C program to check whether a number is even or odd|5 ways

C program to check whether a number is even or odd|7 ways

In this tutorial, we will discuss the C program to check whether a number is even or odd|7 ways

In this post, we are going to learn how to check whether the given numbers is even or odd using different 7 ways in C language

Code to check whether a number is even or odd

Check whether a number is even or odd – using standard method

Program 1

#include <stdio.h>
#include <stdlib.h>

int main()
{
    int num=78;
    if(num%2==0){
         printf("%d is even\n",num);
    }
    else{
         printf("%d is odd\n",num);
    }
 getch();

    return 0;
}

When the above code is executed, it produces the following result

78 is even

 

In this program,

• integer variables num is declared and initialized
• The given number is tested whether it is odd or even using modular operator
• Then,the program is displayed the output of using printf() function.

 

Check whether a number is even or odd – using user input

Program 2

#include <stdio.h>
#include <stdlib.h>

int main()
{
    int num;//declare the variable
    printf("Enter a number: ");
    scanf("%d",&num);//read the input from the user
    if(num%2==0){
         printf("%d is an even\n",num);
    }
    else{
         printf("%d is an odd\n",num);
    }
 getch();

    return 0;
}

When the above code is executed, it produces the following result

Case 1

Enter a number: 456
456 is an even

Case 2

Enter a number: 125
125 is an odd

 

Approach

 

Check whether a number is even or odd – using divisional operator

Program 3

#include <stdio.h>
#include <stdlib.h>

int main()
{
    int num;
    printf("Enter a integer number: ");
    scanf("%d",&num);//read the input from the user
    //using division operator
    if((num/2)*2==num){
  printf("%d is an Even number",num);
}else{
 printf("%d is an Odd number",num);
}
getch();
    return 0;
}

When the above code is executed, it produces the following result

case 1

Enter a integer number :456
456 is an even number

case 2

Enter a integer number :451
451 is an odd number

 

Approach

 

Check whether a number is even or odd – using switch case

Program 4

#include <stdio.h>
#include <stdlib.h>

int main()
{
    int num;
   /* int num1=450;
  int num2=561;*/
  printf("Enter any number to check odd or even\n");
  scanf("%d",&num);//read the input from the user
switch(num%2){
case 0:
    printf("%d is a even number",num);
  break;
case 1:
    printf("%d is a odd number",num);
}
getch();
    return 0;
}

When the above code is executed, it produces the following result

case 1

Enter any number to check odd or even
9876
9876 is an even number

case 2

Enter any number to check odd or even
987
987 is an odd number

 

Approach

Check whether a number is even or odd – using user defined function

Program 5

#include <stdio.h>
#include <stdlib.h>
int findOddeven(int);//function prototype
int main()
{
    int num;
    printf("Enter a integer number: ");
    scanf("%d",&num);
  //read input from the user
findOddeven(num);//function call
getch();
    return 0;
}

findOddeven(int num){//function definition
if((num%2)==0){
  printf("%d is a Even number",num);
}else{
 printf("%d is a Odd number",num);
}

}

When the above code is executed, it produces the following result

case 1

Enter a integer number :147
147 is an odd number

case 2

Enter a integer number :346
346 is an even number

 

Approach

• Declare a function named as findOddeven(int); with parameter
• integer variables num is declared.
• The program asks input from the user
• Then the user enters the input values for num.
• The program will read the input using scanf() and store the variable num.
• Define the function  findOddeven(); to find whether the number is odd or even
• Call the function to produce output
• finally, the program displays the output using printf() function

 

Check whether a number is even or odd – using pointer

Program 6

#include <stdio.h>
#include <stdlib.h>

int main()
{
    int num,*ptr;//declare the pointer and normal variable
    printf("Enter number to check for odd/even\n");
    scanf("%d",&num);//read input from the user
    ptr=&num;//assign address of num variable to pointer variable

    if(*ptr %2 ==0)//check value for even
        printf("%d is an even",num);
    else
         printf("%d is an odd",num);
getch();

    //printf("Hello world!\n");
    return 0;
}

When the above code is executed, it produces the following result

Case 1

Enter number for check odd/even
456
456 is an even

Case 2

Enter number for check odd/even
457
456 is an odd

 

Approach

 

Check whether a number is even or odd – using recursion

Program 7

#include <stdio.h>
#include <stdlib.h>

int findOddeven(int);
int main()
{
    int num;
   printf("Enter a integer number: ");
    scanf("%d",&num);
  //read input from the user

  if(findOddeven(num)){
  printf("%d is an Even number",num);
}else{
  printf("%d is an Odd number",num);
}

getch();
    return 0;
}

int findOddeven(int num){//function definition
if(num==0){
  return 1;
}else if(num==1){
  return 0;
}
else if(num<0){
  return findOddeven(-num);
}
else{
  return findOddeven(num-2);

}
}

When the above code is executed, it produces the following result

case 1

Enter a integer number: 1234
1234 is an even number

case 2

Enter a integer number: 1237
1237 is an odd number

 

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