Please comment on my integer to string code.

**red floyd** · Mar 9 '06, 05:05 PM

Re: Please comment on my integer to string code.

manoj1978@gmail .com wrote:[color=blue]
> Hi All,
> I wrote the following to print an integer in its string
> representation for base -36 to 36.
>
> [code redacted][/color]

How do you display numbers in a *negative* base?????

**manoj1978@gmail.com** · Mar 9 '06, 05:25 PM

Re: Please comment on my integer to string code.

red floyd wrote:
[color=blue]
> manoj1978@gmail .com wrote:[color=green]
> > Hi All,
> > I wrote the following to print an integer in its string
> > representation for base -36 to 36.
> >
> > [code redacted][/color]
>
> How do you display numbers in a *negative* base?????[/color]

Consider negadecimal.

27 will be 187

since 187 = 1 * -10 * -10 + 8 * -10 + 7 = 27.

**Phlip** · Mar 9 '06, 05:25 PM

Re: Please comment on my integer to string code.

manoj1978@gmail .com wrote:
[color=blue]
> int main()
> {
> for(int i = -55; i <= 55; i++)
> {
> cout << i << " = ";
> printBase(i,-10);
> }
> }[/color]

Unit tests are the most important aspect of programming. Your printBase
should return a string, so you can test it, and so it won't "couple" with
its environment. Here you have some cout outside printBase, and some
inside. Move all outside, then write unit tests like these:

assert("whateve r" == printBase(-55);
assert("whateve r" == printBase(-55);
assert("whateve r" == printBase(-55);
assert("whateve r" == printBase(-55);

Now each time you change the program, run those tests. If you make certain
kinds of mistakes (but not any mistake) the test will catch you, and you
can use Undo to get rid of the mistake. Undo is much more efficient than
debugging.

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

**manoj1978@gmail.com** · Mar 9 '06, 05:35 PM

Re: Please comment on my integer to string code.

Phlip wrote:
[color=blue]
> Unit tests are the most important aspect of programming. Your printBase
> should return a string, so you can test it, and so it won't "couple" with
> its environment. Here you have some cout outside printBase, and some
> inside. Move all outside, then write unit tests like these:
>
> assert("whateve r" == printBase(-55);
> assert("whateve r" == printBase(-55);
> assert("whateve r" == printBase(-55);
> assert("whateve r" == printBase(-55);
>
> Now each time you change the program, run those tests. If you make certain
> kinds of mistakes (but not any mistake) the test will catch you, and you
> can use Undo to get rid of the mistake. Undo is much more efficient than
> debugging.
>
> --
> Phlip
> http://www.greencheese.org/ZeekLand <-- NOT a blog!!![/color]
Hi Philip,
Thanks.I will surely keep this in mind.
This time I had the expected results in a file.
I was redirecting the output and doing file compare.
Regards,
manoj.

**Victor Bazarov** · Mar 9 '06, 05:45 PM

Re: Please comment on my integer to string code.

Phlip wrote:[color=blue]
> manoj1978@gmail .com wrote:
>
>[color=green]
>>int main()
>>{
>> for(int i = -55; i <= 55; i++)
>> {
>> cout << i << " = ";
>> printBase(i,-10);
>> }
>>}[/color]
>
>
> Unit tests are the most important aspect of programming. Your printBase
> should return a string, so you can test it, and so it won't "couple" with
> its environment. Here you have some cout outside printBase, and some
> inside. Move all outside, then write unit tests like these:
>
> assert("whateve r" == printBase(-55);
> assert("whateve r" == printBase(-55);
> assert("whateve r" == printBase(-55);
> assert("whateve r" == printBase(-55);[/color]

Why four of them in a row? Are there side effects expected that affect
the behaviour of the function?
[color=blue]
> Now each time you change the program, run those tests. If you make certain
> kinds of mistakes (but not any mistake) the test will catch you, and you
> can use Undo to get rid of the mistake. Undo is much more efficient than
> debugging.[/color]

V
--
Please remove capital As from my address when replying by mail

**Phlip** · Mar 9 '06, 05:56 PM

Re: Please comment on my integer to string code.

