Small problems formatting maps (<map>)

[DavidKrutsko]

Hey,

consider the following chunk of code

[code]
#define CONSTANT 5

void func (const char *Code)
{
map <pChar, pChar> Codes;
Codes["A100"] = "SOMETHING\n";
Codes["A101"] = "ANOTHER SOMETHING", CONSTANT, "\n";

if (Codes.find(Code) != Codes.end())
fprintf_s (stderr, Codes

);
    else fprintf_s (stderr, "SOMETHING" );
}
 

Alright this is swell but...
my problem is that whenever i call

func ("A101");
 

I can only see "ANOTHER SOMETHING " as my output without printing "5" since thats what CONSTANT is.....

How can i print out everythign in A101?

thanks --

DK --

[DavidKrutsko]

*SOLUTION*

Alright i was thinking about this for a long time and figured out what i can do.... here is what i did....

#define Number 8
typedef char* pChar;
 
// converts a string into a pChar
pChar StrpChar (string InStr)
{
    return _strdup(InStr.c_str());
}
 
// Converts integer into a pChar
pChar StrInt (__int64 InNum)
{
ostringstream oStr;
oStr << InNum;
 
return StrpChar(oStr.str());
 }
 
void func (const pChar Code)
{
string sNumber = StrInt(Number);
map <pChar, string> Codes;Codes["A100"] = "text " + sNumber + " more text\n";if (Codes.find(Code) != Codes.end())fprintf_s (stderr, StrpChar(ErrorCodes[ErrorCode]));else;
 
Quit;
 }
 

alright there now you can use maps just like couts and still using fprintf_s to do it...

P.S. im creating an errorcodes table in order to be able to see and modify error messages in my program easier rather then hardcoding every error string in manually.... :)

DK--

[RRick]

When I first saw the map<char*, char*> I shuttered thinking about all the ways this could go wrong. Memory leaks, shallow copies, etc. etc. One simple tip: Use C++ strings not char * for you data and especially for your keys (see below).

The char* key comparison is an address comparison, not a value comparison. (Can someone else verify this?) When you access the key as "A101" you'll get an static address. If you put "A101" in a local string, then the address will change and key will fail. I don't think this is what you want.

string val = Codes["A101"];    //  Works
char buff[5];  strncpy( buff, 5, "A101");
string val2 = Codes[buff];      // Fails, possibly crash & burn
 

[weaknessforcats]

The char* key comparison is an address comparison, not a value comparison. (Can someone else verify this?)

Yes. map is a key/value container. If your key is a char*, then the comparison is based on the address inside the char*. Not good. Your advice to ue C++ string objects was exactly correct.

map<string, string> mymap;