Problem when passing by reference

[capricious_001]

Hey Guys, It must be a very simple mistake I am making however I am receiving a problem when passing a LPSTR value by reference. I have 2 functions. Below are their prototypes:

bool GetRSLocation_Reg(LPSTR&);
bool retrieveLogFileLocation(LPSTR&);

//Call main and do some other stuff

LPSTR RegLocation

if(GetRSLocation_Reg(RegLocation)){
cout << "The output of the RegLocation var is correct here: " << RegLocation << endl;
if(retrieveLogFileLocation(RegLocation)){
//Success
}
}

The first function returns in a file path and assigns it to a LPSTR variable by reference. When outputting the referenced value WITHIN the function definition of "GetRSLocation_Reg" to console, it is correct. Before the "retreiveLogFileLocation" function is called, RegLocation also returns the correct value. However within function definition for retreiveLogFileLocation, the contents of the variable RegLocation have changed. It appears to be holding gibberish :s Would anyone know what I am doing wrong that is causing this? Thanks Robbie

[Viorel]

Probably within the GetRSLocation_Reg function you assign a temporary string (maybe allocated on the stack) to the RegLocation pointer. This string cannot be used after exiting from function, because the stack is reused by other calls. You can try another way, by allocating a space for RegLocation before calling the function:

bool GetRSLocation_Reg(LPSTR location)
{
    . . .
    strcpy(location, .....);
    return true;
}

char RegLocation[256]; // allocate enough space
if(GetRSLocation_Reg(RegLocation))
{
    . . .
}

Alternatively, you can use CString class (in MFC projects) or std::string class from STL.

[capricious_001]

Hey Viorel, Thats exactly what the issue was and I'm quite surprised I didnt see that! I made the changes and everything works perfectly. Thanks! Robbie

[ThatsAlok]

capricious_001 wrote:

bool GetRSLocation_Reg(LPSTR&); bool retrieveLogFileLocation(LPSTR&);

this seems to be pointer to pointer problem.. i.e. LPSTR itself is pointer and then you refrencing that also.

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

cheers, Alok Gupta VC Forum Q&A :- I/ IV Support CRY- Child Relief and You

[ThatsAlok]

capricious_001 wrote:

bool GetRSLocation_Reg(LPSTR&;); bool retrieveLogFileLocation(LPSTR&;);

this seems to be pointer to pointer problem.. i.e. LPSTR itself is pointer and then you refrencing that also.

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

cheers, Alok Gupta VC Forum Q&A :- I/ IV Support CRY- Child Relief and You

[Hamid Taebi]

if you want to use LPTSTR use LPTSTR lpt; lpt=LocalAlloc(LPTR,size); and use lpt.... in the endLocalFree(lpt);_**

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whitesky

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