Python For loop
Python for loop is used to iterate different types of data types
such as List and Tuples in sequence.
Example:
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input_list = [10,20,30,40]
for x in input_list:
print(x)
Output:
10 20 30 40
From the above example, input_list is the list contains numbers, x
is the temporary variable which is used for iteration and print(x) prints the
value of x on each iteration
Enumerate()
in Python for loop:
When dealing with iterators in for loop, we need to keep the count of iterations. This can be achieved using Enumerate() method which adds a counter to a iterable and returns it in a form of enumerate object. This enumerate object can be directly used in for loops or be converted into a list of tuples() using list() method.
Input_data = ["apple", "banana","strawberry"]
for x, y in enumerate(Input_data):
print(x)
print(y)
Output:
0 apple 1 banana 2 Strawberry
Conditional
statements within for loop:
Conditional statements if/else can be
used within for loops for the conditional based for loops.
There is few drawbacks while using the
conditional statements within for loop. We use return and continue statements
in for and while loops to overcome the drawback. Let’s check the following
example
Example:
Input_data = "rabbit"
for x,y in enumerate(Input_data):
if x == "b":
print("B available")
else:
print("B not available")
Output:
B not available B not available B available B available B not available B not available
From the above example, it is
unnecessary to print the else statement once the condition is true. The main
drawback for above code is that it consumes unwanted memory and time. To avoid
this, we use break statement which
helps to stop the looping
Example for break statement:
Input_data = ["apple", "banana", "strawberry", "mango"]
for x in Input_data:
if x == "banana":
print("My favourite is " , x)
break
else:
print("please loop again")
Output:
please loop again My favourite is banana
Opposite to break statement is continue. Instead of breaking from the
condition, it simply continues to the loop.
Example for continue statement:
x = [1,2,3,4]
for i in x:
if i == 1:
continue
print(i)
Output:
2 3 4
In above example, the continue
statement, continue the loop and will not print the value for that index.
Python While Loops:
As long as the condition is “True”,
the loop gets executed continuously.
Example:
x = 1
while x<5:
print("looping")
x += 1
Output:
looping looping looping looping
From the above example, based on the
condition at while, the loop breaks when the condition fails. If there is no
increment option, then entire loop will traverse for n number of times.
We can also use break and continue
statements in while loop similar to for loop.
