Python While Loop

Python WhileViews 1165

For , If and While are the primitive compound statements/loops in  Python. In this tutorial, we will be covering only the Python while statement.

Python While Loop:

Python while loop is used to execute a set of statements as long as the condition is true. The below code prints the numbers from 1 to 10.

```a=1
while(a<=10):
print(a)
a+=1
print("Numbers 1 to 10 are printed")```

The above code works as below:

• Initializing variable a to 1
• While statement checks if the variable ‘a’ is less than or equal to 10
• If the condition is True, ‘a’ will be incremented by 1.
• When the last line has encountered, the condition of the while statement will be tested again.
• So the above code prints all the numbers from 1 to 10.
• When ‘a’ becomes 11, the condition becomes false and the loop will be exited.
• Whatever the statement was written outside the while loop will be executed.

Infinite loop:

We have to be careful about the infinite loop while using the Python ‘while’ statement. In case, we forgot to increment the variable ‘a’, it will result in an infinite loop.

```a=1
while(a<=10):
print(a)
print("Numbers 1 to 10 are printed")```

Python While and ELSE:

With the else statement we can run a block of code once when the condition given in the while statement becomes false.

```a=11
while(a<=10):
print(a)
a+=1
else:
print("a is greater than 10")```

Looping through Lists:

We can loop through lists, strings, and tuples using the while loop.

```l=[8,9,1,4,5]
length=len(l)
i=0  # since the index starts with zero
while(i<length):
print(l[i])
i+=1```

IF inside while loop:

We can also use the IF loop inside the while loop. The below code is to print the even numbers from 1 to 10.

```a=1
while(a<=10):
if a%2==0:
print(a)
a+=1```

You can modify the above code to print the odd numbers. Try more examples on while loops.

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