🚀 go-pugleaf

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Organization : California Institute of Technology
Keywords:

    The C++ book claims (sec 8.4.4; page 240) that

   "...cin is tied to cout; this means that cin executes a
	cout.flush();	// write output buffer
    before attempting to read characters from its file."

    Playing with various forms of stream I/O leaves me	puzzled  about
this assertion. Consider the following example:

__@/ cat junk.c
#include <stream.h>
main()
{
    char buf[120];

    //	Test buffering of get(char *, int)
    //	Should read and echo two lines
    for (int i = 0; i < 2; i++) {
	cin.get(buf, 120);
	cout << "get(char *, int): " << buf << "\n";
    }

    //	Test buffering of get(char &)
    //	Should also read and echo two lines
    for (i = 0; i < 2; i++) {
	    int j = 0;
	    while (!cin.eof()) {
		cin.get(buf[j++]);
		if (buf[j-1] == '\n')
		    break;
	    }
	    buf[j - 1 + cin.eof()] = '\0';
	    cout << "get(char &): " << buf << "\n";
    }
}
__@/ junk
This is line 1	    < I type this
This is line 2	    < and this
This is line 3	    < and this (no EOF)
get(char *, int): This is line 1    < THEN, it prints out these lines
get(char *, int):
get(char &):
get(char &): This is line 2

    I expected something more like

This is line 1
get(char *, int): This is line 1
This is line 2
get(char *, int): This is line 2
This is line 3
get(char &): This is line 3
This is line 4
get(char &): This is line 4

    Can anyone tell me why cout is not buffered as the book  seems  to
claim it should be, or why the middle two read operations got  nothing
at all?  I don't understand this at all.

    Thanks,
    Jon Leech (jon@csvax.caltech.edu || ...seismo!cit-vax!jon)
    __@/