C++: improved string tokenizer

Using templates the old string tokenzier can be further improved:

template  void tokenize(const std::string &str,
              T &tokens,
              const std::string &delimiters = " ") {
  string::size_type lastPos = str.find_first_not_of(delimiters, 0);
  string::size_type pos = str.find_first_of(delimiters, lastPos);

  while (std::string::npos != pos || std::string::npos != lastPos) {
    tokens.push_back(str.substr(lastPos, pos - lastPos));
    lastPos = str.find_first_not_of(delimiters, pos);
    pos = str.find_first_of(delimiters, lastPos);
  }
}

This allows any container with a push_back() method to receive the extracted tokens.

std::list tokens;
tokenize("I want to tokenize this!", tokens);

tokenize("2012-02-20", tokens, "-");

or

std::vector tokens;
tokenize("I want to tokenize this!", tokens);

tokenize("2012-02-20", tokens, "-");

C++: String startsWith function

This function checks if the supplied string starts with the specified prefix.

bool string_startsWith(const std::string &str, const std::string &prefix) {
  return std::equal(prefix.begin(), prefix.end(), str.begin());
}

C++: string tokenzier

This function splits a string into substrings. It uses a list of delimiter characters to find the boundaries of the substrings.

void tokenize(const std::string &str, 
              std::vector<std::string> &tokens, 
              const std::string &delimiters = " ") {
  string::size_type lastPos = str.find_first_not_of(delimiters, 0);
  string::size_type pos = str.find_first_of(delimiters, lastPos);

  while (std::string::npos != pos || std::string::npos != lastPos) {
    tokens.push_back(str.substr(lastPos, pos - lastPos));
    lastPos = str.find_first_not_of(delimiters, pos);
    pos = str.find_first_of(delimiters, lastPos);
  }
}

Usage:

vector<std::string> tokens;
tokenize("I want to tokenize this!", tokens);

tokenize("2012-02-20", tokens, "-");

C++: String trim function

This function removes leading and trailing characters from a string. The default character is a space, but you can use any combination of characters, that should be trimmed.

std::string trim(std::string &str, const std::string &trimChars = " ")
{
  std::string result = str.erase(str.find_last_not_of(trimChars) + 1);
  return result.erase(0, result.find_first_not_of(trimChars));
}

Usage:

string s = trim("Hello World!    ");
std::cout << s;
// prints: Hello World!

s = trim("xxx Hello World! xxx", "x");
std::cout << s;
// prints: Hello World!