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125 lines
3.1 KiB
125 lines
3.1 KiB
//
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// Created by lenfrex on 2022/4/4.
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//
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#include <cstring>
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#include <algorithm>
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#include "CString.h"
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/*
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* 按照给定大小来初始化字符串数据
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*/
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CString::CString(int length) {
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data = new char[length]();
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CString::length = length;
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}
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CString::~CString() {
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delete[] data;
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}
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/*
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* 不设定初始化大小就默认512个字符来初始化
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*/
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CString::CString() : CString(512) {}
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/*
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* 重载等号。借鉴了Java中String类的equal()方法的实现。
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* 首先比较两字符串长度，如果长度不一样不用说，直接返回false；如果data为nullptr，不做比较并返回false
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* 相同的话再比较两字符串数据指针指向地址是否一样，一样就代表指向的是同一块内存，直接返回true
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* 两者都不同才进行逐字比较
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*/
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bool CString::operator==(const CString &source) const {
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// 判断两CString长度以及本对象data成员是否为空指针
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if (source.length != length || data == nullptr) {
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return false;
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} else {
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// 判断两对象data成员是否指向同一内存块
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if (source.data == data) {
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return true;
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}
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}
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// 以上情况都不符合时才进行逐字比较
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int compareLength = std::min(source.length, length);
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for (int i = 0; i < compareLength; ++i) {
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if (data[i] != source.data[i]) {
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return false;
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}
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}
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return true;
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}
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/*
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* 从源中复制字符串来构建新的对象
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*/
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CString::CString(char *source) : CString((int)strlen(source)) {
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strncpy(data, source, length);
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}
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/*
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* 从源中复制字符串来构建新的对象，并定义初始长度，小于源字符串则会被截取
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*/
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CString::CString(char *source, int length) : CString(length) {
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strncpy(data, source, length);
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}
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CString &CString::operator=(const CString &source) {
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// 处理自己给自己赋值的情况，那叫啥，自赋值
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if (this == &source) {
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return *this;
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}
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if (data != nullptr && length != 0) {
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delete[] data;
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}
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this->length = source.length;
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this->data = new char[length]();
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strncpy(data, source.data, length);
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return *this;
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}
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CString &CString::operator+=(const CString &source) {
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if (data == nullptr && length == 0) {
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this->length = source.length;
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this->data = new char[length]();
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}
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char *tmp = new char[length]();
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strncpy(tmp, data, length);
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// 重新分配内存，防止拼接后溢出
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delete[] data;
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this->length += source.length;
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this->data = new char[this->length];
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strcpy(tmp, data);
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strncat(data, source.data, source.length);
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return *this;
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}
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CString::CString(const CString &source) : CString(source.data, source.length) {}
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/*
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* 按照字典顺序逐字对比
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*/
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bool CString::operator<(const CString &source) const {
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// 这部分类似于前边==重载的前置判断，如果本对象数据为null或者两对象数据是一回事就直接false
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if (data == nullptr || (source.length != length && source.data == data)) {
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return false;
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}
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// 以上情况都不符合时才进行逐字比较
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int compareLength = std::min(source.length, length);
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for (int i = 0; i < compareLength; ++i) {
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if (data[i] < source.data[i]) {
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return true;
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}
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}
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return false;
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}
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