怎么
while (
stack.peek() in ops &&
p(stack.peek()) >= 10
) {
str += stack.pop();
}
重写，所以.peek()每次循环运行时我都调用，但是只定义一次？
我考虑过
const peek = stack.peek();
while (
peek in ops &&
p(peek) >= 10
) {
str += stack.pop();
}
但因为我修改stack与stack.pop()while循环中，我猜的价值stack.peek()是不断变化的每一次，所以我想我必须重新定义循环内的变量，但
let peek = stack.peek();
while (
peek in ops &&
p(peek) >= 10
) {
str += stack.pop();
peek = stack.peek();
}
也似乎有点不对，所以应该像
while (
let peek = stack.peek() &&
peek in ops &&
p(peek) >= 10
) {
str += stack.pop();
}
或者
for (
let peek = stack.peek();
peek in ops && p(peek) >= 10;
peek = stack.peek()
) {
str += stack.pop();
}
考虑while (true)与一起使用break：
while (true) {
const peek = stack.peek();
if (!(peek in ops) || p(peek) < 10) break;
str += stack.pop();
}
从理论上讲，您也可以这样做：
while (
(peek => peek in ops && p(peek) >= 10)(stack.peek())
) {
str += stack.pop();
}
但这很丑。大致相当于写
function pop(stack) {
const peek = stack.peek();
return peek in ops && p(peek) >= 10;
}
while(pop(stack)) str += stack.pop();
一for环是不是一个坏主意要么，并且可以写成：
for (let peek; peek = stack.peek(), peek in ops && p(peek) >= 10; ) {
str += stack.pop();
}
再次避免了重复调用stack.peek()。
本文收集自互联网，转载请注明来源。
如有侵权，请联系 [email protected] 删除。
我来说两句