Constructs:

There are two types of constructs in C programming language.

1. Conditional Constructs.

2. Loop Constructs.

Conditional Constructs are two types.    A) If … else statements.    B) Switch case.

Loop Constructs are three types.     A) For loop.  B) While loop.  C) Do … while loop.

If else :

#include<stdio.h>

void main()

{

int x;

printf("Enter a number :\n");

scanf("%d",&x);

if(x%2==0)

{

printf("It's a EVEN number \n");

}

else

{

printf("It's a ODD number \n");

}

}

Switch case :

#include<stdio.h>

void main()

{

printf("1. Sum\n");

printf("2. Substract\n");

printf("3. Multi\n");

printf("4. Div\n");

printf("Enter your choice :\n");

int x;

scanf("%d",&x);

switch(x)

{

int a,b,c;

case 1:

printf(":::  Sum  :::\n");

printf("Enter two numbers :\n");

scanf("%d%d",&a,&b);

c=a+b;

printf("Sum of two numbers is %d\n",c);

break;

case 2:

printf(":::  Substract  :::\n");

printf("Enter two numbers :\n");

scanf("%d%d",&a,&b);

c=a-b;

printf("Substract of two numbers is %d\n",c);

break;

case 3:

printf(":::  Multi  :::\n");

printf("Enter two numbers :\n");

scanf("%d%d",&a,&b);

c=a*b;

printf("Multi of two numbers is %d\n",c);

break;

case 4:

printf(":::  Div  :::\n");

printf("Enter two numbers :\n");

scanf("%d%d",&a,&b);

c=a/b;

printf("Division of two numbers is %d\n",c);

break;

default:

printf(" Invalid Choice. \n");

}

}

LOOP :-

For loop :

#include<stdio.h>

void main()

{

int x,sum,cnt;

printf(":::  Sum of 5 numbers  :::\n\n");

printf("Enter 5 numbers :\n");

for(cnt=sum=0;cnt<5;cnt++)

{

scanf("%d",&x);

sum=sum+x;

}

printf("The result is :%d\n",sum);

}

While loop : 

#include<stdio.h>

void main()

{

int x,sum,cnt;

cnt=sum=0;

printf(":::  Sum of 5 numbers  :::\n\n");

printf("Enter 5 numbers :\n");

while(cnt<5)

{

scanf("%d",&x);

sum=sum+x;

cnt++;

}

printf("The result is :%d\n",sum);

}

Do ... while loop :

#include<stdio.h>

void main()

{

int x,sum,cnt;

cnt=sum=0;

printf(":::  Sum of 5 numbers  :::\n\n");

printf("Enter 5 numbers :\n");

do

{

scanf("%d",&x);

sum=sum+x;

cnt++;

}while(cnt<5);

printf("The result is :%d\n",sum);

}

The preceding snippet is output of the above loop programs...