更改for循环中的迭代次数 [英] Changing the number of iterations in a for loop

问题描述

  loopcount = 3 
我在范围内（1，loopcount）
 somestring ='7'
 newcount = int（somestring）
 loopcount = newcount 
  

所以我想要的是修改'内部'循环的范围。

我写了这个代码，期待for循环的范围会改变到（1,7）在第一个循环，但它没有发生。

相反，不管我输入什么号码，它只运行2次。 （我想6次..在这种情况下）

我检查使用打印这样的值：

<$ p （1，loopcount）
print loopcount
somestring ='7'
newcount = int（somestring）$ p $ loopcount = 3

loopcount = newcount
print loopcount
#output：
3
7
7
7


有什么不对？这个数字已经被改变了。

我的思路在哪里错了？

解决方案

范围是根据 loopcount 在被调用的时候创建的 - 任何发生在后面的loopcount都是不相关的。你可能想要的是一个while语句：

  loopcount = 3 
 i = 1 
 while I< loopcount：
 somestring ='7'
 loopcount = int（somestring）
i + = 1 
  

在 i < loopcount 为true，如果为true，则运行它所包含的语句。在这种情况下，每次通过循环时，i都增加1.由于第一次循环计数设置为7，循环将运行六次，对于i = 1,2,3,4,5和6 。

一旦条件为假，当 i = 7 时，while循环停止运行。

（我不知道你的实际用例是什么，但你可能不需要分配newcount，所以我删除了它）。

I have code like this:

loopcount = 3
for i in range(1, loopcount)
   somestring = '7'
   newcount = int(somestring)
   loopcount = newcount

so what I want is to modify the range of the for 'inside' the loop.

I wrote this code expecting the range of the for loop would change to (1,7) during the first loop, but it didn't happen.

Instead, no matter what number I put in, it only runs 2 times. (I want 6 times.. in this case)

I checked the value using print like this:

    loopcount = 3
    for i in range(1, loopcount)
       print loopcount
       somestring = '7'
       newcount = int(somestring)
       loopcount = newcount
       print loopcount
#output:
3
7
7
7

What is wrong? the number has been changed.

Where is my thinking wrong?

解决方案

The range is created based on the value of loopcount at the time it is called--anything that happens to loopcount afterwards is irrelevant. What you probably want is a while statement:

loopcount = 3
i = 1
while i < loopcount:
    somestring = '7'
    loopcount = int(somestring)
    i += 1

The while tests that the condition i < loopcount is true, and if true, if runs the statements that it contains. In this case, on each pass through the loop, i is increased by 1. Since loopcount is set to 7 on the first time through, the loop will run six times, for i = 1,2,3,4,5 and 6.

Once the condition is false, when i = 7, the while loop ceases to run.

(I don't know what your actual use case is, but you may not need to assign newcount, so I removed that).

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