D compilatore (Digital Mars D Compiler) gettando errore

Question

Sono completamente nuovo a D (provenienti da js) e stavo cercando di lavorare attraverso il tutorial, ma ho ottenuto bloccato:

mia D:

/** Returns: argument times two */ 
int twice(int x) { return x+x; } 

/** for example */ 
unittest { 
    assert (twice(-1) == -2); 
    assert (twice(2) == 4); 
} 

L'errore:

zxcv@human6:~$ dmd hello.d 
/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/crt1.o: In function `_start': 
(.text+0x20): undefined reference to `main' 
collect2: error: ld returned 1 exit status 
--- errorlevel 1 

informazioni sull'impianto:

uname -a: 

Linux human6 3.13.0-19-generiC#40-Ubuntu SMP Mon Mar 24 02:36:06 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux 


dmd version: 

dmd_2.065.0-0_amd64.deb 

gcc -v (because it's in the error): 
Using built-in specs. 
COLLECT_GCC=gcc 
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/4.8/lto-wrapper 
Target: x86_64-linux-gnu 
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 4.8.2-19ubuntu1' --with-bugurl=file:///usr/share/doc/gcc-4.8/README.Bugs --enable-languages=c,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-4.8 --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.8 --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --enable-gnu-unique-object --disable-libmudflap --enable-plugin --with-system-zlib --disable-browser-plugin --enable-java-awt=gtk --enable-gtk-cairo --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-4.8-amd64/jre --enable-java-home --with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-4.8-amd64 --with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-4.8-amd64 --with-arch-directory=amd64 --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --enable-objc-gc --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu 
Thread model: posix 
gcc version 4.8.2 (Ubuntu 4.8.2-19ubuntu1) 

Answer 1

Ogni programma richiede un punto di ingresso (una funzione main). Aggiungi void main() {} al tuo programma, o aggiungi lo switch -main alla riga di comando del compilatore per dire al compilatore di generare una funzione main per te.