How can I create a variable of type "voidPtr" which points to a string using the LIBPOINTER function in MATLAB?

I have a function in a generic library which takes a string as input. The function, however, expects a void pointer. When I try to call the function using the CALLLIB function with a string as input, I get the following error:

 ??? Error using ==> calllib

 Array must be numeric or logical or a pointer to one.

Answer 1

[MathWorks Support Team]

This enhancement has been incorporated into the documentation as of MATLAB 7.2 (R2006a). For previous product releases, read below for any possible workarounds:

In C, characters are represented as unsigned 8-bit integers. In order to create a variable of type "voidPtr" containing a string, the string must first be cast to one of this numeric type as in the following code:

p=libpointer('voidPtr',[ uint8('this is a string') 0]);

The data in the pointer can then be accessed:

p.value

char(p.value)

To call a function that takes a voidPtr as input, use the following syntax:

foo(uint8(str));

where "foo" is the name of your function and "str" is the string.