Program 173:Calculate Simple Interest in all Ways

Program 173:             Learn Switch case in detail
 

#include<stdio.h>
main()
{ 
  float p,r,t,simpleInterest;
  int choice;
  printf("Enter\n1 to find out Simple Interest\n2 to find out Principal\n3 to find out rate in % \n4 to find out Time\n");
  scanf("%d",&choice);
  switch(choice)
  {
   case 1:
   {
   printf("Enter Pricipal\n");
    scanf("%f",&p);
    printf("Enter Rate in percentage \n");
    scanf("%f",&r);
    printf("Enter Time in years(decimals)\n");
    scanf("%f",&t);
    
    simpleInterest=(float)(p*r*t)/100.0;
    printf("Simple Interest is %f\n",simpleInterest);
    break;
   }
   case 2:
   {
   printf("Enter Simple Interest\n");
    scanf("%f",&simpleInterest);
    printf("Enter Rate in percentage\n");
    scanf("%f",&r);
    printf("Enter Time in years(decimals)\n");
    scanf("%f",&t);
    p=(float)(100.0*simpleInterest)/(r*t);
    printf("Principal is %f\n",p);
    break;
    
     }
     case 3:
     {
   printf("Enter Simple Interest\n");
    scanf("%f",&simpleInterest);
    printf("Enter Principal\n");
    scanf("%f",&p);
    printf("Enter Time in years(decimals)\n");
    scanf("%f",&t);
    r=(float)(100.0*simpleInterest)/(p*t);
    printf("Rate is %f%\n",r);
    break;
     }
     case 4:
     {
   printf("Enter Simple Interest\n");
    scanf("%f",&simpleInterest);
    printf("Enter Principal\n");
    scanf("%f",&p);
    printf("Enter Rate in percentage\n");
    scanf("%f",&r);
    t=(float)((100.0*simpleInterest)/(p*r));
    printf("Time is %f years\n",t);
      break;
     }
  }
}

Explanation:
Formulae used in Program:

1.Simple Interest=(Principal*Rate in %* Time in Years)/100

2.Principal=(100*Simple Interest)/(Rate in %* Time in Years)

3.Rate(%)=(100*Simple Interest)/(Principal* Time in Years)

4.Time(Yrs)=(100*Simple Interest)/(Principal* Rate(%)) 

1. This program starts with initializing :
   • p → To store principal in Rupees
   • r → To store rate in %
   • t → To store time in years
   • simpleInterest → To store output

2. printf("Enter\n1 to find out Simple Interest\n2 to find out Principal\n
   3 to find out rate in % \n4 to find out Time\n");
     scanf("%d",&choice);

   To prompt user to choose one of the following as shown in the output.
3. Lets run by giving choice as 2 which is to find out Principal.
4. As the choice is 2. Case 2: will be executed. Learn Switch case in detail
   • As per case formula 2 is used for execution

   •  printf("Enter Simple Interest\n");
         scanf("%f",&simpleInterest);

     Taking Simple Interest from user
     

         printf("Enter Rate in percentage\n");
         scanf("%f",&r);

     Taking Rate from user

         printf("Enter Time in years(decimals)\n");
         scanf("%f",&t);

     Taking Time from user

         p=(float)(100.0*simpleInterest)/(r*t);
         printf("Principal is %f\n",p);
         break;

     From formula 2 the above will calculate and stores result in p which is then printed.

Output: