Control Statements

In C, control statements are fundamental constructs that use loops and conditions to determine how a program should execute. They give programmers the ability to deliberately, frequently, or in reaction to certain scenarios run individual code blocks.

C supports two main types of control statements:

Conditional Statements

Conditional statements in C are used to make decisions and execute specific blocks of code depending on whether a condition evaluates to true or false. Some of the conditional statement constructs supported in C are if,else, else if, and switch statement.

if Statement

The if statement is used to execute a code block only if a specified condition evaluates to true:

if (condition) {
  // Code to execute if condition is true
}

Here’s an example code snippet demonstrating the use of if statement in C:

#include <stdio.h>

int main() {
  int number = 10;

  // Check if the number is greater than 5
  if (number > 5) {
    printf("Greater than 5\n");
  }

  return 0;
}

The output for the code would be:

Greater than 5

if-else Statement

The if-else statement is used for executing a code block only if a specified condition comes true and another if it comes false:

if (condition) {
  // Code to execute if condition is true
} else {
  // Code to execute if condition is false
}

Here’s an example code snippet demonstrating the use of if-else statement in C:

#include <stdio.h>
int main() {
  int number = 3;

  // Check if the number is greater than 5
  if (number > 5) {
    printf("Greater than 5\n");
  } else {
    printf("5 or less\n");
  }

  return 0;
}

The output for the code would be:

5 or less

switch Statement

The switch statement executes one of several blocks of code based on the value of a variable:

switch (variable) {
  case value1:
    // Code for case value1
    break;
  case value2:
    // Code for case value2
    break;
  default:
    // Code if no cases match
}

Here’s an example code snippet demonstrating the use of switch statement in C:

#include <stdio.h>
int main() {
  int day = 6;

// Determine the day of the week
  switch (day) {
    case 1:
      printf("Monday\n");
      break;
    case 2:
      printf("Tuesday\n");
      break;
    case 3:
      printf("Wednesday\n");
      break;
    case 4:
      printf("Thursday\n");
      break;
    case 5:
      printf("Friday\n");
      break;
    case 6:
      printf("Saturday\n");
      break;
    case 7:
      printf("Sunday\n");
      break;
    default:
      printf("Invalid day\n");
  }

  return 0;
}

The output for the code would be:

Saturday

Looping Statements

Looping statements in C are used to repeatedly execute a code block until a specific condition comes false. This helps developers avoid the repetition of tasks and minimizes the duplication of code in their programs.

for loop

In C, the for loop allows users to run a block of code multiple times, making it ideal for situations where they know exactly how many iterations are needed:

for (initialization; condition; update) {
  // Code to execute in each iteration
}

Here’s an example code snippet demonstrating the use of for statement in C:

#include <stdio.h>

int main() {
  // Using a for loop to print numbers 1 to 5
  for (int i = 1; i <= 5; i++) {
    printf("Iteration: %d\n", i);
  }
  return 0;
}

The output for the code would be:

Iteration: 1
Iteration: 2
Iteration: 3
Iteration: 4
Iteration: 5

while loop

The while loop in C executes a code block repeatedly until a specific condition comes false. It’s mostly used when the number of iterations needed are not known:

while (condition) {
  // Code to execute while condition is true
}

Here’s an example code snippet demonstrating the use of while loop in C:

#include <stdio.h>
int main() {
  int i = 1;

  // While loop will execute as long as i is less than or equal to 5
  while (i <= 5) {
    printf("%d\n", i);  // Print the value of i
    i++;  // Increment i by 1
  }
  return 0;
}

The output for the code would be:

1
2
3
4
5

do-while loop

A do-while loop in C resembles a while loop with a difference. The condition is tested after the loop body is executed and not before, which is how it’s executed at least once regardless of the condition. In a do-while loop, execution continues as long as the given condition is met:

do {
  // Block of code to be executed
} while (condition);

Here’s an example code snippet demonstrating the use of do-while loop in C:

#include <stdio.h>
int main() {
  int count = 1;

  // do-while loop to print numbers 1 to 5
  do {
    printf("Count: %d\n", count);
    count++;
  } while (count <= 5);

  return 0;
}

The output for the code would be:

Count: 1
Count: 2
Count: 3
Count: 4
Count: 5