cout true for bool(true)

**Phlip** · Nov 2 '06, 05:45 AM

Re: cout true for bool(true)

Gary Wessle wrote:

how can I
>
bool a(true);
cout << a;
>
and expect it to print out
>
true
>
and not just
>
1

Before someone provides a cheaper answer, may I ask if one might imbue a
locale?

(Note that some cultures don't call a positive boolean "true" ;-)

--
Phlip
http://www.greencheese.us/ZeekLand <-- NOT a blog!!!

**Sumit Rajan** · Nov 2 '06, 05:55 AM

Re: cout true for bool(true)

Gary Wessle wrote:

Hi
how can I
>
bool a(true);
cout << a;
>
and expect it to print out
>
true
>
and not just
>
1

Something like this?

bool a = true;
std::cout.setf( std::ios::boola lpha);
std::cout << a << "\n";

Regards,
Sumit.

**Jacek Dziedzic** · Nov 2 '06, 09:45 AM

Re: cout true for bool(true)

Gary Wessle wrote:

Hi
how can I
>
bool a(true);
cout << a;
>
and expect it to print out
>
true
>
and not just
>
1

Output the manipulator 'boolapha' to the 'cout' stream
before outputting your booleans. Also make sure you
#include <iomanip>.

HTH,
- J.

**Salt_Peter** · Nov 2 '06, 02:15 PM

Re: cout true for bool(true)

Gary Wessle wrote:

Hi
how can I
>
bool a(true);
cout << a;
>
and expect it to print out
>
true
>
and not just
>
1
>

The cheap answer Phillip was referring to is:

std::cout << a ? "true" : "false";

**Victor Bazarov** · Nov 2 '06, 02:25 PM

Re: cout true for bool(true)

Salt_Peter wrote:

Gary Wessle wrote:

>Hi
>how can I
>>
>bool a(true);
>cout << a;
>>
>and expect it to print out
>>
>true
>>
>and not just
>>
>1
>>

>
The cheap answer Phillip was referring to is:
>
std::cout << a ? "true" : "false";

Should probably be parenthesized:

std::cout << (a ? "true" : "false");

V
--
Please remove capital 'A's when replying by e-mail
I do not respond to top-posted replies, please don't ask

**Rolf Magnus** · Nov 2 '06, 04:35 PM

Re: cout true for bool(true)

Victor Bazarov wrote:

Salt_Peter wrote:

>Gary Wessle wrote:

>>Hi
>>how can I
>>>
>>bool a(true);
>>cout << a;
>>>
>>and expect it to print out
>>>
>>true
>>>
>>and not just
>>>
>>1
>>>

>>
>The cheap answer Phillip was referring to is:
>>
>std::cout << a ? "true" : "false";

>
Should probably be parenthesized:
>
std::cout << (a ? "true" : "false");

Yup. That's one of those places where operator abuse can stab you in the
back.

PS: Yes, using bit shift operators for stream I/O counts as operator abuse
in my eyes.

**Markus Moll** · Nov 2 '06, 05:15 PM

Re: cout true for bool(true)

Hi

Jacek Dziedzic wrote:

Output the manipulator 'boolapha' to the 'cout' stream
before outputting your booleans. Also make sure you
#include <iomanip>.

Actually, there is no need to #include <iomanip>, as std::boolalpha is
declared in header <ios>, which must be included by <ostream(if my
understanding is correct).

Cheers
Markus

**jjds101@yahoo.com** · Nov 2 '06, 05:25 PM

Re: cout true for bool(true)

Rolf Magnus wrote:

Victor Bazarov wrote:
>

std::cout << (a ? "true" : "false");

>
Yup. That's one of those places where operator abuse can stab you in the
back.
>
PS: Yes, using bit shift operators for stream I/O counts as operator abuse
in my eyes.

Heh...

Is it still abuse if you call them insertion/extraction operators?
What else would one use?

**Markus Moll** · Nov 2 '06, 05:35 PM

Re: cout true for bool(true)

Hi

Phlip wrote:

Before someone provides a cheaper answer, may I ask if one might imbue a
locale?
>
(Note that some cultures don't call a positive boolean "true" ;-)

I'm just curious, have you seen an implementation where the output would not
be "true" and "false" for some locale? I have tried it here, because I
somehow expected "vrai"/"faux", "juist"/"fout", "wahr"/"falsch" and alike.
(I was disappointed, it was always "true"/"false")

Markus

**Jacek Dziedzic** · Nov 2 '06, 09:55 PM

Re: cout true for bool(true)

Markus Moll wrote:

Hi
>
Jacek Dziedzic wrote:
>

> Output the manipulator 'boolapha' to the 'cout' stream
>>before outputting your booleans. Also make sure you
>>#include <iomanip>.

