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＜C++学习＞ C++ Boost 字符串操作教程

article 2025/1/15 6:09:36

C++ Boost 字符串操作教程

Boost 提供了一些实用的库来增强 C++ 的字符串操作能力，特别是 Boost.StringAlgo 和其他与字符串相关的工具。这些库为字符串处理提供了更高效、更简洁的方法，相比标准库功能更为丰富。

1. Boost.StringAlgo 简介

Boost.StringAlgo 是 Boost 提供的字符串处理库，包含了多种字符串操作的工具，例如：

查找与替换。
字符串拆分与合并。
转换大小写。
修剪字符串（去掉首尾的空白字符）。
检查与比较。

头文件：

#include <boost/algorithm/string.hpp>

命名空间：

namespace ba = boost::algorithm;

2. 字符串操作的主要功能

2.1 转换大小写

示例：转为小写

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

int main() {
    std::string str = "HeLLo WoRLd!";
    boost::algorithm::to_lower(str); // 转为小写
    std::cout << "Lowercase: " << str << std::endl;

    return 0;
}

示例：转为大写

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

int main() {
    std::string str = "HeLLo WoRLd!";
    boost::algorithm::to_upper(str); // 转为大写
    std::cout << "Uppercase: " << str << std::endl;

    return 0;
}

2.2 修剪字符串

修剪首尾的空白字符或指定字符。

示例：修剪空白

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

int main() {
    std::string str = "   Hello World!   ";
    boost::algorithm::trim(str); // 修剪空白
    std::cout << "Trimmed: '" << str << "'" << std::endl;

    return 0;
}

示例：修剪特定字符

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

int main() {
    std::string str = "---Hello World!---";
    boost::algorithm::trim_if(str, boost::is_any_of("-")); // 修剪 '-'
    std::cout << "Trimmed: '" << str << "'" << std::endl;

    return 0;
}

2.3 字符串拆分

将字符串按指定分隔符拆分为多个部分。

示例：按空格拆分

#include <boost/algorithm/string.hpp>
#include <iostream>
#include <vector>
#include <string>

int main() {
    std::string str = "Boost is powerful";
    std::vector<std::string> parts;

    boost::algorithm::split(parts, str, boost::is_space()); // 按空格拆分

    for (const auto& part : parts) {
        std::cout << part << std::endl;
    }

    return 0;
}

示例：按逗号拆分

#include <boost/algorithm/string.hpp>
#include <iostream>
#include <vector>
#include <string>

int main() {
    std::string str = "Boost,C++,Library";
    std::vector<std::string> parts;

    boost::algorithm::split(parts, str, boost::is_any_of(",")); // 按 ',' 拆分

    for (const auto& part : parts) {
        std::cout << part << std::endl;
    }

    return 0;
}

2.4 字符串合并

将字符串集合合并为一个字符串。

示例：合并字符串

#include <boost/algorithm/string.hpp>
#include <iostream>
#include <vector>
#include <string>

int main() {
    std::vector<std::string> parts = {"Boost", "is", "awesome"};

    std::string result = boost::algorithm::join(parts, " "); // 用空格合并
    std::cout << "Joined: " << result << std::endl;

    return 0;
}

2.5 查找与替换

示例：查找子字符串

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

int main() {
    std::string str = "Boost is powerful";

    if (boost::algorithm::contains(str, "powerful")) {
        std::cout << "'powerful' is found in the string!" << std::endl;
    }

    return 0;
}

示例：替换子字符串

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

int main() {
    std::string str = "Boost is powerful";
    boost::algorithm::replace_all(str, "powerful", "amazing"); // 替换所有匹配的子字符串
    std::cout << "Replaced: " << str << std::endl;

    return 0;
}

2.6 比较字符串

示例：忽略大小写比较

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

int main() {
    std::string str1 = "Boost";
    std::string str2 = "boost";

    if (boost::algorithm::iequals(str1, str2)) {
        std::cout << "The strings are equal (case-insensitive)." << std::endl;
    }

    return 0;
}

2.7 字符串判断

示例：判断前缀和后缀

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

int main() {
    std::string str = "Boost Library";

    if (boost::algorithm::starts_with(str, "Boost")) {
        std::cout << "The string starts with 'Boost'." << std::endl;
    }

    if (boost::algorithm::ends_with(str, "Library")) {
        std::cout << "The string ends with 'Library'." << std::endl;
    }

    return 0;
}

2.8 字符串反转

示例：反转字符串

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

int main() {
    std::string str = "Boost";
    boost::algorithm::reverse(str); // 反转字符串
    std::cout << "Reversed: " << str << std::endl;

    return 0;
}

3. 综合示例

以下示例展示了 Boost.StringAlgo 的多个功能结合使用。

完整代码

#include <boost/algorithm/string.hpp>
#include <iostream>
#include <vector>
#include <string>

int main() {
    std::string str = "  Boost is powerful, Boost is awesome  ";

    // 修剪空白
    boost::algorithm::trim(str);
    std::cout << "Trimmed: '" << str << "'" << std::endl;

    // 转换大小写
    boost::algorithm::to_upper(str);
    std::cout << "Uppercase: " << str << std::endl;

    // 拆分字符串
    std::vector<std::string> parts;
    boost::algorithm::split(parts, str, boost::is_any_of(","));
    for (const auto& part : parts) {
        std::cout << "Part: '" << part << "'" << std::endl;
    }

    // 合并字符串
    std::string joined = boost::algorithm::join(parts, " | ");
    std::cout << "Joined: " << joined << std::endl;

    return 0;
}