Control Structures C++

 In C++, control structures allow you to control the flow of execution in your programs. These structures dictate how statements are executed based on conditions or repetitions. The main control structures are:

1. Sequential Control

• This is the default mode where the statements are executed one after the other in the order they are written. There is no decision-making or repetition involved.

Text Data:

• Each statement in a program is executed in sequence unless otherwise altered by control structures.
• For example:
  • int a = 5; – This statement is executed.
  • int b = 10; – This is executed immediately after the previous statement.

2. Selection Control Structures

• These structures allow the program to make decisions and execute certain sections of code based on conditions.

Types:

a) if statement:

• Executes a block of code if a specified condition is true.

  Text Data:

  • if (condition) – If the condition evaluates to true, the code block following the if statement is executed.
  • else – If the condition is false, the code block following the else is executed.

  Example:

  • if (age >= 18) – Checks if age is 18 or more.
  • else – Executes if age is less than 18.

b) if-else-if ladder:

• Multiple conditions can be tested in sequence. If one condition is true, the associated block is executed, and the remaining conditions are ignored.

  Text Data:

  • if (condition1) – Checks first condition.
  • else if (condition2) – If condition1 is false, checks condition2.
  • else – Executes if none of the conditions are true.

c) switch statement:

• Provides a way to test multiple values for a single variable and execute different blocks of code depending on the value.

  Text Data:

  • switch(expression) – Tests the value of expression.
  • case value1: – If expression equals value1, execute this block.
  • case value2: – If expression equals value2, execute this block.
  • default: – If none of the cases match, execute this block.

  Example:

  • switch(day) – Tests the value of day.
  • case 1: – Executes if day equals 1 (e.g., Monday).
  • default: – Executes if day is not matched to any case.

3. Repetition (Loop) Control Structures

• Loops are used when you need to repeat a block of code multiple times.

Types:

a) for loop:

• Used when you know in advance how many times the loop should run.

  Text Data:

  • for (initialization; condition; increment/decrement) – The loop continues as long as the condition is true.
  • initialization – Initializes a variable before the loop starts.
  • condition – Evaluates before each iteration; if false, the loop ends.
  • increment/decrement – Updates the variable after each iteration.

  Example:

  • for (int i = 0; i < 10; i++) – Loops 10 times, from i = 0 to i < 10.

b) while loop:

• Repeats a block of code while a specified condition is true. The condition is checked before each iteration.

  Text Data:

  • while (condition) – As long as the condition is true, the loop runs.

  Example:

  • while (count < 5) – Loops as long as count is less than 5.

c) do-while loop:

• Similar to the while loop, but the condition is checked after the code block has been executed, meaning the loop will run at least once.

  Text Data:

  • do { ... } while (condition); – Executes the code once before checking the condition.

  Example:

  • do { sum += x; } while (x > 0); – Adds x to sum at least once and continues while x is greater than 0.

4. Jump Control Structures

• These are used to interrupt the normal flow of control in loops or switch cases.

Types:

a) break statement:

• Used to exit from a loop or switch statement prematurely.

  Text Data:

  • break; – Causes the loop or switch to terminate immediately.

  Example:

  • if (x == 5) break; – Exits the loop if x equals 5.

b) continue statement:

• Causes the loop to skip the current iteration and move to the next one.

  Text Data:

  • continue; – Skips the remaining code and starts the next iteration of the loop.

  Example:

  • if (x % 2 == 0) continue; – Skips the iteration if x is even.

c) return statement:

• Exits a function and optionally returns a value to the caller.

  Text Data:

  • return value; – Exits the function and returns the value.

  Example:

  • return 0; – Returns 0 to indicate successful program execution.

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In summary, control structures in C++ manage the flow of a program by allowing decision-making (selection), repeating actions (loops), and handling early exits (jump control). Understanding and using these control structures effectively is critical for developing complex and efficient programs.