while statement

THis almost works, but i'm stuck. It terminates, I want it after the user does a problem, returns to the top list.

Code:

#include <ctype.h>
#include <stdio.h>
#include <math.h>

int main()
     
{
  float addition, add1, add2, add3;
  float subtract, sub1, sub2;
  float multiply, mult1, mult2, mult3;
  float division, div1, div2;
  float modulate, smod1, smod2;
  char E, choice;

  do
    {
  printf("Please type in one of the following letters:");
  printf("\nA to add  three numbers: ");
  printf("\nS to Subtract two numbers: ");
  printf("\nM to Multiply three number: ");
  printf("\nD to Divide two number: ");
  printf("\nO to Modulate two number: ");
  printf("\nE to Exit program: ");
  printf("\n>:\n");
  scanf("%c", &choice);
  fflush(0);
  choice=toupper(choice);
    }while (choice != 'A' && choice != 'S' && choice != 'M' && choice != 'D' && choice != 'O' && choice != 'E');
 
  switch (choice)

     {
    case 'A':
     printf("\nPlease type the first number: ");
     scanf("%f", &add1);
     printf("\nPlease type the second number: ");
     scanf("%f", &add2);
     printf("\nPlease type the third number: ");
     scanf("%f", &add3);
     addition = add1+add2+add3;
     printf("%.2f + %.2f + %.2f equals %.2f\n", add1, add2, add3, addition);
     break;
 
   case 'S':
     printf("\nPlease type the first number: ");
     scanf("%f", &sub1);
     printf("\nPlease type the second number: ");
     scanf("%f", &sub2);
     subtract = sub1-sub2;
     printf("%.2f minus %.2f equals %.2f\n", sub1, sub2, subtract);
     break;
 
   case 'M':
     printf("\nPlease type the first number: ");
     scanf("%f", &mult1);
     printf("\nPlease type the second number: ");
     scanf("%f", &mult2);
     printf("\nPlease type the third number: ");
     scanf("%f", &mult3);
     multiply = mult1*mult2*mult3;
     printf("%.2f x %.2f x %.2f = %.2f\n", mult1, mult2, mult3, multiply);
     break;

    case 'D':
     printf("\nPlease type the first number: ");
     scanf("%f", &div1);
     printf("\nPlease type the second number: ");
     scanf("%f", &div2);
     division = div1/div2;
     printf("%.2f divided by %.2f equals %.2f\n\n", div1, div2, division);
     break;

   case 'O':
     printf("\nPlease type the first number: ");
     scanf("%f", &smod1);
     printf("\nPlease type the second number: ");
     scanf("%f", &smod2);
     modulate = fmod(smod1, smod2); 
     printf("The modulus of %.2f and %.2f leaves a remainder of %.2f\n\n", smod1, smod2, modulate);
     break;

   case 'E':
     printf("\n\nThank You and Goodbye!: %c", E);
     scanf("%c", &E);
     break;

    default:
      printf("\nInvalid choice, please try again");
      fflush(0);
      choice=toupper(choice);
  }
  return 0;
}

PS: This is the format we have to use that our instructer told us.

You need a second while() / do...while() loop on the outside of your code while (choice != 'E').

under default: choice=toupper(choice) is redundant, not needed, and repeatitive.

Code:

fflush(0);

Ohhhhh fflush used only for clearing/flushing the output buffer(standard) not the input buffer. See FAQ

ssharish2005

Originally Posted by ssharish2005

Code:

fflush(0);

Ohhhhh fflush used only for clearing/flushing the output buffer(standard) not the input buffer. See FAQ

ssharish2005

this is what he told us to use and how he said to use it

Originally Posted by wonderpoop

this is what he told us to use and how he said to use it

It's just fine. We see more fflush(stdin);'s than we can shake a stick at -- sometimes we miss ones like these and lump them in with the wrong crowd.

[edit]On the downside, your instructor is still having you take user input with scanf. So it makes such conclusions more likely. I wish it would be avoided.

Originally Posted by Dave_Sinkula

It's just fine. We see more fflush(stdin);'s than we can shake a stick at -- sometimes we miss ones like these and lump them in with the wrong crowd.

[edit]On the downside, your instructor is still having you take user input with scanf. So it makes such conclusions more likely. I wish it would be avoided.

this while statement is killing me, i tried it at the end, but it doesn't work right still. I can't think of any other while statement to put at the end, because it works better at the beginning. I put the fflush at the end with the choice=toupper(choice). Now if i type in the wrong letter i get the top menu, but if i type in the right letter it gives me the choice, but then exits. I want the user to exit only when they hit 'E'.

At the risk of the lambasting that will follow...

Code:

#include <ctype.h>
#include <stdio.h>
#include <math.h>

int main()
{
   float addition, add1, add2, add3;
   float subtract, sub1, sub2;
   float multiply, mult1, mult2, mult3;
   float division, div1, div2;
   float modulate, smod1, smod2;
   char E, choice;

   for ( ;; )
   {
      printf("Please type in one of the following letters:");
      printf("\nA to add  three numbers: ");
      printf("\nS to Subtract two numbers: ");
      printf("\nM to Multiply three number: ");
      printf("\nD to Divide two number: ");
      printf("\nO to Modulate two number: ");
      printf("\nE to Exit program: ");
      printf("\n>:\n");
      scanf("%c", &choice);
      fflush(0);
      choice=toupper(choice);

      switch ( choice )
      {
      case 'A':
         printf("\nPlease type the first number: ");
         scanf("%f", &add1);
         printf("\nPlease type the second number: ");
         scanf("%f", &add2);
         printf("\nPlease type the third number: ");
         scanf("%f", &add3);
         addition = add1+add2+add3;
         printf("%.2f + %.2f + %.2f equals %.2f\n", add1, add2, add3, addition);
         break;

