IF Statement Doesn't Work Properly - Arduino Forum

IF statement doesn’t work properly Projects Programming afek May 29, 2021, 9:35pm 1

For some reason I always get that the first condition is true and it prints waterB = 389 when I want waterA = 89

3c06b91b8b5432e4e2c76ef6fe6e1303491×679 9.9 KB

UKHeliBob May 29, 2021, 9:36pm 2

Your post was MOVED to it's current location as it is more suitable.

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UKHeliBob May 29, 2021, 9:39pm 3

You have the syntax of you range based if statements wrong. It should be of the form

if (variable >= 123 && variable <= 345) { //conditional code here } anon73444976 May 29, 2021, 9:41pm 4

"IF statement doesn’t work properly"

Try to imagine how many posts there would be here if that statement were really true.

Occam's Razor suggests that how you wrote the "if" is at fault.

Bob beat me to it.

afek May 29, 2021, 9:48pm 5

Thank you so much

I just dont get why it didnt count as error

anon73444976 May 29, 2021, 9:49pm 6 afek:

I just dont get why it didnt count as error

Because it is perfectly syntactically correct.

"My hovercraft is full of eels"

UKHeliBob May 29, 2021, 10:09pm 7 afek:

I just dont get why it didnt count as error

You get a warning if you have them turned on in the IDE preferences, which you probably should have, but as AWOL says it is perfectly good syntax

westfw May 29, 2021, 10:21pm 8 anon73444976:

afek:

I just dont get why it didnt count as error

Because it is perfectly syntactically correct.

This is one of the disadvantages of C/C++, as a language. Lots of statements that are "obviously wrong" are in fact perfectly legal statements. In this case, you have if (0<=var<100), and the C language says that logical expressions evaluate to 0 (for false) and 1 (for true). And complex logical expressions obey a defined order of operations. So... 0<=var evaluates to either 0 or 1, and then both 0<100 and 1<100 are clearly true...

If you had turned on "More" or "All" "compiler Warnings" in the preferences dialog, you would have gotten a warning message:

warning: comparisons like 'X<=Y<=Z' do not have their mathematical meaning [-Wparentheses] 73 | if (0<=PORTB<=100) {

But it would have scrolled by quickly, not been very readable, and would probably not been noticed anyway.

gfvalvo May 29, 2021, 11:46pm 9 anon73444976:

"IF statement doesn’t work properly"

Try to imagine how many posts there would be here if that statement were really true.

Those newbies say the darnedest things. Moreover, imagine how useful the BILLIONS of lines of C / C++ code that have been written over the past 50 years would be if the 'if' statement didn't "work properly".

westfw May 30, 2021, 12:06am 10 gfvalvo:

newbies say the darnedest things.

Be nice. THEIR if statement was not doing what THEY wanted it to - it was indeed not working properly. They never really implied that they thought the compiler was broken. There was a simple explanation, and it's all fine now.

system Closed September 27, 2021, 12:07am 11

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