If construct displaying only else value - PHP

Question

Here is my statement:

if($row_x['xfield']==$_POST['x1'] AND $row_x['yfield']==$_POST['y'])
{
   echo "ok";
}
else {
   echo "invalid";
}

When both are not equal to each other, it must display 'invalid' else, 'ok'. But in this case it displays 'invalid' whether it is valid or not.

Any clues to why?

what output of echo $row_x['xfield']. '==' . $_POST['x1'];? — Alexander Larikov
– Alexander Larikov, Commented Sep 25, 2012 at 8:25
@LewsTherin AND and OR are able to be used in as operators, but && and || have a higher order of priority. — Fluffeh
– Fluffeh, Commented Sep 25, 2012 at 8:26
@Jean The syntax looks fine, short of funky data that you would have to validate, I simply cannot see anything that visibly stands out as wrong. — Fluffeh
– Fluffeh, Commented Sep 25, 2012 at 8:28
@Jean well if output can be anything then error can be anywhere — Alexander Larikov
– Alexander Larikov, Commented Sep 25, 2012 at 8:29

HTBR · Accepted Answer · 2012-09-25 08:51:15Z

2

You said 'when BOTH are NOT equal'... implying you would want to use '!=' instead of '==' in your comparisons. See this T/F chart for &&:

--------------
| X | && | Y |
--------------
| F | F  | F |
--------------
| F | F  | T |
--------------
| T | F  | F |
--------------
| T | T  | T |
--------------

The X statement must be true AND the Y statement must be true. In your example

$row_x['xfield']==$_POST['x1']

must be TRUE as well as

$row_x['yfield']==$_POST['y']

But if I read your question you will want to have both statements as FALSE to show 'invalid'. So you'll need to substitute '==' for '!=' in each statement.

edited Sep 25, 2012 at 8:51

answered Sep 25, 2012 at 8:28

HTBR

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4 Comments

Fluffeh Over a year ago

Using the logic in the question, if unless both conditions are met, it should drop down into the the else clause.

Viktor S. Over a year ago

His statement is correct: "When both are not equal to each other, it must display 'invalid' "

Viktor S. Over a year ago

Read his code and what he needs again. Everything is correct. You just rephrasing the same thing OP already has

HTBR Over a year ago

"When both are not equal to each other, it must display 'invalid', else 'ok'" he states, implying either an OR comparison or his && comparison inverted, right? * getting confused*

Alexander Larikov · Accepted Answer · 2012-09-25 08:32:17Z

1

Replace AND with OR and it'll show ok when at least one is equal

answered Sep 25, 2012 at 8:32

Alexander Larikov

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Comments

StaticVariable · Accepted Answer · 2012-09-25 08:49:07Z

1

its because the any of them is not true or both

you are using the &&/AND so both must be match since you are getting the else result it mean any of them is not equal or both

you can check this by below method

if($row_x['xfield']==$_POST['x1']){
   echo ' xfiekd  is = to x1';
   if($row_x['yfield']==$_POST['y']){
     echo ' yfiekd  is = to y and aslo 1 is true';
   }else{ echo 'y is false' }


}
else{
   echo ' xfiekd  is = to x1' is false;
   if($row_x['yfield']==$_POST['y']){
     echo ' yfiekd  is = to y and aslo 1 is true';
   }else{ echo 'y is false' }


}

to get in if function body on true at least one condition you need to use the || instead of the AND

difference betwen AND an OR

truth table for AND

  a    b

true  true   = true
true  false  = false
false  false = false
false  true  = false

truth table for OR

  a    b

true  true   = true
true  false  = true
false true   = true
false false  = true
true  false  = true

edited Sep 25, 2012 at 8:49

answered Sep 25, 2012 at 8:31

StaticVariable

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1 Comment

StaticVariable Over a year ago

@hayden check this now .. is it ok or should i need to elaborate more

Surace · Accepted Answer · 2012-09-25 08:35:15Z

0

if($row_x['xfield']==$_POST['x1'] OR $row_x['yfield']==$_POST['y'])
{
   echo "ok";
}
else {
   echo "invalid";
}

alternative

if($row_x['xfield']!=$_POST['x1'] AND $row_x['yfield']!=$_POST['y'])
{
   echo "ok";
}
else {
   echo "invalid";
}

answered Sep 25, 2012 at 8:35

Surace

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1 Comment

StaticVariable Over a year ago

we can not use the OR as a substitute of AND since OP wants to check both

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