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77123036@163.com · Guest

#include <iostream>
#include <fstream>
using namespace std;

int main()
{
fstream inOut( "copy.out", ios_base::in|ios_base::app );
int cnt=0;
char ch;
inOut.seekg(0);
while ( inOut.get( ch ) )
{
cout.put( ch );
cnt++;
if ( ch == 'n' )
{
ios_base::pos_type mark = inOut.tellg();
/*here is an error , but if replace with
"ios::pos_type mark = inOut.tellg();"
it will work well .
can you tell me why?
*/
inOut << cnt << ' ';
inOut.seekg( mark );
}
}
inOut.clear();
inOut << cnt << endl;
cout << "[ " << cnt << " ]n";
system("pause");
return 0;
}

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Llewelly · Guest

"77123036 (AT) 163 (DOT) com" <77123036 (AT) 163 (DOT) com> writes:

Albrecht Fritzsche · Guest

template <class Elem, class Tr = char_traits
class basic_ios : public ios_base
{ ... };

and

typedef basic_ios<char, char_traits ios;

So, as you easily can see, both classes aren't the same. While the
std::ios_base is a non-template base class defining several flags,
types, ... is std::ios already char centric.

Since pos_type is defined in ios everything is ok - you should check a
C++ reference next to your place!

Ali

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Ryan Gallagher · Guest

check out the dinkumware reference for your answer:
http://www.dinkumware.com/manuals/reader.aspx?b=p/&h=ios.html

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