While, If, Count Statements
Cai Gengyang
gengyangcai at gmail.com
Tue Nov 28 02:50:03 EST 2017
On Tuesday, November 28, 2017 at 6:09:17 AM UTC+8, Ned Batchelder wrote:
> On 11/27/17 7:54 AM, Cai Gengyang wrote:
> > Input :
> >
> > count = 0
> >
> > if count < 5:
> > print "Hello, I am an if statement and count is", count
> >
> > while count < 10:
> > print "Hello, I am a while and count is", count
> > count += 1
> >
> > Output :
> >
> > Hello, I am an if statement and count is 0
> > Hello, I am a while and count is 0
> > Hello, I am a while and count is 1
> > Hello, I am a while and count is 2
> > Hello, I am a while and count is 3
> > Hello, I am a while and count is 4
> > Hello, I am a while and count is 5
> > Hello, I am a while and count is 6
> > Hello, I am a while and count is 7
> > Hello, I am a while and count is 8
> > Hello, I am a while and count is 9
> >
> > The above input gives the output below. Why isn't the output instead :
> >
> > Hello, I am an if statement and count is 0
> > Hello, I am a while and count is 0
> > Hello, I am an if statement and count is 1
> > Hello, I am a while and count is 1
> > Hello, I am an if statement and count is 2
> > Hello, I am a while and count is 2
> > Hello, I am an if statement and count is 3
> > Hello, I am a while and count is 3
> > Hello, I am an if statement and count is 4
> > Hello, I am a while and count is 4
> > Hello, I am a while and count is 5
> > Hello, I am a while and count is 6
> > Hello, I am a while and count is 7
> > Hello, I am a while and count is 8
> > Hello, I am a while and count is 9
>
> It's easy to imagine that this sets up a rule that remains in effect for the
> rest of the program:
>
> â â â if count < 5:
> â â â â â â â print "Hello, I am an if statement and count is", count
>
> But that's not how Python (and most other programming languages) works.â Python
> reads statements one after another, and executes them as it encounters them.â
> When it finds the if-statement, it evaluates the condition, and if it is true
> *at that moment*, it executes the contained statements.â Then it forgets all
> about that if-statement, and moves on to the next statement.
>
> --Ned.
Sure, so how would the code look like if I want the "if" statement to be nested inside the "while" loop and give me the result :
Hello, I am an if statement and count is 0
Hello, I am a while and count is 0
Hello, I am an if statement and count is 1
Hello, I am a while and count is 1
Hello, I am an if statement and count is 2
Hello, I am a while and count is 2
Hello, I am an if statement and count is 3
Hello, I am a while and count is 3
Hello, I am an if statement and count is 4
Hello, I am a while and count is 4
Hello, I am a while and count is 5
Hello, I am a while and count is 6
Hello, I am a while and count is 7
Hello, I am a while and count is 8
Hello, I am a while and count is 9
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