c 异常和文件操作

代码在AS上运行的

异常

四种异常抛出方法

#include <iostream>
#include <string>
#include "mylog.h"
#include "main_03.h"
using namespace std;
//异常测试
void exceptionMethod01() {
    throw "我抛出了异常";
}
//异常测试2
void exceptionMethod02() {
    throw exception();
}
//异常测试3 --自定义异常
class CustomException : public exception {
public:
    const char *what() const noexcept override {
        return "我要抛出自定义异常了";
    }
};
void exceptionMethod03() {
    throw CustomException();
}
//异常测试4 自定义异常
class Student {
public:
    char *getInfo(){
        return "自定义异常4";
    }
};
void exceptionMethod04(){
    Student s;
    throw s;
}
void main_03() {
    try {
        exceptionMethod01();
    } catch (const char *errMsg) {
        LOG("捕获到了异常信息：%s", errMsg);
    }
    try {
        exceptionMethod02();
    } catch (exception &errMsg) {
        LOG("捕获到了异常信息：%s", errMsg.what());
    }
    try {
        exceptionMethod03();
    } catch (CustomException &errMsg) {
        LOG("捕获到了异常信息：%s", errMsg.what());
    }
    try {
        exceptionMethod04();
    } catch (Student &errMsg) {
        LOG("捕获到了异常信息：%s", errMsg.getInfo());
    }
}

IO流

IO缓冲区

cin.ignore(numeric_limits::max(), ‘\n’); //清空缓冲区脏数据

文件操作

文件操作步骤

文件打开方式

文本文件的操作

    char a;
    int index = 0;
    fstream fout;
    fout.open("testBuffer.txt", ios::app);
    if(fout.fail()){
        cout << "The file open fail" << endl;
    }
    while (cin >> a) {
//        cout << "in while：" << a << endl;
        fout << "in while: " << a << endl;
        index++;
        if (index == 5) {
            break;
        }
    }
    cin.ignore(numeric_limits<streamsize>::max(), '\n');  //清空缓冲区脏数据
    char ch;
    cin >> ch;
//    cout << "out while：" << ch << endl;
    fout << "out while：" << ch << endl;
    fout.close();

二进制文件的操作

#include <fstream>
bool CopyFile(const string& str, const string& dst){
    ifstream in(str.c_str(), std::ios::in | std::ios::binary);
    ofstream out(dst.c_str(), std::ios::out | std::ios::binary | std::ios::trunc);
    if(!in || !out){
        return false;
    }
    char temp[bufferLen];
    while (!in.eof()){
        in.read(temp, bufferLen);
        streamsize  count = in.gcount();
        out.write(temp, count);
    }
    in.close();
    out.close();
    return true;
}