easy if / else question...

[TheMoonwalker]

Hi

I've got comparable code:

if (strstr(string, "Statement1")
	function1;
if (strstr(string, "Statement2")
	function2;
if (strstr(string, "Statement3")
	function3;
if (strstr(string, "Statement4")
	function4;

Problem: I need a default case... I could solve it with a flag like this:

if (strstr(string, "Statement1")
{
	function1;
	flag=TRUE;
}
if (strstr(string, "Statement2")
{
	function2;
	flag=TRUE;
}

....

if(!flag)
{
	fuction_default;
}

or maybe like this

if (strstr(string, "Statement1")
{
	function1;
}
else
{
	if (strstr(string, "Statement2")
	{
		function2;
	}
	else
	{
		if (strstr(string, "Statement3")
		{
			function3;
		}
		else
		{
			if (strstr(string, "Statement4")
			{
				function4;
			}
			else
			{
				fuction_default;			
			}
		}
	}
}

??

I dont think its the best way... I suppose that a "switch - case statement" is unfortunately not possible because I need to search the string for many different char-strings...
How would you solve this problem?

thx in advance

[LJHW]

I'd put the search in a void return function

void evaluate( const string & str )
{
  if (strstr(string, "Statement1")
  {
    function1;
    return;
  }
  if (strstr(string, "Statement2")
  {
    function2;
    return;
  }
  ...
  ...

  fuction_default();
}

It might be more OO to use a class though.
Derive all the functions from an abstract base function interface.
Have a container class that holds base function pointers with associated strings eg. statement1 with function1.
The container class can then have methods like add_function(statement1,function1) and add_default(function_default).
Finally a call to the conatiner class with a string will evaluate the correct function.
The controller can be responsible for destroying the functions.
"strstr" can be implemented within the controller.
The benefit of this is that new function/string pairs can be added easily and dynamically.
Also the complexity is wrapped up for client code eg.

  // At start-up
  Controller C;
  C.add_function("Statement1",new Function1());
  C.add_function("Statement2",new Function2());
  C.add_function("Statement3",new Function3());
  ...
  ...
  C.add_default(new DefaultFunction1());

  // When the call is needed
  C.evaluate( RuntimeString );

Cheers,
ljhw

[j0nas]

I would do:

if (strstr(str, "item1"))
    ; // do something
else if (strstr(str, "item2"))
    ; // do something
else if (strstr(str, "item3"))
    ; // do something
else if (strstr(str, "item3"))
    ; // do something
else if (strstr(str, "item4"))
    ; // do something
else if (strstr(str, "item5"))
    ; // do something
else {
    // catch all other casees here
}

[TheMoonwalker]

Thank you both for your answers... I did it exactly like j0nas said and it works fine!!


Greetz