for-loop

问题 Not sure what I'm doing wrong here; the variable newStr should just return "Hello World", but I'm getting this instead: "undefinedHello World" undefined JS function translate2(x){ var newStr; x = "Hello World"; for(i=0; i<x.length; i++) { newStr+=x.charAt(i); } console.log(newStr); } 回答1: In JavaScript, if a variable is not initialized explicitly, it will by default have undefined. That is not a string but a primitive type of the Language. You can check that by printing it var newStr; console

问题 I am new to recursion and trying to understand this code snippet. I'm studying for an exam, and this is a "reviewer" I found from Standford' CIS Education Library (From Binary Trees by Nick Parlante). I understand the concept, but when we're recursing INSIDE THE LOOP, it all blows! Please help me. Thank you. countTrees() Solution (C/C++) /* For the key values 1...numKeys, how many structurally unique binary search trees are possible that store those keys. Strategy: consider that each value

问题 I am new to recursion and trying to understand this code snippet. I'm studying for an exam, and this is a "reviewer" I found from Standford' CIS Education Library (From Binary Trees by Nick Parlante). I understand the concept, but when we're recursing INSIDE THE LOOP, it all blows! Please help me. Thank you. countTrees() Solution (C/C++) /* For the key values 1...numKeys, how many structurally unique binary search trees are possible that store those keys. Strategy: consider that each value

问题 I am working to convert this MATLAB code that generates a waveform to Python. For context this is a simulation of band excitation response from an atomic force microscope (not relevant to code error). The graph that is generated from r_vec in MATLAB is different from when I generate it in Python, am I converting the MATLAB code to Python correctly? I have attached the graph of r_vec that is plotted in MATLAB which is how it should look versus what Python generates. Here is the MATLAB code

问题 I fetch the data from the web-table but the link was not an actual row attribute link. It was a 2 rows before the attribute link. Here is my code: stack = driver.find_elements_by_xpath(".//span[@data-bind = 'text: $salableQuantityData.qty']") quant = driver.find_elements_by_xpath("//*[@class='admin__data-grid-wrap']/table/tbody/tr/td[7]/div") link = driver.find_elements_by_xpath("//*[@class='admin__data-grid-wrap']/table/tbody/tr/td[15]/a") #looping all 3 variables for stuck,quantity,links in

问题 I am a learner and new to C language. While I was creating a function which will give power of two numbers using for loop I encounter that using int declaration before loop starts and also in the loop changes the output of my program. Why is this so? Code using 'int' declaration once with correct output; # include<stdio.h> int main() { int x, y; int r = 1; int k; printf("Enter base number:"); scanf("%d", &x); printf("Enter power"); scanf("%d", &y); for (k = 1; k <= y; k++) { r = r * x; }

问题 I am a learner and new to C language. While I was creating a function which will give power of two numbers using for loop I encounter that using int declaration before loop starts and also in the loop changes the output of my program. Why is this so? Code using 'int' declaration once with correct output; # include<stdio.h> int main() { int x, y; int r = 1; int k; printf("Enter base number:"); scanf("%d", &x); printf("Enter power"); scanf("%d", &y); for (k = 1; k <= y; k++) { r = r * x; }

问题 Consider a standard for loop: for (int i = 0; i < 10; ++i) { // do something with i } I want to prevent the variable i from being modified in the body of the for loop. However, I cannot declare i as const as this makes the increment statement invalid. Is there a way to make i a const variable outside of the increment statement? 回答1: From c++20, you can use ranges::views::iota like this: for (int const i : std::views::iota(0, 10)) { std::cout << i << " "; // ok i = 42; // error } Here's a demo

问题 I'm trying to port some code from Python to R and I've come across a list comprehension I cannot fully understand. Here is a toy example analogous to the code import numpy as np theta = np.random.rand(5, 2, 2, 3) thetai = theta[0] logp = [theta[np.newaxis, ...] for theta in thetai] If I run and print the results I get: print(logp) [array([[[0.779, 0.461, 0.766], [0.245, 0.189, 0.045]]]), array([[[0.229, 0.288, 0.173], [0.011, 0.541, 0.528]]])] Ok output is a list of two arrays. What I cannot

问题 I'm trying to port some code from Python to R and I've come across a list comprehension I cannot fully understand. Here is a toy example analogous to the code import numpy as np theta = np.random.rand(5, 2, 2, 3) thetai = theta[0] logp = [theta[np.newaxis, ...] for theta in thetai] If I run and print the results I get: print(logp) [array([[[0.779, 0.461, 0.766], [0.245, 0.189, 0.045]]]), array([[[0.229, 0.288, 0.173], [0.011, 0.541, 0.528]]])] Ok output is a list of two arrays. What I cannot