非常详细的解释一下下面的代码 function createClosure() { let called = false; return function() { if (called) { return; } called = true; // 闭包内部的代码 console.log('闭包被调用了'); };}const closure = createClosure();closure(); // 输出:闭包被调用了closure(); // 没有输出
时间: 2023-06-20 08:07:05 浏览: 50
这段代码定义了一个叫做 `createClosure` 的函数,该函数返回一个闭包函数。闭包函数内部有一个变量 `called`,它的初始值为 `false`。
当我们调用闭包函数时,它首先会检查 `called` 是否为 `true`,如果是,则直接返回,不执行闭包内部的代码。否则,将 `called` 的值修改为 `true`,表示闭包已经被调用过了,并且执行闭包内部的代码,即输出字符串 `闭包被调用了`。
最后,我们通过调用 `createClosure()` 函数返回闭包函数,并将其赋值给变量 `closure`。我们连续调用 `closure()` 两次,第一次输出了字符串 `闭包被调用了`,第二次没有输出任何东西,这是因为在第一次调用闭包函数时,`called` 已经被修改为 `true`,所以第二次调用时直接返回了。这就是闭包的一个典型用法,能够保留函数内部的状态,供以后的调用使用。
相关问题
Write a function called calculate_slope which return the slope of a linear equation
Sure, I can help with that! Here's a Python function that calculates the slope of a linear equation based on two points:
```python
def calculate_slope(x1, y1, x2, y2):
slope = (y2 - y1) / (x2 - x1)
return slope
```
You can call this function by passing in the x and y coordinates of two points on the line. The function will return the slope of the line. Let me know if you have any other questions!
use C program Check whether two words are Anagrams. If they are, return 1, otherwise return 0. If two words contain the same letters in different order, they are called anagram. For example, "silent" and "listen" are anagram. Input There are two lines of input, corresponding to two words. Output If two words are anagrams, output true; otherwise, output false.
Certainly! Here's a C program to check whether two words are anagrams:
```c
#include <stdio.h>
#include <string.h>
int main() {
char str1[100], str2[100];
int len1, len2, i, j, freq1[26] = {0}, freq2[26] = {0};
printf("Enter first word: ");
scanf("%s", str1);
printf("Enter second word: ");
scanf("%s", str2);
len1 = strlen(str1);
len2 = strlen(str2);
if(len1 != len2) {
printf("false\n");
return 0;
}
for(i=0; i<len1; i++) {
freq1[str1[i]-'a']++;
freq2[str2[i]-'a']++;
}
for(i=0; i<26; i++) {
if(freq1[i] != freq2[i]) {
printf("false\n");
return 0;
}
}
printf("true\n");
return 0;
}
```
The program first declares two character arrays `str1` and `str2` of size 100 to store the user input. It prompts the user to enter the two words using the `printf()` and `scanf()` functions.
The program then computes the length of each word using the `strlen()` function and compares the lengths. If the lengths are not equal, the program prints "false" and exits.
If the lengths are equal, the program initializes two arrays `freq1` and `freq2` of size 26 to keep track of the frequency of each letter in each word. It then loops through each character in both words and increments the corresponding frequency array.
Finally, the program loops through the frequency arrays and checks if the frequencies of each letter in both words are equal. If they are not equal, the program prints "false". Otherwise, it prints "true".
I hope this helps! Let me know if you have any questions.