How do I tokenize a string in C++?

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Java has a convenient split method:

String str = "The quick brown fox";
String[] results = str.split(" ");

Is there an easy way to do this in C++?


C++ standard library algorithms are pretty universally based around iterators rather than concrete containers. Unfortunately this makes it hard to provide a Java-like split function in the C++ standard library, even though nobody argues that this would be convenient. But what would its return type be? std::vector<std::basic_string<…>>? Maybe, but then we’re forced to perform (potentially redundant and costly) allocations.

Instead, C++ offers a plethora of ways to split strings based on arbitrarily complex delimiters, but none of them is encapsulated as nicely as in other languages. The numerous ways fill whole blog posts.

At its simplest, you could iterate using std::string::find until you hit std::string::npos, and extract the contents using std::string::substr.

A more fluid (and idiomatic, but basic) version for splitting on whitespace would use a std::istringstream:

auto iss = std::istringstream{"The quick brown fox"};
auto str = std::string{};

while (iss >> str) {
    process(str);
}

Using std::istream_iterators, the contents of the string stream could also be copied into a vector using its iterator range constructor.

Multiple libraries (such as Boost.Tokenizer) offer specific tokenisers.

More advanced splitting require regular expressions. C++ provides the std::regex_token_iterator for this purpose in particular:

auto const str = "The quick brown fox"s;
auto const re = std::regex{R"(\s+)"};
auto const vec = std::vector<std::string>(
    std::sregex_token_iterator{begin(str), end(str), re, -1},
    std::sregex_token_iterator{}
);

C library function - strtok(), The C library function char *strtok(char *str, const char *delim) breaks string str into a series of tokens using the delimiter delim. Declaration. Following is the  Tokenizing a string denotes splitting a string with respect to a delimiter. There are many ways we can tokenize a string. Let’s see each of them: A stringstream associates a string object with a stream allowing you to read from the string as if it were a stream. // Splits str [] according to given delimiters. // and returns next token.


The Boost tokenizer class can make this sort of thing quite simple:

#include <iostream>
#include <string>
#include <boost/foreach.hpp>
#include <boost/tokenizer.hpp>

using namespace std;
using namespace boost;

int main(int, char**)
{
    string text = "token, test   string";

    char_separator<char> sep(", ");
    tokenizer< char_separator<char> > tokens(text, sep);
    BOOST_FOREACH (const string& t, tokens) {
        cout << t << "." << endl;
    }
}

Updated for C++11:

#include <iostream>
#include <string>
#include <boost/tokenizer.hpp>

using namespace std;
using namespace boost;

int main(int, char**)
{
    string text = "token, test   string";

    char_separator<char> sep(", ");
    tokenizer<char_separator<char>> tokens(text, sep);
    for (const auto& t : tokens) {
        cout << t << "." << endl;
    }
}

Tokenizing strings in C, Do it like this: char s[256]; strcpy(s, "one two three"); char* token = strtok(s, " "); while (token) { printf("token: %s\n", token); token = strtok(NULL, " "); }. Note: strtok​  strtok accepts two strings - the first one is the string to split, the second one is a string containing all delimiters. In this case there is only one delimiter. strtok returns a pointer to the character of next token. So the first time it is called, it will point to the first word. char *ptr = strtok (str, delim);


Here's a real simple one:

#include <vector>
#include <string>
using namespace std;

vector<string> split(const char *str, char c = ' ')
{
    vector<string> result;

    do
    {
        const char *begin = str;

        while(*str != c && *str)
            str++;

        result.push_back(string(begin, str));
    } while (0 != *str++);

    return result;
}

Tokenizing a string in C++, Tokenizing a string in C++. Tokenizing a string denotes splitting a string with respect to a delimiter. There are many ways we can tokenize a string. Let's see each  A quick keyword search via Google for tokenize string c++ carried out on 06 Mar 2019 @ 13 55 hrs GMT has just returned 76,500 results. The following, taken from the results, should be more than enough to get you started: * Tokenizing a string in C


Use strtok. In my opinion, there isn't a need to build a class around tokenizing unless strtok doesn't provide you with what you need. It might not, but in 15+ years of writing various parsing code in C and C++, I've always used strtok. Here is an example

char myString[] = "The quick brown fox";
char *p = strtok(myString, " ");
while (p) {
    printf ("Token: %s\n", p);
    p = strtok(NULL, " ");
}

A few caveats (which might not suit your needs). The string is "destroyed" in the process, meaning that EOS characters are placed inline in the delimter spots. Correct usage might require you to make a non-const version of the string. You can also change the list of delimiters mid parse.

In my own opinion, the above code is far simpler and easier to use than writing a separate class for it. To me, this is one of those functions that the language provides and it does it well and cleanly. It's simply a "C based" solution. It's appropriate, it's easy, and you don't have to write a lot of extra code :-)

String Split - How to play with strings in C, The words are separated by space. So space will be our delimiter. char delim[] = " ";. strtok accepts two strings -  from nltk import word_tokenize sent = "This is my text, this is a nice way to input text." word_tokenize(sent) If your sentence is truly simple enough: Using the string.punctuation set, remove punctuation then split using the whitespace delimiter: import string x = "This is my text, this is a nice way to input text." y = "".join( [i for i in x


Another quick way is to use getline. Something like:

stringstream ss("bla bla");
string s;

while (getline(ss, s, ' ')) {
 cout << s << endl;
}

If you want, you can make a simple split() method returning a vector<string>, which is really useful.

How I tokenize a string (char array) in C, How I tokenize a string (char array) in C. Jan 30, 2018. For reasons that now escape me, I stopped using strtok to parse strings in C. I can only guess that it was  Here, a begins life as the compound string "A-B-C", after the code executes, there are three null-terminated strings, a, b, and c which have the values "A", "B" and "C". The <handle error> is a place-holder for code to react to missing delimiters. Note that, like strtok, the original string is modified by replacing the delimiters with NULLs.


Splitting a string using strtok() in C, In C, the strtok() function is used to split a string into a series of tokens based on a particular delimiter. A token is a substring extracted from the original string. I'm looking for a simple way to tokenize string input without using non default libraries such as Boost, etc. For example, if the user enters forty_five, I would like to seperate forty and five using the _ as the delimiter.


STR06-C. Do not assume that strtok() leaves the parse string , The C function strtok() is a string tokenization function that takes two arguments: an initial string to be parsed and a const -qualified character delimiter. It returns  In this section, we will see how to tokenize strings in C++. In C we can use the strtok() function for the character array. Here we have a string class. Now we will see how to cut the string using some delimiter from that string. To use the C++ feature, we have to convert a string to a string stream. Then using getline() function we can do the


Tokenize a string, Works with: C++98. std::getline() is typically used to tokenize strings on a single-​character delimiter #include <string> #include <sstream> 2. Java split string – String.split() String.split() method is better and recommended than using StringTokenizer. Here tokens are returned in form of a string array which we are free to use as we wish. Program to split a string in java with delimiter comma.