Re: converting 1944 to '1','9','4','4'

From: Leor Zolman (leor_at_bdsoft.com)
Date: 04/14/04 

Date: Wed, 14 Apr 2004 14:17:32 GMT

On Wed, 14 Apr 2004 14:10:49 +0200, Rolf Magnus <ramagnus@t-online.de>
wrote:

>Leor Zolman wrote:
>
>> On Tue, 13 Apr 2004 15:36:30 +0000 (UTC), Christopher Benson-Manica
>> <ataru@nospam.cyberspace.org> wrote:
>>
>>>Leor Zolman <leor@bdsoft.com> spoke thus:
>>>
>>>> int y = 1944;
>>>> char buffer[10];
>>>> sprintf(buffer, "%d", y);
>>>
>>>No problem in this case, but on my system, INT_MAX is 2147483647,
>>>which is too big to fit in a 10-character buffer :)
>> Oops.
>
>Can you even imagine how much money that kind of "oops" has already
>destroyed? :-)

I only really started using std::string in earnest following a series of
pathname-related overrun bugs in the "Proxy" CL.EXE I distribute with
STLFilt, and I must admit I niether use nor miss fixed-sized C-string
buffers much any more. The ill-advised undersized buffer in my original
response here probably resulted from my brain seeing "1944", thinking
"years", and then upping the size a bit more for "safety".

If I did this sort of thing a lot today, which I actually don't, then I'd
be worried in general about buffer overruns and probably abstract out the
T-to-string conversion into a utility template library. Here's a first cut,
along with a test driver:

//
// tostring.h:
// T-to-std::string and T-to-char* conversion library
//
// Synopsis:
//
// std::string toString(const T &t);
// Converts t to std::string via operator<<
//
// char *toCString(char *dest, const T&t);
// Converts T to C-style string at dest, returns
// dest (calls toString above).
//
// Version 0.1
// Leor Zolman, 4/14/2004
//

#ifndef TOSTRING_H
#define TOSTRING_H

#include <sstream>
#include <string>

template<typename T>
std::string toString(const T& t)
{
    std::ostringstream os;
    os << t;
    return os.str();
}

template<typename T>
inline char *toCString(char *dest, const T&t)
{
    return strcpy(dest, toString(t).c_str());
}

/*
// This one we'd only ever want for performance reasons:
std::string toString(const std::string &t)
{
    return t;
}
*/

// And this covers the last pathological case:
inline const char *toCString(const char *t)
{
    return t;
}

#endif

//
// tostrtest.cpp: Test tostring.h library
//

#include "tostring.h"

int main()
{
    using namespace std;

    char buffer[1000]; // ;-)

    int y = 1944;
    strcpy(buffer, toString(y).c_str());
    cout << "from int: " << buffer << endl;
    cout << "from int: " << toCString(buffer, y) << endl;

    double d = 1944.44;
    strcpy(buffer, toString(d).c_str());
    cout << "from double: " << buffer << endl;
    cout << "from double: " << toCString(buffer, d) << endl;

    string s = "1944 was a great year";
    strcpy(buffer, toString(s).c_str());
    cout << "from a string: " << buffer << endl;
    cout << "from a string: " << toCString(buffer, s) << endl;

    strcpy(buffer, toString("this is a dumb").c_str());
    cout << "from a char *: " << buffer << endl;
    cout << "from a char *: " <<
            toCString(buffer, "another dumb one") << endl;

    return 0;
}

        -leor 

-- 
Leor Zolman --- BD Software --- www.bdsoft.com
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