Victor Bazarov wrote:
[color=blue][color=green]
>>assert("whate ver"Â ==Â printBase(-55);
>>assert("whate ver"Â ==Â printBase(-55);
>>assert("whate ver"Â ==Â printBase(-55);
>>assert("whate ver"Â ==Â printBase(-55);[/color]
>
> Why four of them in a row?Â Â AreÂ thereÂ sideÂ effectsÂ expectedÂ thatÂ affect
> the behaviour of the function?[/color]

I forgot to edit:

assert("whateve r" == printBase(-55));
assert("whateve r" == printBase(-54));
assert("whateve r" == printBase( -1));
assert("whateve r" == printBase( 0));
...

The next, more complex topic is: How to make sure the tests use enough
inputs to exercise all the branches in the code. Don't go there. ;-)

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

**Ben Pope** · Mar 9 '06, 06:05 PM

Re: Please comment on my integer to string code.

Phlip wrote:[color=blue]
>
> The next, more complex topic is: How to make sure the tests use enough
> inputs to exercise all the branches in the code. Don't go there. ;-)[/color]

Classification trees and code coverage tests. Don't know of any free
software to do that.

Ben Pope
--
I'm not just a number. To many, I'm known as a string...

**Pete Becker** · Mar 9 '06, 06:15 PM

Re: Please comment on my integer to string code.

Phlip wrote:
[color=blue]
>
> The next, more complex topic is: How to make sure the tests use enough
> inputs to exercise all the branches in the code. Don't go there. ;-)
>[/color]

Especially since branch testing is known to be inadequate. <g>

--

Pete Becker
Roundhouse Consulting, Ltd.

**Phlip** · Mar 9 '06, 06:45 PM

Re: Please comment on my integer to string code.

Pete Becker wrote:
[color=blue]
> Especially since branch testing is known to be inadequate. <g>[/color]

Inadequate for converting an integer to a string???

<vbgd&rc>

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

**Pete Becker** · Mar 9 '06, 07:35 PM

Re: Please comment on my integer to string code.

Phlip wrote:
[color=blue]
> Pete Becker wrote:
>
>[color=green]
>>Especially since branch testing is known to be inadequate. <g>[/color]
>
>
> Inadequate for converting an integer to a string???
>[/color]

Certainly inadequate as a testing discipline in general, and almost
certainly inadequate for testing a function that converts an integer to
a string. Whether it gives you adequate coverage in any particular case
depends on the case. Applied to the original code it is inadequate.

For example, branch analysis could be satisfied with test cases that
only exercise the do loop exactly twice: once to branch back to the head
of the loop and once to branch out of it. That doesn't test what happens
when you need exactly one digit or three or more digits to represent the
value. Of course, doing that one thoroughly requires path testing, which
is known to be prohibitively expensive <g>, although perhaps workable
for this example.

For another example, if the charTable had some incorrect values, a test
suite based only on branch testing wouldn't necessarily find them.

--

Pete Becker
Roundhouse Consulting, Ltd.

**Dietmar Kuehl** · Mar 9 '06, 07:55 PM

Re: Please comment on my integer to string code.

Phlip wrote:[color=blue]
> Inadequate for converting an integer to a string???[/color]

At least insufficient. For example, branch testing would not detect
the error which is in the original code when passing
'std::numeric_l imits<int>::min ()': the value range for integers is
[normally] asymmetric and "i = -i" is the identity operation for
the two values '0' and 'std::numeric_l imits<int>::min ()' (well, for
the latter value the behavior may actually be undefined or
implementation defined). That is, in addition to branch testing you
need to perform at least some testing for corner cases.
--
<mailto:dietmar _kuehl@yahoo.co m> <http://www.dietmar-kuehl.de/>
<http://www.eai-systems.com> - Efficient Artificial Intelligence

**Phlip** · Mar 9 '06, 08:35 PM

Re: Please comment on my integer to string code.

Dietmar Kuehl wrote:
[color=blue]
> That is, in addition to branch testing you
> need to perform at least some testing for corner cases.[/color]

Tiny little voice: Then add, uh, branches inside the code to handle or throw
the corner cases...

