Conditional statements (if-else):
Conditional statements are used to execute code based on certain conditions. In Python, the if-else statement is used for this purpose. The general syntax of an if-else statement is as follows:
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if condition:
# code to execute if condition is true
else:
# code to execute if condition is false
For example:
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x = 5
if x > 0:
print("x is positive")
else:
print("x is non-positive")
This code will print "x is positive" since the condition x > 0 is true.
Looping structures (for, while):
Looping structures are used to execute a block of code multiple times. In Python, there are two types of loops: the for loop and the while loop.
The for loop is used to iterate over a sequence (such as a list or tuple) and execute a block of code for each item in the sequence. The general syntax of a for loop is as follows:
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for item in sequence:
# code to execute for each item
For example:
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fruits = ["apple", "banana", "cherry"]
for fruit in fruits:
print(fruit)
This code will print each item in the list of fruits.
The while loop is used to execute a block of code as long as a certain condition is true. The general syntax of a while loop is as follows:
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while condition:
# code to execute while condition is true
For example:
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x = 1
while x < 5:
print(x)
x += 1
This code will print the numbers 1, 2, 3, and 4 since the condition x < 5 is true for these values of x.
Using lists, tuples, and dictionaries:
Lists, tuples, and dictionaries are used to store collections of data in Python.
A list is a collection of items that can be of different data types. Lists are mutable, meaning that their values can be changed after they are created. To create a list, use square brackets and separate the items with commas. For example:
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fruits = ["apple", "banana", "cherry"]
A tuple is similar to a list, but its values cannot be changed after it is created. To create a tuple, use parentheses and separate the items with commas. For example:
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fruits = ("apple", "banana", "cherry")
A dictionary is a collection of key-value pairs. Each value is associated with a unique key that can be used to access the value. To create a dictionary, use curly braces and separate the key-value pairs with commas. For example:
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ages = {"John": 25, "Mary": 30, "Bob": 35}
To access the values in a list, tuple, or dictionary, use the square bracket notation. For example:
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fruits = ["apple", "banana", "cherry"]
print(fruits[0]) # prints "apple"
ages = {"John": 25, "Mary": 30, "Bob": 35}
print(ages["Mary"]) # prints 30
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