Split a string into a vector in C++

This post will discuss how to split a string into a vector in C++.

1. Using String Stream

A simple solution to split a space-separated std::string into a std::vector<string> is using string streams. This can be implemented as follows in C++.

#include <iostream>

#include <vector>

#include <algorithm>

#include <sstream>

#include <iterator>

int main()

{

std::string s = "C C++ Java";

std::stringstream ss(s);

std::istream_iterator<std::string> begin(ss);

std::istream_iterator<std::string> end;

std::vector<std::string> tokens(begin, end);

for (auto &s: tokens) {

std::cout << s << std::endl;

}

return 0;

}

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Output:

C
C++
Java

To split a string using a delimiter, we can invoke the getline() function with delimiter:

#include <iostream>

#include <vector>

#include <algorithm>

#include <sstream>

#include <iterator>

int main()

{

std::string s = "C,C++,Java";

std::vector<std::string> tokens;

std::string token;

std::stringstream ss(s);

while (getline(ss, token, ',')){

tokens.push_back(token);

}

for (auto &s: tokens) {

std::cout << s << std::endl;

}

return 0;

}

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Output:

C
C++
Java

2. Using `string::find_first_not_of`

We can use a combination of string::find_first_not_of and string::find functions to split a string in C++ into a vector. The following C++ program demonstrates its usage:

#include <iostream>

#include <vector>

#include <algorithm>

#include <sstream>

#include <iterator>

std::vector<std::string> split(std::string const &str, char delim) {

std::vector<std::string> tokens;

size_t start;

size_t end = 0;

while ((start = str.find_first_not_of(delim, end)) != std::string::npos) {

end = str.find(delim, start);

tokens.push_back(str.substr(start, end - start));

}

return tokens;

}

int main()

{

std::string s = "C,C++,Java";

std::vector<std::string> tokens = split(s, ',');

for (auto &s: tokens) {

std::cout << s << std::endl;

}

return 0;

}

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Output:

C
C++
Java

3. Using Boost

Another good alternative is to use boost’s string algorithms library. It contains the boost::split function to splits the input into parts separated by a delimiter.

#include <iostream>

#include <vector>

#include <boost/algorithm/string/classification.hpp>

#include <boost/algorithm/string/split.hpp>

int main()

{

std::string s = "C, C++, Java";

std::vector<std::string> tokens;

boost::split(tokens, s, boost::is_any_of(", "), boost::token_compress_on);

for (auto &s: tokens) {

std::cout << s << std::endl;

}

return 0;

}

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Output:

C
C++
Java

That’s all about splitting a string into a vector in C++.

Split a string into a vector in C++

1. Using String Stream

2. Using string::find_first_not_of

3. Using Boost

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2. Using `string::find_first_not_of`