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Programming Forums > Application Development > C++

"split" function