ifstream.cpp

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#include <fstream>    // for fstream
#include <iomanip>    // for setw
#include <ios>        // for dec, hex, oct, right, showbase
#include <iostream>   // for cerr, cout
#include <locale>     // for isspace()
 
#include <examples.h>
 
 
int main ( )
{
    const char ntbs[] = "Le minot passait la piece a frotter.";
 
    try {
 
        // create a read/write file-stream object
        std::ifstream in ("ifstream.results.out",
                          std::ios::in | std::ios::out | std::ios::trunc);
 
        if (!in.is_open ()) 
            throw (std::ios::failure ("open error"));
 
        // associate the ostream object's buffer with the ifstream object
        std::ostream out (in.rdbuf ());   
 
        // output ntbs in out
        out << ntbs << '\n';
 
        // seek to the beginning of the file
        in.seekg (0);
 
        char c;
 
        // output each space-separated word on a separate line
        while (in.get (c)) {
            if ((std::isspace)(c, in.getloc ())) 
                std::cout << '\n';
            else
                std::cout << c;
        }
 
        std::cout << '\n';
 
        // clear stream state, failbit | eofbit set by last call to get ()
        in.clear ();
 
        // move back to the beginning of the file
        in.seekg (0); 
 
        char buf [40];
 
        // guard against buffer overflow
        in.width (sizeof buf);
 
        // set right justification
        std::cout << std::right;
 
        // does the same thing as the previous code
        // output each word on a separate line in a field of width 10
        while (in >> buf) {
            std::cout.width (10);
            std::cout << buf << '\n';
        }
    
        std::cout << '\n';
 
        // clear the stream state
        in.clear (); 
 
        // output the base info before each integer
        out << std::showbase;
 
        std::ostream::pos_type pos= out.tellp ();
 
        const long x = 10;
        
        // output x in hex with a field with of 10 
        out << std::hex << std::setw (10) << x << '\n';
 
        // output x in oct with a field with of 10
        out << std::oct << std::setw (10) << x << '\n';
 
        // output x in dec with a field with of 10
        out << std::dec << std::setw (10) << x << '\n';
 
        // move back to the beginning of the file
        in.seekg (0);
 
        // output the entire file
        std::cout << in.rdbuf () << '\n';
 
        // clear the stream state
        in.clear (); 
 
        // seek the input sequence to pos  
        in.seekg (pos);
  
        long a = 0;
        long b = 0;
        long d = 0;
 
        in.unsetf (std::ios::basefield);
 
        // read the previous outputted integer
        in >> a >> b >> d;
 
        // output 3 times 10
        std::cout << a << '\n' << b << '\n' << d << '\n';
    }
    catch (std::ios::failure e) {
        std::cerr << e.what () << '\n';
    }
 
    return 0;
}