preset counter variable in a for loop

[mipri]

On Friday, 28 February 2020 at 12:44:52 UTC, Namal wrote:
> Hello,
>
> I don't understand why this simple code causes a compiler 
> error..
>
> import std.stdio;
>
> void main(){
>
>  int b = 0;
>
>  for (b; b<3; b++){
>    writeln(b);		
>  }
> }
>
> $Error: b has no effect

Well, that's the error. b has no effect, so there's
no need for it, and it's likely written in error. It
has no effect in C++ either, and you may get a warning:

example.cc: In function 'int main()':
example.cc:7:8: warning: statement has no effect [-Wunused-value]
   for (b; b<3; b++){