题目:
思考While循环,看看它的特点是什么?
知识点:
while循环
分析:
特点:while-loop(while 循环)。while-loop 会一直执行它下面的代码片段,直到它对应的布尔表达式为False 时才会停下来。
问题:while循环的条件总是为真时,该循环永不停止,直到天荒地老,海枯石烂。
解决:为了避免这样的问题,你需要遵循下面的规定:
1. 尽量少用while-loop,大部分时候for-loop 是更好的选择。
2. 重复检查你的while 语句,确定你测试的布尔表达式最终会变成False 。
3. 如果不确定,就在while-loop 的结尾打印出你要测试的值。看看它的变化。
代码分析:
i = 0 numbers = [] while i < 6: print("At the top i is %d" % i) numbers.append(i) i = i + 1 print("Numbers now: ", numbers) print("At the bottom i is %d" % i) print("The numbers: ") for num in numbers: print(num, end=‘\t‘)
结果:
At the top i is 0 Numbers now: [0] At the bottom i is 1 At the top i is 1 Numbers now: [0, 1] At the bottom i is 2 At the top i is 2 Numbers now: [0, 1, 2] At the bottom i is 3 At the top i is 3 Numbers now: [0, 1, 2, 3] At the bottom i is 4 At the top i is 4 Numbers now: [0, 1, 2, 3, 4] At the bottom i is 5 At the top i is 5 Numbers now: [0, 1, 2, 3, 4, 5] At the bottom i is 6 The numbers: 0 1 2 3 4 5 来自《笨办法学Python》
原文地址:https://www.cnblogs.com/brightyuxl/p/9189139.html
时间: 2024-10-03 23:17:36