The website is under construction.

Loops

Loops allow programmers to run the same block of code repeatedly for a certain number of times.

while loop

While loops use conditional statements to determine the end of a loop.

while loop with a counter

x=0
while(x<=10):
    print(x*2)

while loop with a user input

num=int(input("Enter a positive integer number. Press 0 to stop"))
while(num>0):
    print(num + 1)
    num=int(input("Enter a positive integer number. Press 0 to stop"))

---

for loops

• A for loop is a count-controlled loop.
• It only uses a counter to determine the end of the loop
• It iterates the loop a certain number of times

This for loop works with a sequence of data items.
Each data item is assigned to the variable after each iteration (loop).

##Example 1
for num in [1,2,10,43,5]:
    print(num)

OUTPUT:
1
2
10
43
5

##Example 2
for class_name in ["Math", "English", "Science", "History"]:
    print("Course Name: "+class_name+" for Spring 2020")

OUTPUT:
Course Name: Math for Spring 2020
Course Name: English for Spring 2020
Course Name: Science for Spring 2020
Course Name: History for Spring 2020

In the example 1 above, the for loop uses the variable num to store each value in the list after each loop.
The loop will repeat 5 times because there are 5 items in the list

1. loop 1: 1 is stored in num and prints 1
2. loop 2: 2 is stored in num and prints 2
3. loop 3: 10 is stored in num and prints 10
4. and so on......

Example 2 demonstrates storing each string into the string variable class_name and then running the print statement for each time it runs the loop.

There are 5 class names in the list so, the loop will run 5 times.

---

range function with for loop

range is a built-in function in Python, which prints out lists of numbers.
This function is used in for loops to control how many times the loop repeats.
range(start,stop, step)

print(list(range(4)))      #This line of code will output a list [0,1,2,3] excluding 4

print(list(range(1,4))) #This line of code will output a list [1,2,3] excluding 4

• To include the number 4 you will need to increase the second parameter to 5

print(list(range(1,5)))    #output: [1,2,3,4]

#Example 1
for num in range(10):
    print(str(num),end=" ")
#output: 0 1 2 3 4 5 6 7 8 9

#Example 2
print("\n") #space
for num in range (30,35):
    print(str(num),end=" ")
#output: 30 31 32 33 34

#Example 3
print("\n") #space
for num in range (20, 80, 20):
    print(str(num),end=" ")
#output: 20 40 60

#Example 4
print("\n") #space
for num in range (100, 50, -10):
    print(str(num),end=" ")
#output: 100 90 80 70 60

---

Working Program Example