我有一个函数,它记录函数在素数数组中查找目标数字所需的函数调用次数。我目前使用在全局范围内声明的计数器。如何将此计数器作为静态变量放入函数作用域中,以便每次调用函数时它都不会改变?
let primes = [2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97]
let counter = 1
function findPrime(arr, target){
let guess = arr[Math.floor(arr.length/2)]
if (guess > target){
arr = arr.splice(0, arr.length/2)
counter ++
findPrime(arr,target)
}else if (guess < target){
arr = arr.slice(arr.length/2)
counter ++ || 1
findPrime(arr,target)
}else{
console.log('guesses taken: ' + counter)
console.log('target is: ' + guess)
}
}
findPrime(primes, 2)
最佳答案
您使函数返回更新的计数器,因此您不必全局维护它;请参阅 ***
评论:
let primes = [2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97]
function findPrime(arr, target, counter) { // ***
if (typeof counter === "undefined") { // ***
counter = 1; // ***
} // ***
let guess = arr[Math.floor(arr.length / 2)]
if (guess > target) {
arr = arr.splice(0, arr.length / 2)
return findPrime(arr, target, counter + 1) // ***
} else if (guess < target) {
arr = arr.slice(arr.length / 2)
return findPrime(arr, target, counter + 1) // ***
} else {
console.log('guesses taken: ' + counter)
console.log('target is: ' + guess)
return counter;
}
}
findPrime(primes, 2)
一般来说,递归函数接受并返回允许它们跟踪和控制递归的信息。虽然您可以通过关闭非全局变量来完成此操作,但这并不是通常的做法(尽管也有异常(exception))。
关于javascript - 在递归函数中用静态变量替换全局变量,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/41808902/