Decision Control Structures – Theory and Programs [Learn to code]

What are Decisions and how computer processes it? Syntax for Decision Control Structures and programs on Decision Control Structures.

  • 014. Write a program to accept two number and print largest among them in C language
     
    #include<stdio.h>
     
    #include<conio.h>
     
    main()
     
    {
     
    int a,b;
     
    clrscr();
     
    printf("Enter numbers : ");
     
    scanf("%d%d",&a,&b);
     
    if(a>b)
     
    printf("Largest value is....%d",a);
     
    else
     
    printf("Largest value is....%d",b);
     
    getch();
     
    }
  • 015. Write a program to accept a number and print if the number is Positive/Negative in C language
    #include<stdio.h>
    #include<conio.h>
     
    main()
    {
     int n;
     clrscr();
     printf("Enter number..");
     scanf("%d",&n);
     if(n>0)
    	printf("Given number is positive");
     else if(n<0)
    	printf("Given number is negative");
     else
    	printf("Number is Zero");
     getch();
    }
  • 016. Write a program to accept a number and check if it is >10, <10 or =10 in C language
    #include<stdio.h>
    #include<conio.h>
    main()
    {
      int n;
      clrscr();
      printf("enter number...");
      scanf("%d",&n);
      if(n>10)
    	printf("Number is greater than 10");
      else if(n<10)
    	printf("Number is lesser than 10");
      else
    	printf("Number is 10");
      getch();
    }
  • 017. Write a program to accept a number from user and print if it is even or odd in C language
    #include<stdio.h>
    #include<conio.h>
    main()
    {
     int n;
     clrscr();
     printf("Enter number...");
     scanf("%d",&n);
     if(n%2==0)
    	printf("Number is even...");
     else
    	printf("Number is odd....");
     getch();
    }
  • 018. Write a program to accept a number from user and print if it is divisible by 5 in C language
    #include<stdio.h>
    #include<conio.h>
    main()
    {
     int n;
     clrscr();
     printf("Enter number...");
     scanf("%d",&n);
     if(n%5==0)
    	printf("Number is divisible by 5.");
     else
    	printf("Number is not divisible by 5.");
     getch();
    }
  • 019. Write a program to accept a number from user and print if it is multiple of 7 in C language
    #include<stdio.h>
    #include<conio.h>
    main()
    {
     int n;
     clrscr();
     printf("Enter number...");
     scanf("%d",&n);
     if(n%7==0)
    	printf("Number is multiple of 7");
     else
    	printf("Number is not multiple of 7");
     getch();
    }
  • 020. Write a program to accept two numbers from user and compare them in C language
    #include<stdio.h>
    #include<conio.h>
    main()
    {
     int a,b;
     clrscr();
     printf("Enter numbers...");
     scanf("%d%d",&a,&b);
     if(a>b)
    	printf("a is greater than b");
     else if(b>a)
    	printf("b is greater than a");
     else
    	printf("both are equal");
     getch();
    }
  • 021. Write a program to accept three numbers from user and print them in ascending and decending order in C language
    #include<stdio.h>
    #include<conio.h> 
    main()
    {
     int a,b,c;
     clrscr();
     printf("Enter numbers...");
     scanf("%d%d%d",&a,&b,&c);
     if((a>=b)&&(a>=c))
     {
        if(b>=c)
        {
         printf("n Descending order : %d %d %d",a,b,c);
         printf("n Ascending order : %d %d %d",c,b,a);
        }
        else
        {
         printf("n Descending order : %d %d %d",a,c,b);
         printf("n Ascending order : %d %d %d",b,c,a);
        }
     }
     else if((b>=a)&&(b>=c))
     {
        if(a>=c)
        {
         printf("n Descending order : %d %d %d",b,a,c);
         printf("n Ascending order : %d %d %d",c,a,b);
        }
        else
        {
         printf("n Descending order : %d %d %d",b,c,a);
         printf("n Ascending order : %d %d %d",a,c,b);
        }
     }
     else if((c>=a)&&(c>=b))
     {
      if(a>=b)
      {
         printf(" Descending order : %d %d %d",c,a,b);
         printf(" Ascending order : %d %d %d",b,a,c);
      }
      else
      {
         printf(" Descending order : %d %d %d",c,b,a);
         printf(" Ascending order : %d %d %d",a,b,c);
      }
    }
     getch();
    }
  • 022. Write a program to calculate roots of a quadratic equations in C language

    x=b^2-4ac
    if x=0 -> only one root ,
    if x>0 -> roots are distinct (–b+x)/2a & (–b-x)/2a
    if x<0 -> roots are imaginary

