Operator Precedence
If you don't explicitly state the order in which an expression is evaluated, they are evaluated based on the operator precedence. For example, in the statement "4+2*8", the 2 will first be multiplied by 8 and then the result will be added to 4. This is because the "*" has a higher precedence than the "+". To avoid ambiguity in reading the program, it is recommended that is statement is written as "4+(2*8)". The order of evaluation can be controlled through placement of parenthesis in the code. A table of operator precedence follows below.
1
2
3
4
5
6
7
8
9
10
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12
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14
15
16
17
18
19
20
21
22
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25
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30
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43
// The highest precedence is at the top of the list and
// the lowest is at the bottom.
// Multiplicative: * / %
// Additive: + -
// Relational: < > <= >=
// Equality: == !=
// Logical AND: &&
// Logical OR: ||
// Assignment: = += -= *= /= %=
function setup() {
createCanvas(710, 400);
background(51);
noFill();
stroke(51);
stroke(204);
for (let i = 0; i < width - 20; i += 4) {
// The 30 is added to 70 and then evaluated
// if it is greater than the current value of "i"
// For clarity, write as "if (i > (30 + 70)) {"
if (i > 30 + 70) {
line(i, 0, i, 50);
}
}
stroke(255);
// The 2 is multiplied by the 8 and the result is added to the 4
// For clarity, write as "rect(5 + (2 * 8), 0, 90, 20);"
rect(4 + 2 * 8, 52, 290, 48);
rect((4 + 2) * 8, 100, 290, 49);
stroke(153);
for (let i = 0; i < width; i += 2) {
// The relational statements are evaluated
// first, and then the logical AND statements and
// finally the logical OR. For clarity, write as:
// "if(((i > 20) && (i < 50)) || ((i > 100) && (i < width-20))) {"
if ((i > 20 && i < 50) || (i > 100 && i < width - 20)) {
line(i, 151, i, height - 1);
}
}
}
