This is a new one for me. Visual Studio 2008 does not accept creating an array with a non-const size, but g++ (3.4.4 on cygwin) accepts it. Is Microsoft behind the standard?
Code:#include <stdlib.h> int main(int argc, char* argv[]) { int i = atoi(argv[1]); char c[i]; }
That's C99, not C++.
Thanks.
Are the languages diverging so that C may end up with features not in C++?
>> Are the languages diverging so that C may end up with features not in C++?
Only a tiny bit.
C++0x FAQ - see the comment about VLAs.
(Note that this page was last modified today, so I assume it's up-to-date.)
It's a GNU extension for C++.
cyberfish@cyberfish-desktop:/tmp$ g++ -pedantic a.cpp
a.cpp: In function ‘int main(int, char**)’:
a.cpp:5: error: ISO C++ forbids variable length array ‘c’
cyberfish@cyberfish-desktop:/tmp$ gcc -v
Using built-in specs.
Target: i486-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 4.3.3-5ubuntu4' --with-bugurl=file:///usr/share/doc/gcc-4.3/README.Bugs --enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr --enable-shared --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --enable-nls --with-gxx-include-dir=/usr/include/c++/4.3 --program-suffix=-4.3 --enable-clocale=gnu --enable-libstdcxx-debug --enable-objc-gc --enable-mpfr --enable-targets=all --with-tune=generic --enable-checking=release --build=i486-linux-gnu --host=i486-linux-gnu --target=i486-linux-gnu
Thread model: posix
gcc version 4.3.3 (Ubuntu 4.3.3-5ubuntu4)
don't think C supports that either. Mostly because whether to allocate at runtime or at compile time is not part of the standard, and so would be implimentation dependent. Some applications may not support dynamic memory allocation (its part of the libraries not the language itself). I know there are some microcontrollers where this would be an difficult issue.
try this instead -
Code:#include <stdlib.h> int main(int argc, char* argv[]){ int i = atoi(argv[1]); char* c = (char*)malloc(sizeof(char) * i); return 0; }
Last edited by abachler; 08-31-2009 at 09:15 PM.
And yet, it does. Granted C99 is needed not C89.Originally Posted by abachler
