SWITCH STATEMENT AND LOOPS IN C++

SWITCH STATEMENT:

6 min readDec 22, 2023

In C++, theswitch statement provides a way to make decisions based on the value of a variable or expression. It's particularly useful when you have a variable with discrete, integral values (like integers or characters) and want to execute different code blocks based on its value.

Here’s the basic structure of a switch statement:

Explanation:

switch (expression)begins theswitch statement where expression is evaluated. This expression should result in an integral type (like int, char, enum, etc.).
case value1: and case value2:: These are the different cases that the expression might match. If the expression matches value1, the code block following case value1: will be executed. If it matchesvalue2, the code block followingcase value2: will be executed, and so on.
break;This statement is used to exit the switch block. After executing the code for a matching casecase, thebreak statement ensures that the program doesn't continue executing the code for subsequent cases. If break is omitted, execution will continue to the nextcase, potentially causing unintended behavior.
default:(optional): This is used when none of the cases match the value of theexpression. It's similar to an else in an if-else statement. If nodefault is specified and no cases match, the switch statement simply completes without any specific action.

Example:

In this example, the program will output “Wednesday” because the value of day is 3, and it matches the case 3: label in the switch statement. Thebreak; statement ensures that once a matching case is found and executed, the switch statement exits without checking further cases. If day were 6, thedefault case would execute, printing "Weekend.".

LOOPS:

For Loop:

The for loop in C++ is a control flow statement used for iterating a specific number of times. It's commonly used when the number of iterations is known beforehand.

Here’s the structure of a for loop:

Explanation:

initializationtypically initializes a counter variable used in the loop. It runs only once at the beginning of the loop.
conditionspecifies the condition for executing the loop. It's evaluated before each iteration. If the condition is true, the loop continues; otherwise, it terminates.
updatemodifies the counter variable or any other variables used in the loop after each iteration.
The code block within curly braces{} is the body of the loop, containing the code to be executed repeatedly as long as the condition remains true.

Example:

Explanation of the example:

int i = 0;initializes the loop counter i to 0.
i < 5;is the condition. The loop will continue as long as i is less than 5.
++iincrementsi by 1 in each iteration (i++ or i += 1 would have the same effect). This is the update step.

In this example, the loop starts with i = 0 and continues until i becomes equal to 5. The loop body prints the value ofi each time it runs, resulting in output from 0 to 4.

While Loop:

while loop in C++ is a control flow statement used for the repetitive execution of a block of code based on a condition. It continues to execute as long as the condition remains true.

Here’s the structure of a while loop:

Explanation:

conditionA boolean expression or a condition that controls the loop. If the condition is true, the loop continues to execute; otherwise, it terminates.
The code block within curly braces{} is the body of the loop, containing the code to be executed repeatedly as long as the condition remains true.

Example:

Explanation of the example:

int j = 0;initializes a counter variablej to 0 before the loop starts.
while (j < 5)specifies the condition for the loop to continue. As long as j is less than 5, the loop will execute.
++j;incrementsj by 1 in each iteration. This step is crucial to avoid an infinite loop; without it, the loop will continue indefinitely.

In this example, the loop starts with j = 0 and continues until j becomes equal to 5. Inside the loop, the value of j is printed, resulting in output from 0 to4.

Thewhile loop is useful when the number of iterations is not known beforehand and the loop needs to execute based on a condition. Ensure that the condition eventually becomes false to avoid infinite loops.

Do While Loop:

do-while loop in C++ is a control flow statement that executes a block of code at least once and then repeatedly executes the block as long as a specified condition is true.

Here’s the structure of a do-while loop:

Explanation:

The code block within curly braces{} is the body of the loop, containing the code to be executed.
conditionA boolean expression or a condition that controls the loop. The loop continues to execute as long as this condition remains true.
Thedo keyword initiates the loop and guarantees the code block is executed at least once before checking the condition.

Example:

Explanation of the example:

int k = 0;initializes a counter variablek to 0 before the loop starts.
do { ... }defines the block of code to be executed. In this case, it simply prints the value ofk.
while (k < 5);specifies the condition for the loop to continue. As long as k is less than 5, the loop will execute.
++k;incrementsk by 1 in each iteration.

In this example, the loop starts withk = 0, and the value of k is printed. Then, it incrementsk by 1 and repeats this process until k becomes equal to 5. Therefore, the output will be from 0 to 4.

The do-while loop is particularly useful when you need to execute a block of code at least once, regardless of the condition. It ensures that the code within thedo block executes before checking the condition for the first time.

Ranged Based For Loop:

The range-basedfor loop in C++11 later allows you to iterate over elements in a range, such as arrays, containers, or sequences, without the need for explicit indexing.

Here’s the structure of a range-based for loop:

Explanation:

element_typeThe type of each element in the range. It's often automatically deduced based on the range.
elementThe variable that will represent each element in the range.
rangeThe collection or sequence over which the loop will iterate.

Example:

Explanation of the example:

vector<int> numbers = {1, 2, 3, 4, 5};creates a vector numbers containing integers.
for (int number : numbers)initiates a loop that iterates over each element in the numbers vector.
int numberrepresents each element in the vector andcout << number << " "; prints each number followed by a space.
The loop iterates through thenumbers vector, printing each element, resulting in an output1 2 3 4 5.

The range-basedfor loop simplifies iteration over containers or sequences by handling the iteration logic internally, making the code cleaner and less error-prone compared to traditional indexed loops.

SWITCH STATEMENT AND LOOPS IN C++