    #include<stdio.h>
    #include<conio.h>
    main()
    {
     float x,r1,r2,a,b,c;
     clrscr();
     printf("Enter a,b,c...");
     scanf("%f%f%f",&a,&b,&c);
     x=b*b-4*a*c;
     r1=(-b+x)/2*a;
     r2=(-b-x)/2*a;
     if(x>0)
    		printf("nRoots are unequal...n");
     else if(x<0)
    		printf("nRoots are imaginary...n");
     else
    		printf("nRoots are same....n");
     printf("R1 = %f",r1);
     printf("R2 = %f",r2);
     getch();
    }
  • 023. Write a program to accept roll number ,and marks for three subjects, print total marks and average, also print grade by considering following conditions

    Avg>=60 Grade A
    Avg<60,Avg >=50 Grade B
    Avg<50,Avg >=40 Grade C

    Grade F.

    #include<stdio.h>
    #include<conio.h>
    main()
    {
     int RollNumber,m1,m2,m3,total;
     float avg;
     clrscr();
     printf("Enter Roll Number : ");
     scanf("%d",&RollNumber);
     printf("Enter marks for three subjects : ");
     scanf("%d%d%d",&m1,&m2,&m3);
     total=m1+m2+m3;
     avg=total/3.0;
     printf("nTotal is....... %d",total);
     printf("nAverage is..... %5.2f %",avg);
     if(avg>=60)
    	printf("nGrade : A");
    else if((avg>=50)&&(avg<60))
    	printf("nGrade : B");
     else if((avg>=40)&&(avg<50))
    	printf("nGrade : C");
     else
    	printf("nGrade : F");
     getch();
    }
  • 024. Write a Program to accept user’s marital status, gender and age to check if he/she is eligible for marriage or not.
    #include<stdio.h>
    #include<conio.h>
    main()
    {
       int age;
       char MaritalStatus,Gender;
       clrscr();
     printf("Enter MaritalStatus, Gender, Age : (e.g. m,f,25) : ");
       scanf("%c,%c,%d",&MaritalStatus,&Gender,&age);
       if(MaritalStatus=='m')
       {
    		printf("You can not marry!");
       }
       else if(MaritalStatus=='u')
       {
    		if(Gender=='m')
    		{
    			if(age>=21)
    			    printf("You can marry!");
    			else
    			    printf("You can not marry!");
    		}
    		else if(Gender=='f')
    		{
    			if(age>=18)
    			    printf("You can marry!");
    			else
    			    printf("You can not marry!");
    		}
    		else
    		      printf("Invalid input Gender");
       }
       else
    printf("Invalid input Marital Status ");
       getch();
    }

024. Write a Program to accept user’s marital status, gender and age to check if he/she is eligible for marriage or not.

#include<stdio.h>
#include<conio.h>
main()
{
   int age;
   char MaritalStatus,Gender;
   clrscr();
 printf("Enter MaritalStatus, Gender, Age : (e.g. m,f,25) : ");
   scanf("%c,%c,%d",&MaritalStatus,&Gender,&age);
   if(MaritalStatus=='m')
   {
		printf("You can not marry!");
   }
   else if(MaritalStatus=='u')
   {
		if(Gender=='m')
		{
			if(age>=21)
			    printf("You can marry!");
			else
			    printf("You can not marry!");
		}
		else if(Gender=='f')
		{
			if(age>=18)
			    printf("You can marry!");
			else
			    printf("You can not marry!");
		}
		else
		      printf("Invalid input Gender");
   }
   else
printf("Invalid input Marital Status ");
   getch();
}

023. Write a program to accept roll number ,and marks for three subjects, print total marks and average, also print grade by considering following conditions

Avg>=60 Grade A
Avg<60,Avg >=50 Grade B
Avg<50,Avg >=40 Grade C

Grade F.

