Character arrays - constant values in a constant expression

Hi, does anyone know why I can use 'sizeof()' but not 'strlen()' for defining the size of an array. I get the following error message in the picture I've attached:

Attachment 15077

Thanks in advance.

Because sizeof() is evaluated at compile time, whereas strlen() is evaluated at run-time.

Also, only C99 supports variable length arrays of the form you're using.

What you need to write in C++ is
char *asterisk = new char[ strlen(s) + 1 ];

What you need to write in C++ is:
std::string asterisk;