>!= PHP operator, how to write not equal to or greater than?

Question

How can I write not greater-than-or-equal-to in PHP?

Is it >!= ?

Solution 1

Isn't not greater than or equal to x the same as less than x ?

Solution 2

Oh, fun. In increasing order of complexity:

1. <
2. (a - b > 0)
3. !(a >= b)
4. !(a - b <= 0)
5. !((a > b) || (a==b))
6. !(a - b < 0) && !(a - b == 0)
7. !((a - b < 0) || (a - b == 0)) && !(!(a < b))
8. !(a - b < ((a * (1/a)-1) * (b * (1/b)-1))) && !(a - b == (a * (1/a)-1) * (b * (1/b)-1)))

Personally, I would reserve #8 for someone who really annoyed me. ;)

Solution 3

The best way to write this is

$x = 4;
$y = 6;

if($x < $y) echo "True";

// True

$x = 4;
$y = 6;

if(!($x >= $y)) echo "True";

// True

Solution 4

"not greater than or equal to" is equivalent to "strictly less than" which you write as <.

If you really wanted to say "not greater than or equal to" you could just write !(a >= b).

Solution 5

<

(less than is the same as not greater than or equal to)

View more solutions

Comments

[Beweelam]

As @John Rasch points out, @Sam is using "or", where perhaps he means "nor". @Sam, can you edit the question to read "not greater-than-or-equal-to", with hyphens, if this is what you mean? Future seekers of this answer may want to avoid confusion between or/nor.

[psx]

Was July 8th 2010 a Friday? Cause this is exactly what my brain does to me on a Friday afternoon too.

[Mike]

@Ian P: I've added one for you ;-)

[Jeff Fohl]

Perhaps this question is a good candidate for code bowling? (The more code - higher points - is the winner)

[Piskvor left the building]

@Jeff Fohl: Good grief, no! We might get a distributed, parallelized, XML-backed, synergistic proactive network architecture (which somehow involves a wooden table, and whose sole purpose is to determine if x < y). There is a site for that, but it's not SO.

[Mike]

@Jeff Fohl: Does that mean that if my code is not less than or equal to your code, you will win?

[Lucas Oman]

I'm not going to upvote you simply because no one should be rewarded for knowing the answer to this question.

[murgatroid99]

I just have to mention that #8 will break on integer values (because of integer division) and non integer values (rounding errors messing with equality).

[Richard Simões]

It is incredible that an answer to this question would garner that much reputation.

[Rab]

@murgatroid Good point about #8. (+1) I must remember to avoid that issue whenever I use it. Perhaps when adding redundant operations to slow down a process, in those cases where the users are known to be evil.

[luiscubal]

@Rab isn't sleep(1) better for that?

[ninjalj]

Well, not exactly. NaNs are supposed to be unordered.

[Rab]

@luiscubal Well yeah but that would be too much like using the "<" operator ... I mean, as long as we're making things more complicated than they need to be, let's stick to it.

[el.pescado - нет войне]

New definition of mathematical induction - if something holds for 4 and 6, it is true for all integers;)

[Lemon]

@BipedalShark, I am a bit in disbelief myself O.o

[Michael Mrozek]

I used to be against weighted reputation based on question difficulty, but this is just about the greatest example in support of it I've ever seen :)

[Helmut]

no, "not greater or equal" is NOT the same as "less than"... e.g. NULL or a string is "not greater or equal" to 1, however it is not less than 1 either!

[Lemon]

@Helmut: !(null >= 1), (null < 1), !("a" >= 1), ("a" < 1), all true on my machine.

[Helmut]

well, if ("a" < 1) returns true, what about the opposite? In any case, from the logic side, just in my opinion, it is up to interpretation how to compare a string and an integer for which one is greater. But I like your solution !(...)...

[Lemon]

@Helmut, I think you need to read up on logic... None of what you have said changes the fact that !(x >= y) === (x < y). What you're comparing and how they are compared is irrelevant, as long as x and y can be compared and the comparisons are consistent.

[Helmut]

Well, Svish, sorry but let me try again explain what I mean: you say that not >= is the same as < and say that ("a" < 1) is true. So, the opposite would be that not <= is the same as >, so ("a" > 1) should return true as well. In that case, "a" would be greater than 1 and smaller than 1 - do you call this logic?

[Lemon]

@Helmut, You're not making any sense. What you're comparing is irrelevant. If !(x >= y) is true, then (x < y) is also true. If !(x >= y) is false, then (x < y) is also false. They are equivalent. They give the same result. If they don't, you need to check the implementation of your equality and comparison operators.

[Lemon]

The opposite, would be !(x <= y) and (x > y), which are also equivalent. They would give the opposite of the previously mentioned ones, unless x and y are equal. Then they all return false. Just test it out yourself.

[Helmut]

Yes, Svish... you are right. I never said that that was wrong. But still "not greater than or equal" cannot be the same as "smaller than" from a logic side, as you cannot compare a string to an integer. This would be like, speaking in images, comparing light to sound... but of course, if you are just outcome oriented as you seem to be, you say I have to equal results so it must be true... nevermind...

[Helmut]

One example, though: a function can return either a string or an integer and you need to proof wether the returned result is not greater than 1 - how will you do this with just < or >? You have to go for !( ), haven't you?

[Lemon]

@Helmut, Dude, let it go. You're not making any sense. Data types has nothing to do with the question or my answer. And even if it did, it still wouldn't matter. You can compare a number with a string without problem, you just need a comparison function that supports both.

[Helmut]

Svish, obviously I just gave you an example in my last comment, where it does matter. Why don't you tell me if my assumption is right in that case rather than poorly saying "you make no sense"? In that example I gave you you cannot use only < or > if you want to get the right results... so? have a nice day ;)

[Lemon]

Your example isn't the same as the question, so it has no relevance. Of course, if what you're after is not greater than x, then you'll use !(y > x), but that wasn't the question. The question was not equal to or greater than x, which can be written as !(y >= x), or the equivalent y < x. Have a nice day :)

[ninjalj]

@Svish: !(y >= x) is not the same as y < x. Consider NaNs, which are supposed to be unordered, and return false in every comparison (even comparing NaNs to NaNs). Incidentally, when I tested this for my answer to this question, PHP gave the wrong answer. Testing it now, it gives the right answer.

[ninjalj]

@Helmut: you were right that !(y >= x) is not the same as y < x, but you chose the wrong example. NaNs are a perfect example, comparisons with them should always return false.

[Lemon]

@ninjalj Considering NaNs was not part of the question. If you have to deal with those, go ahead and do it another way, but for regular cases this works and is correct.

[Lemon]

What's the difference between less than and strictly less than?

[Wyatt Ward]

I have been writing C for weeks and fell into this trap -_-

[Mark K Cowan]

Would this also give a better result for NaNs, with respect to the original question (>!=)

[Steve R.]

This proved useful as there are situations in my database where the return value was null. Allowed me to assign a default value: if(!($x > 0)) {$x=40;}

[Aaron Wallentine]

According to the most common meaning, that will fail, because a value that is greater will pass the second test, since it's an or, and will therefore get through. not greater than or equal typically means not greater than AND not equal, not not greater than OR not equal. But true, it is technically ambiguous as worded. I think most people would take the first meaning though.

[Nica]

you made my day xD