Conditional statements in Python and C++ are very similar.

Simple if

In Python, we write a simple if statement in the following way:

if condition:
    statement1
    statement2
    ...

In C++ this same pattern is simply written as:

if (condition) {
    statement1;
    statement2;
    ...
}

Once again you can see that in C++ the curly braces define a block rather than indentation. In C++ the parenthesis around the condition are required because if is technically a function that evaluates to true or false.

if else

The if-else statement in Python looks like this:

if condition:
    statement1
    statement2
    ...
else:
    statement1
    statement2
    ...

In C++ this is written as:

if (condition) {
    statement1;
    statement2;
    ...
} 
else {
    statement1;
    statement2;
    ...
}

elif

C++ does not have an elif pattern like Python. In C++ you can get the functionality of an elif statement by nesting if and else. Here is a simple example in both Python and C++.

code python:

    grade = 85
    if grade < 60:
        print('F')
    elif grade < 70:
        print('D')
    elif grade < 80:
        print('C')
    elif grade < 90:
        print('B')
    else:
        print('A')

In C++ we have a couple of ways to write this code cpp:

#include <iostream>
using namespace std;

int main() {
    int grade = 85;

    if (grade < 60) {
        cout << "F" << endl;
    } 
    else if (grade < 70) {
        cout << "D" << endl;
    } 
    else if (grade < 80) {
        cout << "C" << endl;
    } 
    else if (grade < 90) {
        cout << "B" << endl;
    } 
    else {
        cout << "A" << endl;
    }

    return 0;
}

We can get even closer to the elif statement by taking advantage of the C++ rule that a single statement does not need to be enclosed in curly braces. Since the if is the only statement used in each else we can get away with the following.

switch

C++ also supports a switch statement that acts something like the elif statement of Python under certain conditions because the statement takes cases and checks the validity of the case against the code. To write the grade program using a switch statement we would use the following.

code python:

grade = 85
tempgrade = grade // 10 

match tempgrade:
    case 10 | 9:  # 90-100
        print("A")
    case 8:  # 80-89
        print("B")
    case 7:  # 70-79
        print("C")
    case 6:  # 60-69
        print("D")
    case _:  # <60
        print("F")

code cpp:

#include <iostream>
using namespace std;

int main() {
    int grade = 85;
    int tempgrade = grade / 10;

    switch(tempgrade) {
        case 10:  // 100
        case 9:   // 90-99
            cout << "A" << endl;
            break;
        case 8:   // 80-89
            cout << "B" << endl;
            break;
        case 7:   // 70-79
            cout << "C" << endl;
            break;
        case 6:   // 60-69
            cout << "D" << endl;
            break;
        default:  // <60
            cout << "F" << endl;
    }

    return 0;
}

The switch statement is not used very often, and I recommend you do not use it! First, it is not as powerful as the else if model because the switch variable can only be compared for equality with an integer or enumerated constant. Second it is very easy to forget to put in the break statement. If the break statement is left out then then the next alternative will be automatically executed. For example if the grade was 95 and the break was omitted from the case 9: alternative then the program would print out both (A and B.)

Boolean Operators

{sub:boolean_operators}

The conditionals used in the if statement can be boolean variables, simple comparisons, and compound boolean expressions.

C++ also supports the boolean expression. condition ? trueValue : falseValue This expression can be used to test a condition as part of an assignment statement. For example a = a % 2 == 0 ? a*a : 3*x -1 In the previous assignment statement the expression a%2 ==0 is first checked. If it is true then a is assigned the value a * a if it is false then a is assigned the value of 3*x-1. Of course all of this could have been accomplished using a regular if else statement, but sometimes the convenience of a single statement is too much to resist.