But thanks guys - I put both yours and Pete's answers on a Wiki page
BranchTesting. For some strange reason no page by that name was there
yet. ;-)

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

**BobR** · Mar 9 '06, 09:55 PM

Re: Please comment on my integer to string code.

manoj1978@gmail .com wrote in message
<1141916757.291 734.248560@p10g 2000cwp.googleg roups.com>...[color=blue]
>Hi All,
> I wrote the following to print an integer in its string
>representati on for base -36 to 36.
> Please comment on this code.
>
>#include <iostream>
>#include <string>
>[/color]
// >using std::abs;[color=blue]
>using std::cout;
>using std::endl;[/color]
// >using std::reverse;[color=blue]
>using std::string;[/color]

Style-wise, **IMHO**, (at this point) it stinks!! I'd put the 'using *'
inside the function/main if I couldn't type "std::".
My suggestions inline below.
[color=blue]
>[/color]
// >char charTable[] = "0123456789ABCD EFGHIJKLMNOPQRS TUVWXYZ";

std::string charTable( "0123456789ABCD EFGHIJKLMNOPQRS TUVWXYZ" );
[color=blue]
>[/color]
// >void printBase(int i, int base){
std::string CalcBase(int i, int base){
using std::abs; // etc.
[color=blue]
> if ((abs(base) <= 1) || (abs(base) > 36) || (i == 0)){[/color]
// > cout << "0" << endl;
// > return;
return "0";[color=blue]
> }
>
> string str = "";
> if ((base > 0) && (i < 0)){
> str += "-"; // prints "-16 = 10-" for base==16
> i = -i;
> }
>
> do {
> if (i % base >= 0){[/color]
// > str += charTable[i % base];
str += charTable.at( i % base );
[color=blue]
> i = i / base;
> } else {[/color]
// > str += charTable[i % base - base];
str += charTable.at( i % base - base );
[color=blue]
> i = i /base + 1;
> }
> } while(i);[/color]
// > reverse(str.beg in(), str.end());
std::reverse(st r.begin(), str.end());

// prints "-16 = 10-" for base==16

// > cout << str << endl;
return str;[color=blue]
> } // CalcBase(int,in t)
>
>int main(){[/color]

try{
for(int i(-55); i <= 55; ++i){
// > cout << i << " = ";
// > printBase( i, -10 );
std::cout << i <<" = "<<CalcBase ( i, -10 )<<std::endl;
[color=blue]
> } // for(i)[/color]
} // try
catch(std::out_ of_range &Oor){
std::cerr<<"cau ght "<<Oor.what()<< std::endl;
return EXIT_FAILURE;
}
catch(...){
std::cerr<<"cau ght ... something"<<std ::endl;
return EXIT_FAILURE;
}
return 0;
[color=blue]
> } // main()end
>
>Thanks and Regards,
>manoj.[/color]

// - output - (base==-10)
-55 = 65
-54 = 66
[snip]
-11 = 29
-10 = 10
-9 = 11
-8 = 12
[snip]
-2 = 18
-1 = 19
0 = 0
1 = 1
[snip]
8 = 8
9 = 9
10 = 190
11 = 191
[snip]
54 = 154
55 = 155

And your C++ problem is?

--
Bob R
POVrookie

**Phlip** · Mar 9 '06, 09:55 PM

Re: Please comment on my integer to string code.

BobR wrote:
[color=blue]
> catch(...){
> std::cerr<<"cau ghtÂ ...Â something"<<std ::endl;
> returnÂ EXIT_FAILURE;
> }[/color]

I know a certain lead programmer driven to distraction by code that relied
on catch(...). The advice is let the program halt; use a debugger to fix
all root causes, and stress-test applications to force out these risks.

And catch(...) only catches hardware crashes on Win32 as a compiler-specific
extension. Other platforms just dump core, meaning they cannot use that
trick to maintain their work loops and keep running.

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

Please comment on my integer to string code.

Please comment on my integer to string code.

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