>
>
Actually, there is no need to #include <iomanip>, as std::boolalpha is
declared in header <ios>, which must be included by <ostream(if my
understanding is correct).

Thanks, I didn't realize that.

- J.

**Phlip** · Nov 3 '06, 03:35 AM

Re: cout true for bool(true)

Markus Moll wrote:

I'm just curious, have you seen an implementation where the output would
not
be "true" and "false" for some locale? I have tried it here, because I
somehow expected "vrai"/"faux", "juist"/"fout", "wahr"/"falsch" and alike.
(I was disappointed, it was always "true"/"false")

Post your code. Maybe "true" and "false" are considered data, not human
interface, so the locales don't affect them.

I never studied this topic; I just wanted to learn more about locales.

--
Phlip
http://www.greencheese.us/ZeekLand <-- NOT a blog!!!

**Markus Moll** · Nov 3 '06, 10:25 AM

Re: cout true for bool(true)

Hi

Phlip wrote:

Post your code. Maybe "true" and "false" are considered data, not human
interface, so the locales don't affect them.

--- snip code 1 ---

#include <iostream>
#include <ostream>
#include <locale>

using namespace std;

int main()
{
locale loc("");
if(has_facet<nu mpunct_byname<c har(loc))
{
cout << "Decimal point: " << use_facet<numpu nct_byname<char >

>(loc).decimal_ point() << "\n";

cout << "Truename: " << use_facet<numpu nct_byname<char >

>(loc).truename () << "\n";

cout << "Falsename: " << use_facet<numpu nct_byname<char >

>(loc).falsenam e() << "\n";

}
}

--- snip ---

--- snip code 2 ---

#include <iostream>
#include <ostream>
#include <locale>

using namespace std;

int main()
{
locale loc("");
cout.imbue(loc) ;
cout << boolalpha << true << " " << false << " " << 1000000 << endl;
}

--- snip ---

Output for code 2 for example was:

$ LC_ALL=fr_FR ./code2
true false 1000000
$ LC_ALL=en_GB ./code2
true false 1,000,000
$ LC_ALL=de_DE ./code2
true false 1.000.000

Markus

**Roland Pibinger** · Nov 3 '06, 11:15 AM

Re: cout true for bool(true)

On 2 Nov 2006 09:39:21 -0800, jjds101@yahoo.c om wrote:

>Rolf Magnus wrote:

>Victor Bazarov wrote:
>>

std::cout << (a ? "true" : "false");

>>
>Yup. That's one of those places where operator abuse can stab you in the
>back.
>>
>PS: Yes, using bit shift operators for stream I/O counts as operator abuse
>in my eyes.

>
>Heh...
>
>Is it still abuse if you call them insertion/extraction operators?
>What else would one use?

+= or no operator at all (just print())? I agree with Rolf Magnus on
operator overloading abuse in iostreams.

Best wishes,
Roland Pibinger

**shadowman615@comcast.net** · Nov 3 '06, 02:55 PM

Re: cout true for bool(true)

Roland Pibinger wrote:

On 2 Nov 2006 09:39:21 -0800, jjds101@yahoo.c om wrote:

Rolf Magnus wrote:

Victor Bazarov wrote:
>
std::cout << (a ? "true" : "false");
>
Yup. That's one of those places where operator abuse can stab you in the
back.
>
PS: Yes, using bit shift operators for stream I/O counts as operator abuse
in my eyes.

Heh...

Is it still abuse if you call them insertion/extraction operators?
What else would one use?

>
+= or no operator at all (just print())? I agree with Rolf Magnus on
operator overloading abuse in iostreams.
>

// test1.cpp
#include <iostream>

int main() {
int a = 1;
std::cout += a;
return 0;
}

g++ test1.cpp

test1.cpp: In function `int main()':
test1.cpp:5: error: no match for 'operator+=' in 'std::cout += a'

cout true for bool(true)

cout true for bool(true)

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