C++读书笔记之 文件与流 文件读写操作 通过指针获取文件大小
在本例程中不仅概括了文件的基本读写操作，如何获取文件的大小，还牵扯到getline和cin.getline的区别，及string类字符串如何转换为c风格字符串的问题，这些问题将在下一篇博文中介绍。首先先看程序运行结果，运行结果如下：
/**********************************
程序运行结果如下：
Writing to the file
Enter your name: wangshihui
Enter your age: 22
Reading from the file
wangshihui
22
wangshihui
22
To recap, the three main objectives in the Mystery Method are:
To attract a woman
To establish comfort, trust, and connection
To structure the opportunity to be seduced
A woman's number-one emotional priority is safety and security.
TheMisteryMethod.txt size is: 294 bytes.
Process returned 0 (0x0) execution time : 13.100 s
Press any key to continue.
***********************************/
[cpp]
#include <fstream>
#include <iostream>
using namespace std;
void test_write_read_cin_getline()
{
char data[100];
// open a file in write mode.
ofstream outfile;
outfile.open("TheMisteryMethod.txt");
cout << "Writing to the file" << endl;
cout << "Enter your name: ";
cin.getline(data, 100);
// write inputted data into the file.
outfile << data << endl;
cout << "Enter your age: ";
cin >> data;
cin.ignore();
// again write inputted data into the file.
outfile << data << endl;
// close the opened file.
outfile.close();
// open a file in read mode.
ifstream infile;
infile.open("TheMisteryMethod.txt");
cout << "Reading from the file" << endl;
infile >> data;
// write the data at the screen.
cout << data << endl;
// again read the data from the file and display it.
infile >> data;
cout << data << endl;
// close the opened file.
infile.close();
}
void test_write()
{
ofstream myfile;
myfile.open ("TheMisteryMethod.txt",ios::app);
if(myfile.is_open())
{
myfile <<
"\nTo recap, the three main objectives in the Mystery Method are: \n\
To attract a woman \n\
To establish comfort, trust, and connection \n\
To structure the opportunity to be seduced \n";
myfile.close();
}
else
cout<<"打开文件失败！\n";
}
void test_write_read_getline()
{
string str;
//Creates an instance of ofstream, and opens TheMisteryMethod.txt
ofstream a_file ( "TheMisteryMethod.txt",ios::app );//追加方式
// Outputs to TheMisteryMethod.txt through a_file
if(a_file.is_open())
{
a_file<<"A woman's number-one emotional priority is safety and security.";
// Close the file stream explicitly
a_file.close();
}
else
cout << "Unable to open file\n";
//Opens for reading the file 追加方式
ifstream b_file ( "TheMisteryMethod.txt",ios::app );
//Reads one string from the file
b_file>> str; //只显示to 表示遇到空格停止接收字符
cout<< str <<"\n";
getline(b_file,str,'\0');//输出缓冲区剩余的字符
cout<< str <<"\n";
cin.get(); // wait for a keypress
// b_file is closed implicitly here
}
void GetSizeOfFile(string filename)
{
long begin,end;
ifstream myfile (filename.c_str());//必须转换为c风格字符串
begin = myfile.tellg();
myfile.seekg (0, ios::end);
end = myfile.tellg();
myfile.close();
cout <<filename<<" size is: " << (end-begin) << " bytes.\n";
}
int main ()
{
test_write_read_cin_getline();
test_write();
test_write_read_getline();
string file("TheMisteryMethod.txt");
GetSizeOfFile(file);
return 0;
}
/**********************************
程序运行结果如下：
Writing to the file
Enter your name: wangshihui
Enter your age: 22
Reading from the file
wangshihui
22
wangshihui
22
To recap, the three main objectives in the Mystery Method are:
To attract a woman
To establish comfort, trust, and connection
To structure the opportunity to be seduced
A woman's number-one emotional priority is safety and security.
TheMisteryMethod.txt size is: 294 bytes.
Process returned 0 (0x0) execution time : 13.100 s
Press any key to continue.
***********************************/
#include <fstream>
#include <iostream>
using namespace std;
void test_write_read_cin_getline()
{
char data[100];
// open a file in write mode.
ofstream outfile;
outfile.open("TheMisteryMethod.txt");
cout << "Writing to the fi
补充：软件开发 , C++ ,
