Python Loops
Python is a powerful and popular programming language that is used by many programmers around the world. It is a versatile language that has a wide range of applications, from web development to data analytics. One of the most important features of Python is the ability to use loops, which allow you to execute a sequence of instructions multiple times. In this article, we will explore the different types of loops in Python.
For Loops
The for loop is used to iterate over a sequence of values. You can use a for loop to iterate over a range of values, a list, a tuple or even a dictionary:
“`python
# iterating over a range of values
for i in range(10):
print(i)
# iterating over a list
fruits = [“apple”, “banana”, “cherry”]
for fruit in fruits:
print(fruit)
# iterating over a tuple
my_tuple = (“apple”, “banana”, “cherry”)
for item in my_tuple:
print(item)
# iterating over a dictionary
my_dict = {“name”: “John”, “age”: 30, “city”: “New York”}
for key, value in my_dict.items():
print(key, value)
“`
The syntax of the for loop is as follows:
“`python
for variable in sequence:
# do something
“`
The variable
is used to store each value from the sequence
that the loop is iterating over.
While Loops
The while loop is used to execute a block of code as long as a condition is true:
“`python
i = 0
while i < 5:
print(i)
i += 1
```
The while loop will continue to execute until the condition i < 5
is false. It is important to ensure that the condition will become false at some point, otherwise the loop will continue indefinitely and may cause your program to crash.
Break and Continue Statements
The break statement is used to exit a loop prematurely:
```python
fruits = ["apple", "banana", "cherry"]
for fruit in fruits:
if fruit == "banana":
break
print(fruit)
```
The output of this code will be:
```
apple
```
The continue statement is used to skip over an iteration of a loop:
```python
fruits = ["apple", "banana", "cherry"]
for fruit in fruits:
if fruit == "banana":
continue
print(fruit)
```
The output of this code will be:
```
apple
cherry
```
Nested Loops
You can also use loops within other loops to create nested loops:
```python
for i in range(3):
for j in range(2):
print(i, j)
```
The output of this code will be:
```
0 0
0 1
1 0
1 1
2 0
2 1
```
The outer loop executes three times, and for each iteration, the inner loop executes twice.
Conclusion
Loops are an important construct in Python programming, allowing you to execute a sequence of instructions multiple times. In this article, we explored the different types of loops in Python, including for loops, while loops, break and continue statements, and nested loops. With these tools, you can create powerful and flexible programs in Python.