What are C++ control flow statements?

C++ Control Flow Statements

In C++, control flow statements are used to control the order of execution of code within a program. These statements allow the program to make decisions, repeat actions, and alter the normal sequential flow of execution. The main control flow statements in C++ are:

1. Conditional Statements:

   • if-else statement: Allows the program to make decisions based on a condition.
   • switch statement: Provides a multi-way decision-making mechanism.

2. Iterative Statements:

   • for loop: Executes a block of code a specific number of times.
   • while loop: Executes a block of code as long as a condition is true.
   • do-while loop: Executes a block of code at least once, and then continues to execute the block as long as a condition is true.

3. Jump Statements:

   • break statement: Terminates the current loop or switch statement.
   • continue statement: Skips the current iteration of a loop and moves to the next iteration.
   • goto statement: Transfers control to a labeled statement within the same function.
   • return statement: Terminates the current function and returns control to the calling function.

Here's a Mermaid diagram that illustrates the main C++ control flow statements:

Let's explore these control flow statements in more detail:

Conditional Statements

if-else statement:
The if-else statement allows the program to make decisions based on a condition. If the condition is true, the code block inside the if statement is executed; otherwise, the code block inside the else statement is executed.

Example:

int age = 18;
if (age >= 18) {
    std::cout << "You are an adult." << std::endl;
} else {
    std::cout << "You are a minor." << std::endl;
}

switch statement:
The switch statement provides a multi-way decision-making mechanism. It evaluates an expression and executes the corresponding case statement. If none of the case statements match, the optional default case is executed.

Example:

int day = 3;
switch (day) {
    case 1:
        std::cout << "Monday" << std::endl;
        break;
    case 2:
        std::cout << "Tuesday" << std::endl;
        break;
    case 3:
        std::cout << "Wednesday" << std::endl;
        break;
    default:
        std::cout << "Invalid day" << std::endl;
        break;
}

Iterative Statements

for loop:
The for loop is used to execute a block of code a specific number of times. It consists of three parts: the initialization, the condition, and the increment/decrement.

Example:

for (int i = 0; i < 5; i++) {
    std::cout << "Iteration " << i << std::endl;
}

while loop:
The while loop executes a block of code as long as a condition is true. The condition is evaluated before each iteration of the loop.

Example:

int count = 0;
while (count < 3) {
    std::cout << "Count: " << count << std::endl;
    count++;
}

do-while loop:
The do-while loop is similar to the while loop, but the condition is evaluated after each iteration of the loop. This ensures that the block of code is executed at least once.

Example:

int i = 0;
do {
    std::cout << "Iteration " << i << std::endl;
    i++;
} while (i < 3);

Jump Statements

break statement:
The break statement is used to terminate the current loop or switch statement.

Example:

for (int i = 0; i < 10; i++) {
    if (i == 5) {
        break;
    }
    std::cout << "Iteration " << i << std::endl;
}

continue statement:
The continue statement skips the current iteration of a loop and moves to the next iteration.

Example:

for (int i = 0; i < 10; i++) {
    if (i % 2 == 0) {
        continue;
    }
    std::cout << "Odd number: " << i << std::endl;
}

goto statement:
The goto statement transfers control to a labeled statement within the same function. However, the use of goto statements is generally discouraged, as they can make the code difficult to read and maintain.

Example:

int x = 0;
start:
    std::cout << "x = " << x << std::endl;
    x++;
    if (x < 5) {
        goto start;
    }

return statement:
The return statement terminates the current function and returns control to the calling function.

Example:

int add(int a, int b) {
    int sum = a + b;
    return sum;
}

int main() {
    int result = add(3, 4);
    std::cout << "The result is: " << result << std::endl;
    return 0;
}

In conclusion, C++ control flow statements provide the necessary tools to create complex and dynamic programs. By understanding and effectively using these statements, you can write code that can make decisions, repeat actions, and control the overall flow of execution. Remember, the key to mastering control flow is to practice and experiment with different scenarios to gain a deeper understanding of their usage and application.