• Namal (18/18) Feb 28 2020 Hello,
• drug (21/50) Feb 28 2020 D compiler is smart enough to say that the first use of `b` in for loop

Namal <sotis22 mail.ru> writes:

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

drug <drug2004 bk.ru> writes:

On 2/28/20 11:48 AM, 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
 
 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

D compiler is smart enough to say that the first use of `b` in for loop 
is useless. Use either this variant:
```
import std.stdio;

void main(){

  int b = 0;

  for (; b<3; b++){
    writeln(b);
  }
}
```
or this:
```
import std.stdio;

void main(){

  for (int b; b<3; b++){
    writeln(b);
  }
}
```