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1.写文件
ofstream outfile("file_name",open_mode);
打开模式可以缺省，此时默认每次都是擦除文件中的原始数据，然后再写入此次的内容；
追加内容采用：ios_base::app
ofstream outfile("out_file.txt",ios_base::app); if (!outfile) cerr << "Oops! Unable to save data!" << endl; else outfile << "username" << ‘ ‘ << 18<< ‘ ‘ << 18<< endl;
2.读文件
ifstream infile("file_name",open_mode);
ifstream infile("out_file.txt"); string user_name; int nc_all; int nc_rgt; while (infile >> user_name) { infile >> nc_all >> nc_rgt; if (user_name == "username") { cout << "Welcome " << user_name << " back!" << endl; cout << "Your current score is " << nc_rgt << " out of " << nc_all << " " << endl; cout << "Good Luck!" << endl; } }
3.读写同一个文件
fstream iofile("file_name",open_mode_1|open_mode_2);
对同一个文件进行读写，要特别注意当文件为添加模式时，文件流指针位于文件末尾，要及时修改文件流指针的位置（seekg()函数）
fstream iofile("test.txt",ios_base::app|ios_base::in); if (!iofile) cerr << "Oops! Unable to open the file!" << endl; else { cout << "Success!" << endl; iofile << "test" << ‘ ‘ << "100" << ‘ ‘ << "100" << endl; iofile.seekg(ios::beg); string user_name; string right; string all; while (iofile >> user_name) { iofile >> right >> all; cout << "Your name is " << user_name << endl; cout << "Your score is " << right << " out of " << all << endl; } }
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原文地址：http://www.cnblogs.com/acode/p/4494278.html
