返回文件起始位置

[zedzhao]

#include <iostream>
using namespace std;

#include <fstream>
using namespace std;


ifstream& open_file(ifstream& ,const string);


int main()
{
	ifstream ifile;
	open_file(ifile,"t.txt");

	char ch;

	ifstream::pos_type mark = ifile.tellg();
	while(ifile.get(ch))
		cout << ch << " ";
	ifile.seekg(mark);	//mark换成 ios_base::beg也不行？？

	cout << endl;
	while(ifile.get(ch))
		cout << ch << " ";

	
	ifile.close();
}

ifstream& open_file(ifstream &in,const string fileName)
{
	in.close();
	in.clear();

	in.open(fileName.c_str(),ios::in);

	if(!in)
		cerr <<"can't open file" <<in<<endl;
	return in;
}
应该seekg()函数就可以 ，这里有什么问题啊？ seekg(0,ios_base::beg)也不行的

[lann64]

没什么问题，加上，ifile.clear()

[lann64]

#include <iostream>
using namespace std;

#include <fstream>
using namespace std;


ifstream& open_file(ifstream& ,const string);


int main()
{
    ifstream ifile;
    open_file(ifile,"t.txt");

    char ch;

    ifstream::pos_type mark = ifile.tellg();
    while (ifile.get(ch))  //这里把EOF置位了
        cout << ch << " ";
    ifile.clear();         //不清除EOF置位，后面的文件操作直接被跳过去，不会实际执行。
    ifile.seekg(mark);    //mark换成 ios_base::beg也不行？？

    cout << endl;
    while (ifile.get(ch))
        cout << ch << " ";


    ifile.close();
}

ifstream& open_file(ifstream &in,const string fileName)
{
    in.close();
    in.clear();

    in.open(fileName.c_str(),ios::in);

    if (!in)
        cerr <<"can't open file" <<in<<endl;
    return in;
}

[zedzhao]

3Q