Long IF statement

[pjb]

I have to compare a string value to about thirty possibilities. On way would be a long IF OR combination, something like this:
If ((!strcmp(fielda,"AAA&quot) || (!strcmp(fielda,"BBB&quot) || (!strcmp(fielda,"CCC&quot) ..........).

Is there a slicker way?

 

[Zyrenthian]

Well, it depends on the possablities you need to compare it to.

Suppose you know that it will use just the characters

ABCDEFGHIJKLMNOP

you can then do a strspn on it with that character set and if there are invalid characters you know not to process it.

Also, there exists a finite number of valid strings of which you could create special cases. This approach is too much work if it is just 30 or so strings and I would say stay with the big if condition. If that seems to look a bit nasty, you could alway move the if condition to a funciton called ValidString(char* ptr) and return if it is valid or not.

Matt

 

[pjb]

I think I might use an array to hold my values, and then spin thru the array using only one if statement. I know the values are always three characters long, so I could set the array up like this:

static char my_array[]={"AAA","BBB","CCC",......};

The loop can go like this:
for (x=0;x<sizeof(my_array)/5;x++)
{
if (!strcmp(field1,my_array[x]))
{ Do whatever
}
}

 

[rbobbitt]

To improve upon that idea a bit, you could use bsearch() to do a binary search on the array rather than a linear search.

On a side note, to get the number of elements in an array, you can do this:

sizeof array / sizeof *array

You can wrap this up in a macro:

#define ARRAY_SIZE(A) (sizeof (A) / sizeof *(A))

Beware: this doesn't work with pointers.
Russ
bobbitts@hotmail.com

http://home.earthlink.net/~bobbitts

 

[amarevu]

Hey Dude,
This is Good logic(int value = 'A' | 'A'<<8 | 'A'<<16;
), But for each and every String there is a need of doing bit operations. Instead of doing like this it is better to use if conditions using strcmp or strcasecmp. Am i right?

Amarnath Revuri.

 

[rbobbitt]

Yes, but placing the strings in an array (like in pjb's example) and doing the comparisons in a loop is easier to write and maintain.

Anyway, I doubt Zyrenthian was being serious in his example

Russ
bobbitts@hotmail.com

http://home.earthlink.net/~bobbitts

 

[hnd]

Try following:

boolean swichtval=false;

Switchwal |= (Strcmp(str1,checkstring1)=0);
Switchwal |= (Strcmp(str1,checkstring2)=0);
Switchwal |= (Strcmp(str1,checkstring3)=0);

.
.
.
if(switchval)
{
.....

If it is necessary, you could store all the strings in an array, and perform the initial checks within a loop.

hnd
hasso55@yahoo.com

 

[rbobbitt]

That's fine as long as you don't care which of the &quot;check&quot; strings str1 compares equal to.

BTW, boolean isn't a C type.
Russ
bobbitts@hotmail.com

http://home.earthlink.net/~bobbitts

 

[hnd]

@rbobitt,

Ok.
Then use
int switchval=0;


hnd
hasso55@yahoo.com