Convert String to Char*

[yeshello54]

Hey all. I have a small problem. I have a string called hexed. inside hexed for example is the string "003eb". I need to be able to convert this string into a char* because i have a predefined function that converts hexadecimal to decimal but its parameter that needs to be passed to it is a char *. I have been looking into a few things and Im just a little confused on how to implement it.

[Banfa]

You can't convert string to char *. You can convert string to const char * using the method string::c_str.

To do what you want you would need to copy the string to an array of char of an appropriate length using strcpy and string::c_str, call your function then assign the result back to your string.

It may be easier or at least produce cleaner code to re-write (or write an overload for) you function that operates directly on a string.

[Studlyami]

I have used this to assign a CString to a char *.

char* = (char *) (LPCTSTR)CString;

I don't know if that will help you or not.

[Banfa]

Since the op is planning on writing data to that pointer that would be a really bad idea. You have cast away the constness of a pointer, always a disaster waiting to happen.

However mentioning CString if you happen to be using MFC and CString then you can call the method GetBuffer which returns a char * and allows you to specify the size of the buffer that the returned pointer points to (not forgetting to call ReleaseBuffer once finished)

[Studlyami]

I didn't see where he stated that he was going to write to it, but yeah is definitely something to look out for and I should have stated that. If the function only reads items in the char* it should work fine, but it isn't safe. Thanks for the tip about the GetBuffer, I'll have to try it out.

[weaknessforcats]

char* = (char *) (LPCTSTR)CString;

Be careful of this code. CString be either a char* string or a wchar_t* string. And you can't tell which.

Once you start using TCHAR mappings, like LPCTSTR, then you can no longer use the natives types directly. Everything must now be TCHAR.

The char* would become a PTCHAR.