C++ 字符串处理2-去除字符串前后的空字符

#include <string>
namespace cutl
{
    /**
     * @brief Remove leading whitespaces from a string.
     *
     * @param str the string to be stripped.
     * @return std::string the stripped string.
     */
    std::string lstrip(const std::string &str);
    /**
     * @brief Remove trailing whitespaces from a string.
     *
     * @param str the string to be stripped.
     * @return std::string the stripped string.
     */
    std::string rstrip(const std::string &str);
    /**
     * @brief Remove leading and trailing whitespaces from a string.
     *
     * @param str the string to be stripped.
     * @return std::string the stripped string.
     */
    std::string strip(const std::string &str);
} // namespace cutl

#include <cctype>
#include <algorithm>
#include "strutil.h"

namespace cutl
{
    std::string lstrip(const std::string &str)
    {
        if (str.empty())
        {
            return "";
        }

        size_t index = 0;
        for (size_t i = 0; i < str.length(); i++)
        {
            if (!std::isspace(str[i]))
            {
                index = i;
                break;
            }
        }

        return str.substr(index, str.length() - index);
    }

    std::string rstrip(const std::string &str)
    {
        if (str.empty())
        {
            return "";
        }

        size_t index = str.length() - 1;
        for (size_t i = str.length() - 1; i >= 0; i--)
        {
            if (!std::isspace(str[i]))
            {
                index = i;
                break;
            }
        }
        return str.substr(0, index + 1);
    }

    std::string strip(const std::string &str)
    {
        if (str.empty())
        {
            return "";
        }

        size_t index1 = 0;
        for (size_t i = 0; i < str.length(); i++)
        {
            if (!std::isspace(str[i]))
            {
                index1 = i;
                break;
            }
        }
        size_t index2 = str.length() - 1;
        for (size_t i = str.length() - 1; i >= 0; i--)
        {
            if (!std::isspace(str[i]))
            {
                index2 = i;
                break;
            }
        }
        auto len = index2 - index1 + 1;

        return str.substr(index1, len);
    }
} // namespace cutl

#include "common.hpp"
#include "strutil.h"

void TestStrip()
{
    PrintSubTitle("TestStrip");

    std::string text = "  \tThis is a test string. \n ";
    // std::string text = "  \t中国 \n ";
    std::cout << "text: " << text << std::endl;
    std::cout << "trim left text: " << cutl::lstrip(text) << std::endl;
    std::cout << "trim right text: " << cutl::rstrip(text) << std::endl;
    std::cout << "trim text: " << cutl::strip(text) << std::endl;
}