if else语句的编写方法

Question

An if-else statement can be written using ternary operator for eg

output = (val>val2) ? "Condition is true" : "Condition is false";

Now consider

if(condition1){
   //do something
}else if(condition2){
   //do something 
}else if(condition3){
  //do something
}

How to write above code using ternary operator ?

Answer 1

output = (condition1) ? 
          "First Case" : ((condition2) ?
          "Second Case" : ( (condition3) ? 
          "Third Case") : (...));

But keep in mind that in case, the number of conditions become more than 3, it will be a maintenance nightmare.

Answer 2

尝试这个。

(a?w:(b?x:(c?y:z)))

Answer 3

Something in expanded form like this:

X outputfn( ... )
{
  if(c1)      { return A; }
  else if(c2) { return B; }
  else        { return C; }
}

output = outputfn(...);

Can be translated into

output = (c1)?A:((c2)?B:C);

But its pretty unreadable.

So I'd recommened extracting it into a function and using the function instead.

Answer 4

I think i get it. You'll want something like:

output = (val>val3)?"First Case":(val>val2)?"Second Case":"Default Case";

You simply put subsequent ifs in the right-most clause of the expression. Note that there will always be a default case at the end.

Answer 5

Sure.

What you're trying to write is a ternary operator as an if else statement.

Well, let's logically deduce this.

output = (val>val2) ? "Code here when condition is true" : "Code here when condition is false";

What we're saying is the following

if(val > val2)
{
    //code here when condition is true;
}
else
{
  //code here when condition is false;
}

That's it!

Happy Coding! ;)

Answer 6

I would format it this way:

int result = condition1 ? 1
  : condition2 ? 2
  : condition3 ? 3
  : -1;

But I concur with other posters that nested ternary operators can be difficult to understand.

Answer 7

Why? What you've written is perfectly clear, and using the ternary operator won't change the generated code.

Answer 8

output = (condition1) ? "Condition1 is true" : ((condition2) ?
      "Condition2 is true" : ( (condition3) ? 
      "Condition3 is true" : " all Condition are false"));