c/c++课的作业合集,都是很简单的文件。
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//
// Created by lenfrex on 2022/4/4.
//
#include <cstring>
#include <algorithm>
#include "CString.h"
/**
*
*/
CString::CString(int size) : length(0), allocSize(size) {
data = new char[size]();
}
/**
* 512
*/
CString::CString() : CString(512) {}
/**
*
*/
CString::CString(char *source) : CString(source, (int) strlen(source)) {}
/**
*
*/
CString::CString(char *source, int length) : CString(length + 1) {
strncpy(data, source, length);
data[length] = '\0';
this->length = length;
}
CString::~CString() {
delete[] data;
data = nullptr;
}
CString::CString(const CString &source) : CString(source.data) {}
/**
* Java中String类的equal()
* data是否为nullptrnull则truefalse
* false
* true
*
*/
bool CString::operator==(const CString &source) const {
// 首先判断两CString对象data成员是否为空指针
if (source.data == nullptr || this->data == nullptr) {
return source.data == nullptr && this->data == nullptr;
}
// 字符串长度不等,字符串肯定是不等
if (length != source.length) {
return false;
} else {
// 长度相等且data指向相同肯定等
if (source.data == this->data) {
return true;
}
}
// 以上情况都不符合时才进行逐字比较
// 能执行到此处两者长度肯定相等,因此访问数组不会越界
for (int i = 0; i < length; ++i) {
if (data[i] != source.data[i]) {
return false;
}
}
return true;
}
CString &CString::operator=(const CString &source) {
// 处理自己给自己赋值的情况,那叫啥,自赋值
if (this == &source) {
return *this;
}
// 等号右侧空指针的话直接data赋为空指针
if (source.data == nullptr) {
delete[] data;
this->data = nullptr;
length = 0;
allocSize = 0;
return *this;
}
int sourceLength = (int) strlen(source.data);
// 如果源字符串长度超过了本对象已分配的字符数组大小则重新分配长度合适的字符数组
if (allocSize < sourceLength) {
allocSize = sourceLength + 1;
delete[] data;
data = new char[allocSize];
}
strcpy(data, source.data);
length = sourceLength;
return *this;
}
CString &CString::operator+=(const CString &source) {
// nullptr不做处理
if (source.data == nullptr) {
return *this;
}
// 本对象nullptr的话就直接新分配
if (data == nullptr) {
allocSize = source.length + 2 + 1;
this->data = new char[allocSize]();
length = source.length;
} else {
length = (int) strlen(data);
}
// 如果拼接后字符长度超过已分配的内存大小,则重新分配data内存大小
if (allocSize < (length + source.length + 2)) {
// 保存拼接前的原数据,以便重新分配足够的内存
char *old = new char[length + 1]();
strcpy(old, data);
// 重新分配内存,防止拼接后溢出,2为两个横杠大小
length += source.length + 2;
allocSize = length + 1;
delete[] data;
this->data = new char[allocSize]();
strcpy(data, old);
}
strcat(data, "--");
strcat(data, source.data);
return *this;
}
/**
*
*/
bool CString::operator>(const CString &compareString) const {
// 首先判断两CString对象data成员是否为空指针,空直接返回false
if (compareString.data == nullptr || this->data == nullptr) {
return false;
}
// 两对象data成员首指向相同则对比谁长
if (compareString.data == this->data) {
return length > compareString.length;
}
// 以上情况都不符合时才进行比较
return strcoll(this->data, compareString.data) > 0;
}
std::ostream &operator<<(std::ostream &outputStream, const CString &source) {
return outputStream << source.data;
}
std::istream &operator>>(std::istream &inputStream, CString &source) {
// 使用istream.get(char*, int)可以限制读入的长度,防止输入超长的字符串导致溢出,但是空格也会被读入
// 手动分割太麻烦,因此只好先用这种方法了
inputStream >> source.data;
source.length = (int) strlen(source.data);
return inputStream;
}
char CString::operator[](int i) {
return (i < length && i >= 0) ? data[i] : '\0';
}