#include<stdio.h>
#include<conio.h>
main()
{
 int RollNumber,m1,m2,m3,total;
 float avg;
 clrscr();
 printf("Enter Roll Number : ");
 scanf("%d",&RollNumber);
 printf("Enter marks for three subjects : ");
 scanf("%d%d%d",&m1,&m2,&m3);
 total=m1+m2+m3;
 avg=total/3.0;
 printf("\nTotal is....... %d",total);
 printf("\nAverage is..... %5.2f %",avg);
 if(avg>=60)
	printf("\nGrade : A");
else if((avg>=50)&&(avg<60))
	printf("\nGrade : B");
 else if((avg>=40)&&(avg<50))
	printf("\nGrade : C");
 else
	printf("\nGrade : F");
 getch();
}

022. Write a program to calculate roots of a quadratic equations in C language

x=b^2-4ac
if x=0 -> only one root ,
if x>0 -> roots are distinct (–b+x)/2a & (–b-x)/2a
if x<0 -> roots are imaginary

#include<stdio.h>
#include<conio.h>
main()
{
 float x,r1,r2,a,b,c;
 clrscr();
 printf("Enter a,b,c...");
 scanf("%f%f%f",&a,&b,&c);
 x=b*b-4*a*c;
 r1=(-b+x)/2*a;
 r2=(-b-x)/2*a;
 if(x>0)
		printf("\nRoots are unequal...\n");
 else if(x<0)
		printf("\nRoots are imaginary...\n");
 else
		printf("\nRoots are same....\n");
 printf("R1 = %f",r1);
 printf("R2 = %f",r2);
 getch();
}

021. Write a program to accept three numbers from user and print them in ascending and decending order in C language

#include<stdio.h>
#include<conio.h> 
main()
{
 int a,b,c;
 clrscr();
 printf("Enter numbers...");
 scanf("%d%d%d",&a,&b,&c);
 if((a>=b)&&(a>=c))
 {
    if(b>=c)
    {
     printf("\n Descending order : %d %d %d",a,b,c);
     printf("\n Ascending order : %d %d %d",c,b,a);
    }
    else
    {
     printf("\n Descending order : %d %d %d",a,c,b);
     printf("\n Ascending order : %d %d %d",b,c,a);
    }
 }
 else if((b>=a)&&(b>=c))
 {
    if(a>=c)
    {
     printf("\n Descending order : %d %d %d",b,a,c);
     printf("\n Ascending order : %d %d %d",c,a,b);
    }
    else
    {
     printf("\n Descending order : %d %d %d",b,c,a);
     printf("\n Ascending order : %d %d %d",a,c,b);
    }
 }
 else if((c>=a)&&(c>=b))
 {
  if(a>=b)
  {
     printf(" Descending order : %d %d %d",c,a,b);
     printf(" Ascending order : %d %d %d",b,a,c);
  }
  else
  {
     printf(" Descending order : %d %d %d",c,b,a);
     printf(" Ascending order : %d %d %d",a,b,c);
  }
}
 getch();
}

020. Write a program to accept two numbers from user and compare them in C language

#include<stdio.h>
#include<conio.h>
main()
{
 int a,b;
 clrscr();
 printf("Enter numbers...");
 scanf("%d%d",&a,&b);
 if(a>b)
	printf("a is greater than b");
 else if(b>a)
	printf("b is greater than a");
 else
	printf("both are equal");
 getch();
}

019. Write a program to accept a number from user and print if it is multiple of 7 in C language

#include<stdio.h>
#include<conio.h>
main()
{
 int n;
 clrscr();
 printf("Enter number...");
 scanf("%d",&n);
 if(n%7==0)
	printf("Number is multiple of 7");
 else
	printf("Number is not multiple of 7");
 getch();
}

018. Write a program to accept a number from user and print if it is divisible by 5 in C language

#include<stdio.h>
#include<conio.h>
main()
{
 int n;
 clrscr();
 printf("Enter number...");
 scanf("%d",&n);
 if(n%5==0)
	printf("Number is divisible by 5.");
 else
	printf("Number is not divisible by 5.");
 getch();
}

017. Write a program to accept a number from user and print if it is even or odd in C language

#include<stdio.h>
#include<conio.h>
main()
{
 int n;
 clrscr();
 printf("Enter number...");
 scanf("%d",&n);
 if(n%2==0)
	printf("Number is even...");
 else
	printf("Number is odd....");
 getch();
}

016. Write a program to accept a number and check if it is >10, <10 or =10 in C language

#include<stdio.h>
#include<conio.h>
main()
{
  int n;
  clrscr();
  printf("enter number...");
  scanf("%d",&n);
  if(n>10)
	printf("Number is greater than 10");
  else if(n<10)
	printf("Number is lesser than 10");
  else
	printf("Number is 10");
  getch();
}