variables - Precedence of arithmetic operators in Java -


i reading "programming in java deitel & deitel 7th edition" , watched precedence of operators trepidation.

the author says when there mathematical typical expression in there operators of equal precedence operation runs left right. example:

system.out.println (a + b + c - d);

in sense operation executed left right, research on internet , find "=" operator runs right left. example:

int x; x = 4 * 4 * 4% 2;

all taxes fine until ponogo investigate further , write code , occurs me this, wrote exeption:

system.out.println ((4 * 4) + (8 * 8) * (4 * 4) - 16/4);

and question this, if book says addition , subtraction have lower priority compared other operators, if add value of typical expression multiplied ?. let me explain:

when put (4 * 4) + (8 * 8) * (4 * 4) adding value of multiplication, lower precedence of operator?

another question:

if have example follows:

system.out.println (a * b * c + d + e + f * g / h);

as higher precedence operations executed first order left right, when time run higher precedence run left right well?

when value of variable assigned, operators of higher precedence associate right left?

i'll try answer references, can go whatever depth want. it's not entirely clear confusing you.

firstly, need clear on difference between assignment operators (= in examples, these include e.g. += etc) , other (binary) operators (e.g. +,-,*,% etc). assignment operators (such =) evaluate right left - i.e. work out value of on right of operator , then assign whatever on left.

for other operators, first apply operator precedence , then apply left right operation on operators equal precedence. table of precedence , discussion of available in the official tutorial. similar table (fig a.1) on p.1509 of book using, web tutorial explanation may easier understand. can summed precedence being applied expressions in brackets first, followed postfix unary operators (e.g. x++, -x), multiplicative operators (*,\,%) , additive (+,-) , lots of logical operators not directly relevant question.

finally, tutorial contains statement

when operators of equal precedence appear in same expression, rule must govern evaluated first. binary operators except assignment operators evaluated left right; assignment operators evaluated right left.

crucially, precedence left-to-right evaluation repeated, illustrated going through example step step:

(4 * 4) + (8 * 8) * (4 * 4) - 16/4 // found brackets - highest precedence. // more one, evaluate left right 16 + (8 * 8) * (4 * 4) - 16/4 16 + 64 * (4 * 4) - 16/4 16 + 64 * 16 - 16/4 //brackets finished, precedence.  found multiplicative operators //evaluate left right 16 + 1024 - 16/4 16 + 1024 - 4 //multiplicative finished, precedence.  found additive operators //evaluate left right 1040 - 4 1036 // expression evaluated. can used / assigned variable

addendum

the definitive specification evaluation of expressions in java language specification chapter 15. it's more confusing helpful @ level, include completeness. section 15.7.3 deals respecting brackets (parantheses) around expressions , operator precedence.


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