On Oct 10, 2011, at 2:14 PM, Kevin P. Fleming wrote: > On 10/10/2011 01:10 PM, Jochen Moeller wrote: >> Hello members, >> >> In a book I found some C++ code I changed to C but then got a compiler error which I >> don't understand. See the demo listings below, C versus C++. >> >> A const variable is not accepted for the definition of an array with constant size, >> and results in an error "Variable length array is not allowed at file scope" although >> the variable is defined as const. >> >> I tried some CFLAGS, used __const__ instead, and searched the archives without success. >> >> It seems that the "const" qualifier for the C-compiler is not really constant. >> >> Can this be explained and is it possible to avoid this error with some build options >> which I'm not aware of? > > In C++, 'const int' is an actual compile-time constant. In C, it's just a non-writable variable. Not quite the same thing. > > -- > Kevin P. Fleming > Digium, Inc. | Director of Software Technologies > Jabber: kfleming@xxxxxxxxxx | SIP: kpfleming@xxxxxxxxxx | Skype: kpfleming > 445 Jan Davis Drive NW - Huntsville, AL 35806 - USA > Check us out at www.digium.com & www.asterisk.org Right! Instead, the C way of doing this is to use a preprocessor definition: #define ITEMS 8 float array[ITEMS]; You are allowed to use variable-length arrays in C99 within functions, BTW. Amittai Aviram PhD Student in Computer Science Yale University 646 483 2639 amittai.aviram@xxxxxxxx http://www.amittai.com
