Re: printf and cout

From:
James Kanze <james.kanze@gmail.com>
Newsgroups:
comp.lang.c++
Date:
Thu, 27 Mar 2008 01:57:35 -0700 (PDT)
Message-ID:
<9268a481-fa44-400a-a2cf-faa3731ecf5b@z38g2000hsc.googlegroups.com>
On Mar 26, 11:50 pm, Paul Brettschneider
<paul.brettschnei...@yahoo.fr> wrote:

laikon wrote:

this is about overflow in C and C++.

int c = 400;
printf("%c", c);

it print ? on screen, and ascii of '?' is 63.

but
cout << int(char(400));

it print -112 on screen.


These two things are not the same at all.
The printf version should read like this:

#include <cstdio>

int main()
{
        int c = 400;
        printf("%d", (char)400);
}

And, not surprisingly, it prints -112 too (on a 2s complement machine).


On a 2's complement machine with 8 bit bytes, where plain char
is signed. Exceptions to the first two conditions are fairly
rare today. But unsigned plain char is an option with a lot of
compilers, and the default on some as well (and would make life
a lot easier if you could count on it).

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James Kanze (GABI Software) email:james.kanze@gmail.com
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