C ++ Borland char *和strcpy

Question

char *dum[32];
strcpy(&dum,InstList->Lines->Text.c_str());

InstList is a TMemo of C++ Builder

Why am I getting this error?

[C++ Error] emulator.cpp(59): E2034 Cannot convert 'char * *' to 'char *' Full parser context emulator.cpp(56): parsing: void _fastcall TMain::Button1Click(TObject *)

Answer 1

char *dum[32];

is an array of length 32, each element being a char* . I guess you meant to write

char dum[32];

This is an array of 32 char and you can then write:

strcpy(dum, InstList->Lines->Text.c_str());

Make sure, of course, InstList->Lines->Text is not so big that it overflows your buffer.

Of course, I'm not sure why you would need to use C strings in a C++ program.

Answer 2

You either use (prone to serious security problem called buffer overflow )

char dum[32];
strcpy(dum,InstList->Lines->Text.c_str());

OR (much better since it works with any length without being prone to a serious security problem called buffer overflow )

// C style
// char *dum = malloc(strlen(InstList->Lines->Text.c_str())+1); 

// BCB style...
char *dum = malloc(InstList->Lines->Text.Length()+1);  

// BEWARE: AFTER any malloc you should check the pointer returned for being NULL

strcpy(dum,InstList->Lines->Text.c_str());

EDIT - as per comments:

I am assuming that you are using an older BCB version which still has AnsiString - if this is on a newer version UnicodeString then the code could lead to "strange results" since unicode string take up multiple bytes per character (depending on the encoding etc.).

Answer 3

char dum[32];   
strcpy(dum,InstList->Lines->Text.c_str());

Answer 4

Do not use char* use String or std::string instead and if you need a pointer to your string for some reason just take this from your string object.

String myString = InstList->Lines->Text;
myString.c_str();