The if Statement Solutions - D Programming Language

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# The if Statement Solutions

#### The if Statement Dersi Problem Çözümleri

1. The statement `writeln("Washing the plate")` is written indented as if to be within the `else` scope. However, because the scope of that `else` is not written with curly brackets, only the `writeln("Eating pie")` statement is actually inside the scope of that `else`.

   Since whitespaces are not important in D programs, the plate statement is actually an independent statement within `main()` and is executed unconditionally. It confuses the reader as well because of having been indented more than usual. If the plate statement must really be within the `else` scope, there must be curly brackets around that scope:

       import std.stdio;

       void main() {
           bool existsLemonade = true;

           if (existsLemonade) {
               writeln("Drinking lemonade");
               writeln("Washing the cup");

           } else {
               writeln("Eating pie");
               writeln("Washing the plate");
           }
       }

2. We can come up with more than one design for the conditions of this game. I will show two examples. In the first one, we apply the information directly from the exercise:

       import std.stdio;

       void main() {
           write("What is the value of the die? ");
           int die;
           readf(" %s", &die);

           if (die == 1) {
               writeln("You won");

           } else if (die == 2) {
               writeln("You won");

           } else if (die == 3) {
               writeln("You won");

           } else if (die == 4) {
               writeln("I won");

           } else if (die == 5) {
               writeln("I won");

           } else if (die == 6) {
               writeln("I won");

           } else {
               writeln("ERROR: ", die, " is invalid");
           }
       }

   Unfortunately, that program has many repetitions. We can achieve the same result by other designs. Here is one:

       import std.stdio;

       void main() {
           write("What is the value of the die? ");
           int die;
           readf(" %s", &die);

           if ((die == 1) || (die == 2) || (die == 3)) {
               writeln("You won");

           } else if ((die == 4) || (die == 5) || (die == 6)) {
               writeln("I won");

           } else {
               writeln("ERROR: ", die, " is invalid");
           }
       }

3. The previous designs cannot be used in this case. It is not practical to type 1000 different values in a program and expect them all be correct or readable. For that reason, it is better to determine whether the value of the die is within a range:

           if ((die >= 1) && (die <= 500))

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