D语言嵌套If语句

import std.stdio;

int main () { 
   /* local variable definition */ 
   int a = 100; 
   int b = 200; 

   /* check the boolean condition */ 
   if( a == 100 ) { 
      /* if condition is true then check the following */ 
      if( b == 200 ) { 
         /* if condition is true then print the following */ 
         writefln("Value of a is 100 and b is 200" ); 
      } 
   } 
   writefln("Exact value of a is : %d", a ); 
   writefln("Exact value of b is : %d", b ); 

   return 0; 
}