php multiple if conditions

Question

when i try to filter all these parameters php only enters in the first if conditions, ignoring all others conditions.

if($t_red<0){
    $t_red=0;
}

else if($t_red>256){
    $t_red=255;
}

else if($t_green<0){
    $t_red=0;
}

else if($t_green>256){
    $t_red=255;
}

if($t_blue<0){
    $t_red=0;
}

if($t_blue>256){
    $t_red=255;
}

if($t_red<0){
    $t_red=0;
}

`else` statements only run if the `if` is false. Also, why does each `if` have `$t_red=`? — gen_Eric, Jan 26 '11 at 21:54
what is the value of $t_red,$t_green and $t_blue? maybe you should group some of those conditions — Dalen, Jan 26 '11 at 21:54

score 7 · Answer 1 · answered Jan 26 '11 at 21:55

Probably best suited if ran through a filtering function.

function setParam($param) {
  if($param < 0) {
    $param = 0;
  } elseif($param > 256) {
    $param = 255;
  }

  return $param;
}

$t_green = setParam($t_green);
$t_red = setParam($t_red);
$t_blue = setParam($t_blue);

You could also use pass-by-reference if necessary.

score 1 · Answer 2 · answered Jan 26 '11 at 21:53

1

It's not clear what you're trying to do, but I think that you would want to remove the else before the third if statement and add an else before the sixth if statement.

answered Jan 26 '11 at 21:53

Scott Cranfill

1,046
5
13

score 0 · Answer 3 · answered Jan 26 '11 at 21:55

0

$t_red=$t_red<0?0;$t_red;
$t_red=$t_red>=256?255;$t_red;


//are you sure you're modifying t_red here? and not t_green?
$t_red=$t_green<0?0;$t_red;
$t_red=$t_green>=256?255;$t_red;

//are you sure you're modifying t_red here? and not t_blue?
$t_red=$t_blue<0?0;$t_red;
$t_red=$t_blue>=256?255;$t_red;

answered Jan 26 '11 at 21:55

FatherStorm

7,133
1
21
27

you mean to put : in a few places e.g. $t_red=$t_red<0?0:$t_red; – Foo Bah Jan 29 '11 at 04:04

score 0 · Answer 4 · answered Jan 26 '11 at 21:58

a successfully met condition of an if (or following else if) statement will ignore all else if/else statements that immediately follow it, but the if statements afterwards are executing - You can verify this by adding echo statement to each one . Could it perhaps be because all your variable assignments are for $t_red so no action is taken on $t_green or $t_blue?

score 0 · Answer 5 · answered Jan 26 '11 at 22:25

if($t_red < 0)
{
    $t_red = 0;
}
else if($t_red > 255) //Original won't catch it if it is == to 256, have to do either >= 256 or > 255
{
    $t_red = 255;
}

if($t_green < 0)
{
    $t_green = 0;
}
else if($t_green > 255)
{
    $t_green = 255;
}

if($t_blue < 0)
{
    $t_blue = 0;
}
else if($t_blue > 255)
{
    $t_blue = 255;
}

Andrew Sledge's answer is the best though, but I did correct the fact that it would miss correcting the value if it was == to 256, which wouldn't be caught by just $var > 256, and thus would be in error if the value has to be between 0 and 255.

php multiple if conditions

5 Answers5

Linked

Related