Question on ifs

Question

Hi,

I have the following code:

     boolean Short = x();
    boolean Long = y();       
    boolean Longer = z();

    if (Short )
        return "abc";

    if (Long)
        return "def";

    if (Longer) 
        return "ghi";        

The three bool methods (x, y, z) all do maths on value. I need an additional if statement to return the number from if the above 3 ifs are not evaluated to true. How could this be done and are there any redundant ifs? Also, what do I need to know about precedence with ifs? My name says "dotnet" but I am equally a programmer in Java (I've spent time trying to pick it up as much as .NET).

Thanks

Answer 1

It's fine, but you do not need another if:

boolean Short = x();
boolean Long = y();       
boolean Longer = z();

if (Short )
    return "abc";

if (Long)
    return "def";

if (Longer) 
    return "ghi"; 

return "none of the above";

The if statements will evaluate in order, once one of them is true, the return statement will end execution within the method, so nothing after it will be evaluated.

If none of them are true, the last return will end execution.

You could substitute the variables with the calls themselves if you do not need to evaluate y() and z() when x() is true, nor z() if y() is true:

if (x())
    return "abc";

if (y())
    return "def";

if (z()) 
    return "ghi"; 

return "none of the above";

Answer 2

Just put:

boolean Short = x();
boolean Long = y();       
boolean Longer = z();

if (Short )
    return "abc";

if (Long)
    return "def";

if (Longer) 
    return "ghi";

return "xyz";

Answer 3

Hm.. Probably this

if (x())
    return "abc";

if (y())
    return "def";

if (z()) 
    return "ghi"; 
return "smt"; 

Answer 4

In order to return a value for all three being false, simply do this :

if(!Long && !Short && !Longer)
   return "Whatever you are returning"

Answer 5

There are no redundant if's. You just need an extra return in case none of the three conditions evaluate to true. You can also add else clauses if you want.

boolean Short = x();
boolean Long = y();       
boolean Longer = z();

if (Short )
    return "abc";
else if (Long)
    return "def";
else if (Longer) 
    return "ghi";
else
    return "something else";

Or, if the methods x(), y(), z() have no side effects:

if (x())
    return "abc";
else if (y())
    return "def";
else if (z()) 
    return "ghi";
else
    return "something else";

Also, you can use the ? operator for a more compact, but perhaps more cryptic syntax:

return x()? "abc" :
       y()? "def" :
       z()? "ghi" :
       "something else";

But ifs are probably more readable than this :-)