Comparing Python and C++ Control Structures
Contents
Python - If Statement
Conditional execution based on a boolean expression.
# Weather-based activity recommendation
temperature = 25 # in Celsius
if temperature > 30:
print("It's hot! Go for a swim.")
elif temperature > 20:
print("Nice weather! How about a picnic?")
else:
print("It's a bit cool. Maybe stay indoors.")
# Output: Nice weather! How about a picnic?
C++ - If Statement
Conditional execution in C++ using if-else statements.
#include <iostream>
using namespace std;
int main() {
int temperature = 25; // in Celsius
if (temperature > 30) {
cout << "It's hot! Go for a swim.";
} else if (temperature > 20) {
cout << "Nice weather! How about a picnic?";
} else {
cout << "It's a bit cool. Maybe stay indoors.";
}
// Output: Nice weather! How about a picnic?
return 0;
}
Python - For Loop
Iterate over a sequence (list, tuple, string) or range of numbers.
# Calculating total calories for a meal
foods = ["rice", "chicken", "vegetables", "dessert"]
calories = [200, 300, 100, 150]
total_calories = 0
for i in range(len(foods)):
total_calories += calories[i]
print(f"{foods[i].capitalize()}: {calories[i]} calories")
print(f"Total calories: {total_calories}")
# Output:
# Rice: 200 calories
# Chicken: 300 calories
# Vegetables: 100 calories
# Dessert: 150 calories
# Total calories: 750
C++ - For Loop
Traditional for loop in C++ for iterating over a range or array.
#include <iostream>
#include <string>
#include <vector>
using namespace std;
int main() {
vector<string> foods = {"rice", "chicken", "vegetables", "dessert"};
vector<int> calories = {200, 300, 100, 150};
int total_calories = 0;
for (int i = 0; i < foods.size(); i++) {
total_calories += calories[i];
cout << foods[i] << ": " << calories[i] << " calories" << endl;
}
cout << "Total calories: " << total_calories << endl;
// Output:
// rice: 200 calories
// chicken: 300 calories
// vegetables: 100 calories
// dessert: 150 calories
// Total calories: 750
return 0;
}
Python - While Loop
Execute a block of code repeatedly while a condition is true.
# Simulating battery discharge
battery_level = 100
hours = 0
while battery_level > 0:
print(f"Hour {hours}: Battery at {battery_level}%")
battery_level -= 10
hours += 1
print("Battery depleted!")
# Output:
# Hour 0: Battery at 100%
# Hour 1: Battery at 90%
# ...
# Hour 9: Battery at 10%
# Hour 10: Battery at 0%
# Battery depleted!
C++ - While Loop
Execute a block of code repeatedly while a condition is true in C++.
#include <iostream>
using namespace std;
int main() {
int battery_level = 100;
int hours = 0;
while (battery_level > 0) {
cout << "Hour " << hours << ": Battery at " << battery_level << "%" << endl;
battery_level -= 10;
hours++;
}
cout << "Battery depleted!" << endl;
// Output:
// Hour 0: Battery at 100%
// Hour 1: Battery at 90%
// ...
// Hour 9: Battery at 10%
// Hour 10: Battery at 0%
// Battery depleted!
return 0;
}
Python - Break Statement
Exit a loop prematurely when a certain condition is met.
# Finding the first prime number after a given number
def is_prime(n):
if n < 2:
return False
for i in range(2, int(n**0.5) + 1):
if n % i == 0:
return False
return True
start = 1000
current = start + 1
while True:
if is_prime(current):
print(f"The first prime number after {start} is {current}")
break
current += 1
# Output: The first prime number after 1000 is 1009
C++ - Break Statement
Exit a loop prematurely in C++ when a certain condition is met.
#include <iostream>
#include <cmath>
using namespace std;
bool is_prime(int n) {
if (n < 2) return false;
for (int i = 2; i <= sqrt(n); i++) {
if (n % i == 0) return false;
}
return true;
}
int main() {
int start = 1000;
int current = start + 1;
while (true) {
if (is_prime(current)) {
cout << "The first prime number after " << start << " is " << current << endl;
break;
}
current++;
}
// Output: The first prime number after 1000 is 1009
return 0;
}
Python - Continue Statement
Skip the rest of the current iteration and continue with the next one.
# Printing even numbers and replacing odd numbers with "Odd"
numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
for num in numbers:
if num % 2 != 0:
continue
print(num, end=" ")
# Output: 2 4 6 8 10
C++ - Continue Statement
Skip the rest of the current iteration and continue with the next one in C++.
#include <iostream>
#include <vector>
using namespace std;
int main() {
vector<int> numbers = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
for (int num : numbers) {
if (num % 2 != 0) {
continue;
}
cout << num << " ";
}
// Output: 2 4 6 8 10
return 0;
}
Python - List Comprehension
Create new lists based on existing lists in a concise way.
# Converting temperatures from Celsius to Fahrenheit
celsius = [0, 10, 20, 30, 40]
fahrenheit = [((9/5) * temp + 32) for temp in celsius]
print("Celsius: ", celsius)
print("Fahrenheit:", fahrenheit)
# Output:
# Celsius: [0, 10, 20, 30, 40]
# Fahrenheit: [32.0, 50.0, 68.0, 86.0, 104.0]
C++ - Range-based For Loop
Iterate over elements in a container or array without using indices.
#include <iostream>
#include <vector>
using namespace std;
int main() {
vector<string> fruits = {"apple", "banana", "cherry", "date"};
for (const auto& fruit : fruits) {
cout << "I like " << fruit << "!" << endl;
}
// Output:
// I like apple!
// I like banana!
// I like cherry!
// I like date!
return 0;
}
Wrap-up: Python vs C++ Control Structures and Loops
| Feature | Python | C++ |
|-------------------|------------------------------------------|------------------------------------------|
| Syntax | More readable, less verbose | More verbose, requires semicolons |
| Indentation | Meaningful, defines code blocks | Uses braces {} to define code blocks |
| For loops | for item in iterable: | for (int i = 0; i < n; i++) {} |
| While loops | while condition: | while (condition) {} |
| If statements | if condition: | if (condition) {} |
| List comprehension| [expression for item in iterable] | Not available (use std::transform) |
| Range-based for | for item in iterable: | for (auto& item : container) {} |
| Switch statement | Not available (use if-elif-else) | switch (variable) { case value: ... } |
| Break/Continue | break and continue keywords | break and continue keywords |
| Error handling | try-except blocks | try-catch blocks |