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 descending order in C language

  #include<stdio.h>
  void main()
  {
      int a,b,c;
  
      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("\n Descending order : %d %d %d",c,a,b);
              printf("\n Ascending order : %d %d %d",b,a,c);
          }
          else
          {
              printf("\n Descending order : %d %d %d",c,b,a);
              printf("\n Ascending order : %d %d %d",a,b,c);
          }
      }
  }
  

• 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();
  }