Python Programming Tutorial - 21: Nested Loops

In this tutorial we'll learn to use nested loops in python along with the break statement to display prime numbers as well as non prime numbers between 2 and 100.

[lorikampsnider]

Great video. Took me 20 minutes staring at the code to understand it, but eventually got it. Btw, I could understand you relatively well, but then again, I have years of IT experience dealing with Indian support. Thanks for the tutorial.

[alexanderstatan]

This was exactly what I was looking for thank you for making this video!

[retiredshitposter]

When I want the bad tutorials. I come here. Thanks!

[jorgeespinoza]

I understand the logic for all numbers except for the number 2. It appears to me 2 only evaluates to 1 in the inner loop, so 2 % 1 is obviously == 0, howeve itr is (correctly) flagged as "prime" in the output. Could someone explain to me how this happened? What am I missing here?

[sindhujadoolam]

Sir I have a doubt in the second for loop

[clearofcloud]

Very nicely done.Took some time to understand why you put flag=true in the second line there.But I get it.

[pankajptl]

m = 0
for x in range (1, 3):
for y in range (4, 6):
m = m + x + y
print (m)


please explain this program

[aafaquequreshi]

how can we recognize where we should use 'while loop' and where 'for loop'?? Is there any trick to understand that?

[retarddevil]

what does the mean (var1%var2==0) what does % do and here what does 2==0 means ?

[weezybusy]

I couldn't make out some words in this video so i didn't understand about flags and how the second loop is working. Can someone explain it to me?

[ranjan]

second loop var-1 is not working in Python 3.
If hope it should be var only..
Below program is working fine for me :

for var1 in range(2, 101):
flag=True
for var2 in range(2, var1):
if(var1%var2==0):
print(var1, "is not a prime number")
flag=False
break
if flag:
print(var1, "is a prime number")

[ayushsharma]

same program copy kara, and run kiya but output different aa raha h. help

[subhasisparija]

for var in range(1, 100):
var1=var;
c=1;
for i in range(2, var1):
if(var1%i==0):
c=2;

if c==1:
print(var);



i have used this logic gives an error "unindent does not match any outer idention level"

please help...n thanx

[cdlV]

Your program doesn't count for n-1, 7 is not being divided by 6 which works is this case because no number is divisible by a number-1. For people wanting to know what variables are being passed at each point in the nested loop. This might help make things clearer. My code is as follows: -
for x in range(2, 101): #it's 2 to 10, 1 less than the range
flag=True
for y in range(2, x):
print("x is: ", x, "\n", "y is: ", 2, "to ", x, "Y\'s value is now: ", y)
if(x%y==0):
print(x, "is not a prime number")
flag=False
break
if flag:
print(x, "is a prime number")

Thank you for the tutorial. Hit like.

[eb]

Madhur, your microphone is not working properly in this video (21) and also the next video (22)

[aafaquequreshi]

what will happen if we don't write 'break' in the program? Can anyone provide answer in details??

[robertlatta]

It said 19 is a prime number, even though it's divisible by 9 and 10!

[kannu]

for num in range(2, 10):
for i in range (2, num):
if(num%i==0):
print(num, "is not prime")
break
else:
print(num, "is a prime")
break



this is wud work as well