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Splitting a string in C++
In PHP, the explode() function will take a string and chop it up into an array separating each element by a specified delimiter.
Is there an equivalent function in C++?
2 Answers
Here's a simple example implementation:
#include <string> #include <vector> #include <sstream> #include <utility> std::vector<std::string> explode(std::string const & s, char delim) { std::vector<std::string> result; std::istringstream iss(s); for (std::string token; std::getline(iss, token, delim); ) { result.push_back(std::move(token)); } return result; } Usage:
auto v = explode("hello world foo bar", ' '); Note: @Jerry's idea of writing to an output iterator is more idiomatic for C++. In fact, you can provide both; an output-iterator template and a wrapper that produces a vector, for maximum flexibility.
Note 2: If you want to skip empty tokens, add if (!token.empty()).
8 Comments
Kerrek SB
@user1944429: The move avoids copying the string data. Since you have no more use for it inside the loop, it makes sense for the vector to "steal" that data directly without copying it.
Alok Saini
it misses a case, in the input scenario of "a,b,c,d," it should return 5 values including the last null, but it do not
Alok Saini
if need that here what i used, explode_cpp
Kerrek SB
@AlokSaini: True, the present code has "optional trailing delimiter" semantics rather than what you wanted. The easiest way to fix this would be to add a check if
s.back() == delim and emit another empty string in that case. |
The standard library doesn't include a direct equivalent, but it's a fairly easy one to write. Being C++, you don't normally want to write specifically to an array though -- rather, you'd typically want to write the output to an iterator, so it can go to an array, vector, stream, etc. That would give something on this general order:
template <class OutIt> void explode(std::string const &input, char sep, OutIt output) { std::istringstream buffer(input); std::string temp; while (std::getline(buffer, temp, sep)) *output++ = temp; } 
4 Comments
AntonioCS
I believe there is an error in the
std::getline call. Where you have input I believe it should be temp
Jerry Coffin
@AntonioCS: Oops, quite right. Thank you!
pacmaninbw
How would you handle all white space as a separator?
Jerry Coffin
@pacmaninbw: One obvious possibility would be to change the while loop to
while (buffer >> temp).
boost::splitfrom [boost/algorithm/string.hpp](www.boost.org/doc/html/string_algo.html)