07 - Conditionals

if-else statements

We already know that C++ supports the usual logic conditions from mathematics

• Less than a < b
• Less than or Equal to a <= b
• Greater than a > b
• Greater than or Equal to a >= b
• Equal to a == b
• Not Equal to a != b

We can use these conditionals to perform different actions for different (values) decisions.

C++ has the following conditional statements:

• Use if to specify a block of code to be executed, if a specified condition is true.

int x = 5;
int y = 7;

if (x > y) {
    cout << "X is greater than Y";
}

• Use else to specify a block of code to be executed if the same condition is false.

int x = 5;
int y = 7;

if (x > y) {
    cout << "X is greater than Y";
} else {
    cout << "Y is greater than X";
}

• Use else if to specify a new condition to test, if the first condition is false.

int x = 5;
int y = 7;

if (x > y) {
    cout << "X is greater than Y";
} else if (x == y){
    cout << "X and Y are identical";
} else {
    cout << "Y is greater than X";
}

Ternary Operator

Ternary Operator is the replacement of simple if-else statement.

int x = 5;
int y = 7;

string result = (x > y) ? "X is greater than Y" : "Y is greater than X";
cout << result;

Note

Syntax of Ternary operator

(condition) ? true : false

Switch Statement

Use the switch statement to select one of many code blocks to be executed.

• The switch expression is avaluated once.
• The value of the expression is compared with the value of each case
• If there is a match, the associated block of code is executed.
• The break and default keywords are optional.

int day = 4;

switch (day) {
    case 1 :
        cout << "Monday";
        break;
    case 2 :
        cout << "Tuesday";
        break;
    case 3 :
        cout << "Wednesday";
        break;
    case 4 :
        cout << "Thrusday";
        break;
    case 5 :
        cout << "Friday";
        break;
    case 6 :
        cout << "Saturday";
        break;
    case 7 :
        cout << "Sunday";
        break;
    default :
        cout << "Not a valid day";
        break;
}

Break Keyword

When C++ reaches a break keyword, it breaks out of the switch block.

This will stop the execution of more code and case testing inside the block.

When a match is found, and the job is done, it's time for a break.
There is no need for more testing.

Note

A break can save a lot of execution time because it ignores the execution of all the rest of the code in the switch block.

Default Keyword

The default keyword specifies some code to run if there is no case match.

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Happy Coding 💖