【C++指南】string（二）：深入探究 C++ `basic_string`：成员变量、函数全解析

template <typename CharT, typename Traits = std::char_traits<CharT>, typename Allocator = std::allocator<CharT>>
class basic_string {
private:
    CharT* _data;  // 字符存储指针
    size_t _size;  // 字符串长度
    size_t _capacity;  // 容量
    // 其他可能的成员变量和实现细节
};

#include <iostream>
#include <string>

int main() {
    std::string str;  // 默认构造，创建空字符串
    std::cout << "Empty string: " << str << std::endl;
    return 0;
}

std::string str("Hello, World!");
std::cout << "Initialized with literal: " << str << std::endl;

std::string str(5, 'a');  // 初始化为 "aaaaa"
std::cout << "Repeated characters: " << str << std::endl;

std::string original("Original");
std::string copy(original);
std::cout << "Copied string: " << copy << std::endl;

{
    std::string str("Temporary");
    // 当 str 离开作用域时，析构函数自动调用
}

std::string source("Source");
std::string destination;
destination = source;
std::cout << "Assigned string: " << destination << std::endl;

std::string str("Iterate");
for (auto it = str.begin(); it != str.end(); ++it) {
    std::cout << *it << " ";
}
std::cout << std::endl;

for (auto rit = str.rbegin(); rit != str.rend(); ++rit) {
    std::cout << *rit << " ";
}
std::cout << std::endl;

const std::string constStr("Constant");
for (auto cit = constStr.cbegin(); cit != constStr.cend(); ++cit) {
    std::cout << *cit << " ";
}
std::cout << std::endl;

std::string str("Capacity");
std::cout << "Size: " << str.size() << ", Length: " << str.length() << std::endl;

std::cout << "Capacity: " << str.capacity() << std::endl;

str.reserve(20);
std::cout << "Reserved capacity: " << str.capacity() << std::endl;

str.resize(3);
std::cout << "Resized string: " << str << std::endl;
str.resize(5, 'x');
std::cout << "Resized and filled: " << str << std::endl;

std::string str("Insert");
str.insert(2, "abc");  // 在位置 2 插入 "abc"
std::cout << "Inserted string: " << str << std::endl;

str.erase(2, 3);  // 从位置 2 开始删除 3 个字符
std::cout << "Erased string: " << str << std::endl;

str.push_back('!');
std::cout << "Pushed back: " << str << std::endl;

str.append(" World");
std::cout << "Appended string: " << str << std::endl;
str += "!";
std::cout << "Appended with +=: " << str << std::endl;

std::string str("Find me");
size_t pos = str.find("me");
if (pos != std::string::npos) {
    std::cout << "Found at position: " << pos << std::endl;
} else {
    std::cout << "Not found" << std::endl;
}

str.replace(0, 4, "Replace");
std::cout << "Replaced string: " << str << std::endl;

std::string str1("Hello");
std::string str2("World");
int result = str1.compare(str2);
if (result < 0) {
    std::cout << str1 << " is less than " << str2 << std::endl;
} else if (result > 0) {
    std::cout << str1 << " is greater than " << str2 << std::endl;
} else {
    std::cout << str1 << " is equal to " << str2 << std::endl;
}