How to use || and && together in one if statement

Question

I am trying to check if the firstday is equal to five or 6, in both cases if totalDays is equal to 31 then do something, for that purpose which statement is correct?

Code 1:

if (firstday > 5 || firstday > 6 && totalDays == 31){}

Code 2:

if (firstday > 5 && totalDays == 31 || firstday > 6 && totalDays == 31) { }

https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Operators/Operator_Precedence — Mahi, Nov 18 '16 at 06:39
Try to iterate your conditions in english and use `()` to group conditions. In you statement *firstday has to equal to 5 or 6, but in both case, totalDays must be 31*. So solve first part: `firstday === 5 || firstday === 6`. your second condition is `totalDays===31`. But this has to happen in case of both, so this becomes, `(firstday === 5 || firstday === 6) && totalDays===31` — Rajesh, Nov 18 '16 at 06:45

score 6 · Accepted Answer · answered Nov 18 '16 at 06:39

6

This is the correct answer:

if ((firstday == 5 || firstday == 6) && totalDays == 31){
    //Do something
}

answered Nov 18 '16 at 06:39

Thum Choon Tat

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Just a pointer, you should use `===` instead of `==` – Rajesh Nov 18 '16 at 06:48

priya_singh · Answer 2 · 2016-11-18T06:40:27.450

0

Both are wrong you need to use == operator for it.

if ((firstday == 5 || firstday == 6) && totalDays == 31){}

edited Nov 18 '16 at 06:40

answered Nov 18 '16 at 06:39

priya_singh

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You need parenthesis around the || operators – mseifert Nov 18 '16 at 06:40
ya. I just edited it. Thanks. – priya_singh Nov 18 '16 at 06:40

Ashok kumar · Answer 3 · 2016-11-18T06:48:40.523

0

if ((firstday == 5 || firstday == 6) && totalDays == 31){}

Here the expression inside the inner most parenthesis(firstday == 5 || firstday == 6) is executed first. Based on the value the remaining expression is evaluated, if the above expression return false the remaining expression is not evaluated since the false&&(true||false) anyways false.

edited Nov 18 '16 at 06:48

answered Nov 18 '16 at 06:40

Ashok kumar

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Would you bother explaining your code a bit? Just dumping it in an answer is not useful. – Angel Politis Nov 18 '16 at 06:42

score 0 · Answer 4 · answered Nov 18 '16 at 06:40

0

First condition: It returns True, if firstday is 5 OR 6.. AND TotalDays is 31.

if ((firstday == 5 || firstday == 6) && totalDays == 31){ }

answered Nov 18 '16 at 06:40

Vikrant

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score 0 · Answer 5 · edited Nov 18 '16 at 06:41

Both your logic work, but you mentioned in your question that "if the first day is equal to five or 6", so I would suggest that you use '==' instead of '>'. The latter will accept any value above 5, which does not match what you want.

Either one of the following lines will achieve your desired outcome.

if (firstday == 5 || firstday == 6 && totaldays == 31) {}

OR

if (firstday == 5 && totalDays == 31 || firstday == 6 && totalDays == 31) { }

How to use || and && together in one if statement

5 Answers5