Tag: c loop programs

do-while loop in C is just as same as while loop, the only difference is that in do-while the condition is always executed after the loop as shown in the syntax below.

Unlike while loop, where the body of the loop is executed only if the condition stated is true but in the do-while loop, the body of the loop is executed at least once. do-while is an exit-control loop that is it checks the condition after the first execution of the block.

do-while Flowchart:

Syntax of do-while Loop.

do
 {
  statements..
 }while (condition);

---

Example of a do-while loop in C program.

#include <stdio.h>

int main()
{
  int num = 1;

 	//execution of do-while loop
  do {
    printf("Value of num: %d\n", num);
    num++;
  } while (num <= 10);	//condition

  return 0;
}

The output of do-while loop.

Value of num: 1
Value of num: 2
Value of num: 3
Value of num: 4
Value of num: 5
Value of num: 6
Value of num: 7
Value of num: 8
Value of num: 9
Value of num: 10

---

A while loop is a straightforward loop and is also an entry-control loop. It evaluates the condition before executing the block of the loop. If the condition is found to be true, only then the body of the loop is executed. The loop continues until the condition stated is found to be false.

while loop Flowchart:

Syntax of While Loop.

 while(condition)
  {  
    //block of code to be executed  
  } 

---

Example of while loop in C Program

#include <stdio.h>

int main()
{
 	//varibale
  int num = 1;

 	//execution of while loop
  while (num < 10)
  {
    printf("The value of num: %d\n", num);
    num++;
  }

  return 0;
}

The output of while loop in C programming.

The value of num: 1
The value of num: 2
The value of num: 3
The value of num: 4
The value of num: 5
The value of num: 6
The value of num: 7
The value of num: 8
The value of num: 9

---

In C programming, for loop is a more efficient loop structure and is an entry-control loop. The iteration continues until the stated condition becomes false.

It has three computing steps as shown in the syntax below.

• initialization: The first step is the initialization of the variable and is executed only once. And need to end with a semicolon(;).
• condition: Second is condition check, it checks for a boolean expression. If true then enter the block and if false exit the loop. And need to end with a semicolon(;).
• Increment or Decrement: The third one is increment or decrement of the variable for the next iteration. Here, we need to use the semicolon(;).

for loop Flowchart:

Syntax of for loop.

 for(initialization; condition; Increment or Decrement) 
 {
  // Statements
 } 

---

Example of for loop in C Program.

#include <stdio.h>

int main()
{
  int num;

 //execution of for loop
  for (num = 5; num <= 10; num++)
  {
    printf("The values of num: %d\n", num);
  }

  return 0;
}

The output of for loop in C programming.

The values of num: 5
The values of num: 6
The values of num: 7
The values of num: 8
The values of num: 9
The values of num: 10

---

A switch statement allows a variable to be tested for equality against multiple values and each of those values is called a case. It can be used instead of nested if...else.

Switch expression and case value must be of the same type. There must be at least one case or multiple cases with unique case values. In the end, it can have a default case which is optional that is executed if no cases are matched.

Syntax

Syntax of switch statement in C:

switch (expression)
{
    case value1:    
    //code to be executed;    
    break;  //optional  
    case value2:    
    //code to be executed;    
    break;  //optional  
    .
    .
    .
    .    
    case valueN:    
    //code to be executed;    
    break;  //optional 
        
    default:     
    code to be executed if all cases are not matched;    
  }

Switch statement Flowchart:

Example of switch statement in C.

#include <stdio.h>

int main()
{
  //local variable definition
  char grade = 'D';

  switch (grade)
  {
    case 'A':
      printf("Excellent!\n");
      break;
    case 'B':
      printf("Very Good!\n");
      break;
    case 'C':
      printf("Well done\n");
      break;
    case 'D':
      printf("GRADE D\n");
      break;
    case 'F':
      printf("Better try again\n");
      break;
    default:
      printf("Invalid grade\n");
  }

  printf("You Pass with Grade: %c\n", grade);

  return 0;
}

The output of the switch statement in C.

GRADE D
You Pass with Grade: D

---

The use of switch statement inside another switch statement is called nested switch statement.

Syntax

Syntax of nested switch statement in C:

switch(ch1) {

   case 'A': 
      printf("This A is part of outer switch" );
      
      //use of another switch statement
      switch(ch2) {
         case 'A':
            printf("This A is part of inner switch" );
            break;
         case 'B': /* case code */
      }
	  
      break;
   case 'B': /* case code */
}

Example of nested switch statements in C:

#include <stdio.h>

int main()
{
  //local variable
  int a = 10;
  int b = 20;

  switch (a)
  {
    case 10:
      printf("The OUTER Switch.\n", a);

      //INNER Switch
      switch (b)
      {
        case 20:
          printf("The INNER Switch.\n", a);
      }
  }

  return 0;
}

The output of nested switch statements in C.

The OUTER Switch.
The INNER Switch.

---

An if statement consists of a Boolean expression followed by one or more statements.
If the boolean expression is true, the block of code inside the if statement will be executed else not.

Syntax

Syntax of if statement in C:

 if (boolean expression)
  {
   /* if expression is true */
   statements... ; /* Execute statements */
  }

if statement Flowchart:

Example of if statement in C Program:

#include <stdio.h>

void main()
{
  int num1, num2;

  num1 = 90;
  num2 = 50;

  if (num1 > num2)
  {
    printf("num1 is greater than num2");
  }
}

The output of if statement in C.

num1 is greater than num2

---

If the Boolean expression is true then the code inside the if statement block is executed or if it is false then the code inside else statement will be executed. Hence if..else statement.

Syntax

Syntax of if...else statement in C Language:

 if (condition) 
 {
  //code executed if condition true 
 }
 else
 {
  //code executed if condition false 
 }

If…else Flowchart:

Example of if…else statement in C.

#include <stdio.h>

void main()
{
  int num1, num2;

  num1 = 56;
  num2 = 89;

  if (num1 > num2)
  {
    printf("num1 is greater than num2y");
  }
  else
  {
    printf("num2 is greater than num1");
  }
}

The output of if…else statement in C.

num2 is greater than num1

---

This statement allows the user to use if block inside the other if block. And the inner if statement is executed only if the outer if statement’s condition is true.

Syntax

Syntax of nested if statement in C:

if(condition1)
 {    
    //block of code to be executed    
    if(condition2)
    {  
      //block of code to be executed    
    }    
 } 

nested if Flowchart:

Example of nested if statement in C:

#include <stdio.h>

int main()
{
  // local variable
  int num1 = 60;
  int num2 = 90;

  // first if statement
  if (num1 > 50)
  {
    // if inside if statement
    if (num2 > 80)
    {
      printf("Actual value of num1 is : %d\n", num1);
      printf("Actual value of num2 is : %d\n", num2);
    }
  }

  return 0;
}

The output of nested if statement in C.

Actual value of num1 is : 60
Actual value of num2 is : 90

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