Nested While loop in Python.

Question

Hi!

I am a beginner in python programming. I wrote the following program but it doesn't execute as I want it to. Here is the code:

b=0
x=0
while b<=10:
    print 'here is the outer loop\n',b,
    while x<=15:
        k=p[x]
        print'here is the inner loop\n',x,
        x=x+1
    b=b+1

can somebody help me?? I will be grateful indeed! Regards, Gillani

Answer 1

Not sure what your problem is, maybe you want to put that x=0 right before the inner loop ?

Your whole code doesn't look remotely like Python code ... loops like that are better done like this:

for b in range(0,11):
    print 'here is the outer loop',b
    for x in range(0, 16):
        #k=p[x]
        print 'here is the inner loop',x

Answer 2

Running your code I'm get an error if "'p' is not defind" which means you are trying to use the the array p before anything is in it.

Removing that that line lets the code run with output of

here is the outer loop
0 here is the inner loop
0 here is the inner loop
1 here is the inner loop
2 here is the inner loop
3 here is the inner loop
4 here is the inner loop
5 here is the inner loop
6 here is the inner loop
7 here is the inner loop
8 here is the inner loop
9 here is the inner loop
10 here is the inner loop
11 here is the inner loop
12 here is the inner loop
13 here is the inner loop
14 here is the inner loop
15 here is the outer loop
1 here is the outer loop
2 here is the outer loop
3 here is the outer loop
4 here is the outer loop
5 here is the outer loop
6 here is the outer loop
7 here is the outer loop
8 here is the outer loop
9 here is the outer loop
10
>>>

Answer 3

Because you defined the x outside of the outer while loop its scope is also outside of the outer loop and it does not get reset after each outer loop.

To fix this move the defixition of x inside the outer loop:

b = 0
while b <= 10:
  x = 0
  print b
  while x <= 15:
    print x
    x += 1
  b += 1

a simpler way with simple bounds such as this is to use for loops:

for b in range(11):
  print b
  for x in range(16):
   print x