对个人真的自学程式设计最有效率的形式是写作专精的书刊，透过写作工具书能构筑更为管理体系化的科学知识管理体系。 始终年来都很想深入细致自学呵呵C++，将其做为他们的主力部队合作开发词汇。那时为的是顺利完成他们这始终年来的愿望，预备认真自学《C++ Primer Plus》。 为的是提升自学工作效率，在自学的桑利县透过正式发布自学讲义的形式，稳步历史记录他们自学C++的操作过程。
// outfile.cpp — writing to a file#include <iostream>#include <fstream> // for file I/Oint main(){ using namespace std; char automobile[50]; int year; double a_price; double d_price; ofstream outFile; // create object for output outFile.open(“e:\\1.txt”); // associate with a file cout << “Enter the make and model of automobile: “; cin.getline(automobile, 50); cout << “Enter the model year: “; cin >> year; cout << “Enter the original asking price: “; cin >> a_price; d_price = 0.913 * a_price;// display information on screen with cout cout << fixed;//按浮点型进行输出。 cout.precision(2);//控制浮点精度为2，即保留小数点位数 cout.setf(ios_base::showpoint);//采用默认的浮点文件格式时,上述句子还将导致末尾的0被显示出来。 cout << “Make and model: ” << automobile << endl; cout << “Year: ” << year << endl; cout << “Was asking $” << a_price << endl; cout << “Now asking $” << d_price << endl;// now do exact same things using outFile instead of cout outFile << fixed; outFile.precision(2); outFile.setf(ios_base::showpoint); outFile << “Make and model: ” << automobile << endl; outFile << “Year: ” << year << endl; outFile << “Was asking $” << a_price << endl; outFile << “Now asking $” << d_price << endl; outFile.close(); // done with file // cin.get(); // cin.get(); return 0;}
读取文件使用ifstream：
// sumafile.cpp — functions with an array argument#include <iostream>#include <fstream> // file I/O support#include <cstdlib> // support for exit()const int SIZE = 60;int main(){ using namespace std; char filename[SIZE]; ifstream inFile; // object for handling file input cout << “Enter name of data file: “; cin.getline(filename, SIZE); inFile.open(filename); // associate inFile with a file if (!inFile.is_open()) // failed to open file { cout << “Could not open the file ” << filename << endl; cout << “Program terminating.\n”; // cin.get(); // keep window open exit(EXIT_FAILURE); } double value; double sum = 0.0; int count = 0; // number of items read inFile >> value; // get first value while (inFile.good()) // while input good and not at EOF { ++count; // one more item read sum += value; // calculate running total inFile >> value; // get next value } if (inFile.eof()) cout << “End of file reached.\n”; else if (inFile.fail()) cout << “Input terminated by data mismatch.\n”; else cout << “Input terminated for unknown reason.\n”; if (count == 0) cout << “No data processed.\n”; else { cout << “Items read: ” << count << endl; cout << “Sum: ” << sum << endl; cout << “Average: ” << sum / count << endl; } inFile.close(); // finished with the file // cin.get(); return 0;}
