[SOLVED] How do I tokenize a string in C++?


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) {

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},

Answered By – Konrad Rudolph

Answer Checked By – Willingham (BugsFixing Volunteer)

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