Re: else ladders practice

On 2024-10-31, fir wrote:

Dan Purgert wrote:

On 2024-10-31, fir wrote:

somethins i got such pices of code like
>
if(n==1) {/*something/}
if(n==2) {/*something/}
if(n==3) {/*something/}
if(n==4) {/*something/}
if(n==5) {/*something/}
>
technically i would need to add elses - but the question is if to do that
>
do teh code has really chance to be slower without else (except some
very prmitive compilers) ??

>
In the above, all conditionals are always checked -- that is the truth
of a previous conditional statement has no bearing on subsequent tests.
This leads to the potential of tests going off in directions you hadn't
necessarily anticipated.
>
However, 'if..elseif..else' will only check subsequent conditionals if
the prior statements were false.  So for the case that "n=2", you're
only ever testing the two cases "if (n==1)" (which is false) and
"elseif(n==2)".  The computer just skips to the end of the set of
statements.
>
>
Given this MWE (my own terrible code aside ;) ):
>
   int main(){
     int n=0;
     printf ("all if, n=%u\n",n);
     if (n==0) { printf ("n: %u\n",n); n++;}
     if (n==1) { printf ("n: %u\n",n); n++;}
     if (n==2) { printf ("n: %u\n",n); n++;}
     if (n==3) { printf ("n: %u\n",n); n++;}
     if (n==4) { printf ("n: %u\n",n); n++;}
     printf ("all if completed, n=%u\n",n);
>
     n=3;
     printf ("with else if, n=%u\n",n);
     if (n==0) { printf ("n: %u\n",n); n++;}
     else if (n==1) { printf ("n: %u\n",n); n++;}
     else if (n==2) { printf ("n: %u\n",n); n++;}
     else if (n==3) { printf ("n: %u\n",n); n++;}
     else { printf ("n: %u\n",n); n++;}
     printf ("with else if completed, n=%u\n",n);
   }
>
>
You'll get the output:
>
all if, n=0
n: 0
n: 1
n: 2
n: 3
n: 4
all if completed, n=5
with else if, n=3
n: 3
with else if completed, n=4
>
HTH :)
>

i not modify n in those {} blocks so this example is not much relevant

I'm using that as a simplified case to force the issue.  "n" could be
modified anywhere, just so long as it is "between" any two of the test
cases being checked.

>
my quiestion is more liek what is a metter of beter style

If it is a series of related conditions, then "if .. else if .. else".

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