preset counter variable in a for loop --> 'has no effect' Error

[Namal via Digitalmars-d-learn]

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

Same works perfectly fine in C++

#include <iostream>

int main(){
 int i = 0;

 for(i; i<3; i++)
   std::cout<<i<<'\n';
}

Please help me find what I am doing wrong. Thx