C++ 練手

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// namespace.cpp : 定義控制台應用程式的進入點。//#include "stdafx.h"#include <iostream>#include <cstdlib>namespace MyLib {double readAndProcessSum (std::istream&);}int _tmain(int argc, _TCHAR* argv[]){using namespace std;double sum;try {sum = MyLib::readAndProcessSum(cin);}catch (const ios::failure& error) {cerr << "I/O exception: " << error.what() << endl;return EXIT_FAILURE;}catch (const exception& error) {cerr << "standard exception: " << error.what() << endl;return EXIT_FAILURE;}catch (...) {cerr << "unknown exception" << endl;return EXIT_FAILURE;}// print sumcout << "sum: " << sum << endl;}#include <istream>namespace MyLib {double readAndProcessSum (std::istream& strm){using std::ios;double value, sum;// save current state of exception flagsios::iostate oldExceptions = strm.exceptions();/* let failbit and badbit throw exceptions* - NOTE: failbit is also set at end-of-file*/strm.exceptions (ios::failbit | ios::badbit);try {/* while stream is OK* - read value and add it to sum*/sum = 0;while (strm >> value) {sum += value;}}catch (...) {/* if exception not caused by end-of-file* - restore old state of exception flags* - rethrow exception*/if (!strm.eof()) {strm.exceptions(oldExceptions);  // restore exception flagsthrow;                           // rethrow}}// restore old state of exception flagsstrm.exceptions (oldExceptions);// return sumreturn sum;}}

 

C++ 練手