标签：return 封装 hello buffer using stream ESS https col
每一次切换文件操作模式必须调用fclose关闭文件。
如果直接切换操作模式，文件将损坏（出现乱码）或操作失败。
在调用了fclose时，作为参数的文件指针将被回收，必须再次定义，因此最好将功能封装。
存数组时，fwrite参数size_t size可使用sizeof(buffer[0])，size_t count可使用sizeof(buffer)/sizeof(buffer[0])。
fread返回了一个整数，是其成功读取的数据数目，最大值是其参数size_t count。
使用循环顺序读取时while(!feof(stream))，fread在一次读取不完整后触发文件尾条件。
#include<iostream> #include<fstream> int main() { using std::cin; using std::cout; using std::endl; cout << "Hello, I am a C++ test program." << endl; cin.get(); //++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ FILE* _f0; _f0 = fopen("f0.txt", "wb"); if (_f0 != NULL) { cout << "I created a file named \"f0\"." << endl; cin.get(); int buf[8]; cout << "size of buf[0] = " << sizeof(buf[0]) << endl << "size of buf = " << sizeof(buf) << endl; for (int i = 0; i < 8; i++) { buf[i] = ‘0‘ + i; } fwrite(buf, sizeof(buf[0]), sizeof(buf)/sizeof(buf[0]), _f0); cout << "Then put some numbers into this file." << endl; cin.get(); cout << "Read out these numbers:" << endl; fclose(_f0); FILE* _f1 = fopen("f0.txt", "rb"); cout << "f0 = " << _f1 << endl; int i = 0; int R = 0; int n = 0; while (!feof(_f1)) { n = fread(&R, sizeof(R), 1, _f1); cout << "n = " << n << " buf[" << i << "] = " << R << endl; i++; } fclose(_f1); cout << "At last, add a number to the file." << endl; FILE* _f2 = fopen("f0.txt", "ab"); R = ‘8‘; fwrite(&R, sizeof(R), 1, _f2); fclose(_f2); } else { cout << "File creating failed." << endl; } //++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ cout << endl << "Press enter to end."; cin.get(); return 0; }
标签：return 封装 hello buffer using stream ESS https col
原文地址：https://www.cnblogs.com/eternalmoonbeam/p/11617114.html
