Thou shalt not use any other loop-var than "i"!

tdittmar

Hi everybody,

well, the subject of this posting should be part of the Ten Commandmends for programmers - at least my boss might think it should be. Compiling one of his projects, I stumbled across a C# compiler warning, asking me whether I really wanted to assign to the same variable. Never having seen this warning before, I went to see what the compiler was complaining about - I found the following piece of code:

int i; 
if(this.morePages) 
{ 
  i = this.nextRow; 
} 
else 
{ 
  i = 0; 
} 
for (i = i; i < rows; i++)

{

...

}

I decided to leave it the way it is - you can never about the side effects...

JCM

I would not have used "i" for anything but the loop counter, and done something like

int i=0; // defined here since I don't know if i gets used after the for() loop!

for(i = ((this.morePages) ? this.nextRow : 0); i < rows; i++) { ... }

jfchickimon

WTFisWTF? The guy is trying to determine the start index for the loop. Sure, he can name the variable whatever he wants, but i works nicely. To get rid of the compiler warning, just change the loop to:

for ( ; i < rows; i++)

Better yet, use the one line of concise code that JCM provided.

Phalphalak

Declaring an additional variable does not really cost you that much. :)

for (int k=i; k<rows; k++) {
...
}

I don't care about these commandments coz often they are not applicable (2 or more loops nested). If you really want to use "i" instead then swap k and i...

tdittmar

[quote user="JCM"]

I would not have used "i" for anything but the loop counter, and done something like

int i=0; // defined here since I don't know if i gets used after the for() loop!

for(i = ((this.morePages) ? this.nextRow : 0); i < rows; i++) { ... }

[/quote]

Well, I'd not have used for in the first place, but turned it into a while loop. But anyway who am I to doubt the boss...

GoatCheez

unless i is being used later this should be:

for (int i = ((this.morePages)?this.nextRow:0); i < rows; i++)

{

  ... 
}

GoatCheez

[quote user="JCM"]

I would not have used "i" for anything but the loop counter, and done something like

int i=0; // defined here since I don't know if i gets used after the for() loop!

for(i = ((this.morePages) ? this.nextRow : 0); i < rows; i++) { ... }

[/quote]

DOH!

danielpitts

[quote user="GoatCheez"]

unless i is being used later this should be:

for (int i = ((this.morePages)?this.nextRow:0); i < rows; i++)

{

  ... 
}

[/quote]

Actually, I think it is clearer to do this.

final int startRow;

if (morePages) {
startRow = nextRow;
} else {
startRow = 0;
}

for (int i = startRow; i < rows; ++i) {
...
}

Although, from looking at just this snippet, I would probably find plenty of ways to refactor this , like nextRow is probably 0 if not morePages, so you could probably always just have i in [nextRow, rows).

Thou shalt not use any other loop-var than &quot;i&quot;!

Thou shalt not use any other loop-var than "i"!