C++ Whitespace Trimming Functions

Some simple functions for removing leading or trailing whitespace from strings in C++. It uses isspace() and your current locale (by default) to determine what is considered whitespace (e.g., space, tab, newline, etc.) and modifies the strings in-place.

The header file, btrim.hpp:

#ifndef BTRIM_HPP
#define BTRIM_HPP

#include <string>
#include <locale>

/** 
 * Strip leading whitespace from a string.
 *
 * @param[in] str Reference to the string to be trimmed. Modified in-place.
 * @param[in] loc Locale to use (optional).
 * @return        void
 */
void ltrim(std::string& str, const std::locale& loc = std::locale());

/**
 * Strip trailing whitespace from a string.
 *
 * @param[in] str Reference to the string to be trimmed. Modified in-place.
 * @param[in] loc Locale to use (optional).
 * @return        void
 */
void rtrim(std::string& str, const std::locale& loc = std::locale());

/**
 * Strip both leading and trailing whitespace from a string.
 *
 * @param[in] str Reference to the string to be trimmed. Modified in-place.
 * @param[in] loc Locale to use (optional).
 * @return        void
 */
void btrim(std::string& str, const std::locale& loc = std::locale());

#endif // BTRIM_HPP

The implementation file, btrim.cpp:

#include "btrim.hpp"

using namespace std;

void ltrim(string& str, const locale& loc) {
  string::size_type pos = 0;
  while (pos < str.size() && isspace(str[pos], loc)) pos++;
  str.erase(0, pos);
}

void rtrim(string& str, const locale& loc) {
  string::size_type pos = str.size();
  while (pos > 0 && isspace(str[pos - 1], loc)) pos--;
  str.erase(pos);
}

void btrim(string& str, const locale& loc) {
  ltrim(str, loc);
  rtrim(str, loc);
}

Example usage:

// Example use of trim whitespace functions
#include <string>
#include <iostream>
#include "btrim.hpp"

using namespace std;

int main () {
  string s = "   zort   ";
  btrim(s); /* trim spaces, both leading and trailing */
  cout << "Trimmed string: |" << s << "|" << endl;
}