Exception Handling

標題：例外處理的方法
VC++ (main.cpp)：

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#include "stdafx.h" #include <iostream> #include <regex> #include <fstream> using namespace std; class pos { public: float x; float y; float z; }; class ERR { private: int kind; public: ERR(int k) : kind(k){}; //建構函式 char* message() { switch(kind) { case 0: return "Error A"; case 1: return "Error B"; case 2: return "Error C"; } } }; void readfile(string path) { string lines = ""; ifstream File(path); if (File.is_open()) //Check File { while(File.good()) { getline(File, lines); cout << lines << endl; } File.close(); } } int main(int argc, char *argv[]) { switch(0) //Select Example { case 0: { //Example 1 int n = 0; string str = "Hello"; try { cin >> n; cout << str.at(n) << endl; //取得字串的第n個字元 } catch (...) { cout << "Error!" << endl; } break; } case 1: { //Example 2 float num = 1; try { cout << "num="; cin >> num; if(num == 0) { throw "Infinity!"; } cout << "100/num=" << 100/num << endl; } catch (const char* message) { cout << message << endl; } break; } case 2: { //Example 3 try { if(argc<2) { throw "Parameter error."; } char pathChar[1024]; regex pathRegex("([a-zA-Z]\:\\\\(?:[^\\\\]+\\\\)*.*)"); //"C:\\temp\\hello.txt" cmatch pathMatch; //cmatch: Char Match strcpy(pathChar, argv[1]); //Pointer to Char if(regex_match(pathChar, pathMatch, pathRegex)) //char, cmatch, regexp { readfile(pathMatch[1].str()); } else { throw "Path Error."; } } catch(const char* message) { cout << message << endl; } break; } case 3: { //Example 4 pos p; p.x = 1.1f; p.y = 2.2f; p.z = 3.3f; cout << "(" << p.x << ", " << p.y << ", " << p.z << ")" << endl; break; } case 4: { //Example 5 try { throw ERR(0); } catch(ERR e) { cout << e.message() << endl; } break; } } system("pause"); return 0; }

說明：
一般及搭配argc、argv、Regular Expression、Class例外處理的方法