      case 'S':
         printf("\nPlease type the first number: ");
         scanf("%f", &sub1);
         printf("\nPlease type the second number: ");
         scanf("%f", &sub2);
         subtract = sub1-sub2;
         printf("%.2f minus %.2f equals %.2f\n", sub1, sub2, subtract);
         break;

      case 'M':
         printf("\nPlease type the first number: ");
         scanf("%f", &mult1);
         printf("\nPlease type the second number: ");
         scanf("%f", &mult2);
         printf("\nPlease type the third number: ");
         scanf("%f", &mult3);
         multiply = mult1*mult2*mult3;
         printf("%.2f x %.2f x %.2f = %.2f\n", mult1, mult2, mult3, multiply);
         break;

      case 'D':
         printf("\nPlease type the first number: ");
         scanf("%f", &div1);
         printf("\nPlease type the second number: ");
         scanf("%f", &div2);
         division = div1/div2;
         printf("%.2f divided by %.2f equals %.2f\n\n", div1, div2, division);
         break;

      case 'O':
         printf("\nPlease type the first number: ");
         scanf("%f", &smod1);
         printf("\nPlease type the second number: ");
         scanf("%f", &smod2);
         modulate = fmod(smod1, smod2); 
         printf("The modulus of %.2f and %.2f leaves a remainder of %.2f\n\n", smod1, smod2, modulate);
         break;

      case 'E':
         printf("\n\nThank You and Goodbye!: %c", E);
         scanf("%c", &E);
         goto done;

      default:
         printf("\nInvalid choice, please try again");
         fflush(0);
         choice=toupper(choice);
      }
   }
done:
   return 0;
}

Breaking a loop from a switch is one of the few places where a goto may be the better candidate.

Let the argument ensue...

Heh, personally I agree with you, but I have to wonder (and I'd wonder with my compiler if I had it handy)...what if you initalized choice to anything other than 'E', made (choice != 'E') the condition of the for loop, and used continue instead of goto?

[edit] Or, of course, the do-while loop that was originally suggested? It helps to read the whole thread.

Originally Posted by Dave_Sinkula

At the risk of the lambasting that will follow...

Code:

#include <ctype.h>
#include <stdio.h>
#include <math.h>

int main()
{
   float addition, add1, add2, add3;
   float subtract, sub1, sub2;
   float multiply, mult1, mult2, mult3;
   float division, div1, div2;
   float modulate, smod1, smod2;
   char E, choice;

   for ( ;; )
   {
      printf("Please type in one of the following letters:");
      printf("\nA to add  three numbers: ");
      printf("\nS to Subtract two numbers: ");
      printf("\nM to Multiply three number: ");
      printf("\nD to Divide two number: ");
      printf("\nO to Modulate two number: ");
      printf("\nE to Exit program: ");
      printf("\n>:\n");
      scanf("%c", &choice);
      fflush(0);
      choice=toupper(choice);

      switch ( choice )
      {
      case 'A':
         printf("\nPlease type the first number: ");
         scanf("%f", &add1);
         printf("\nPlease type the second number: ");
         scanf("%f", &add2);
         printf("\nPlease type the third number: ");
         scanf("%f", &add3);
         addition = add1+add2+add3;
         printf("%.2f + %.2f + %.2f equals %.2f\n", add1, add2, add3, addition);
         break;

      case 'S':
         printf("\nPlease type the first number: ");
         scanf("%f", &sub1);
         printf("\nPlease type the second number: ");
         scanf("%f", &sub2);
         subtract = sub1-sub2;
         printf("%.2f minus %.2f equals %.2f\n", sub1, sub2, subtract);
         break;

      case 'M':
         printf("\nPlease type the first number: ");
         scanf("%f", &mult1);
         printf("\nPlease type the second number: ");
         scanf("%f", &mult2);
         printf("\nPlease type the third number: ");
         scanf("%f", &mult3);
         multiply = mult1*mult2*mult3;
         printf("%.2f x %.2f x %.2f = %.2f\n", mult1, mult2, mult3, multiply);
         break;

      case 'D':
         printf("\nPlease type the first number: ");
         scanf("%f", &div1);
         printf("\nPlease type the second number: ");
         scanf("%f", &div2);
         division = div1/div2;
         printf("%.2f divided by %.2f equals %.2f\n\n", div1, div2, division);
         break;

      case 'O':
         printf("\nPlease type the first number: ");
         scanf("%f", &smod1);
         printf("\nPlease type the second number: ");
         scanf("%f", &smod2);
         modulate = fmod(smod1, smod2); 
         printf("The modulus of %.2f and %.2f leaves a remainder of %.2f\n\n", smod1, smod2, modulate);
         break;

      case 'E':
         printf("\n\nThank You and Goodbye!: %c", E);
         scanf("%c", &E);
         goto done;

      default:
         printf("\nInvalid choice, please try again");
         fflush(0);
         choice=toupper(choice);
      }
   }
done:
   return 0;
}

Breaking a loop from a switch is one of the few places where a goto may be the better candidate.

Let the argument ensue...

It has to be a do while statement. I don't even know anything about goto done yet. If you test the program you will see is no problem breaking the loop, since i can't get one to work yet anyways

Originally Posted by wonderpoop

It has to be a do while statement. I don't even know anything about goto done yet. If you test the program you will see is no problem breaking the loop, since i can't get one to work yet anyways

There's no loop to break, thus "no problem".

You want the menu in a loop -- including the action -- right? Put it in a loop.

Originally Posted by Dave_Sinkula

There's no loop to break, thus "no problem".

You want the menu in a loop, right? Put it in a loop.

That's what the while statement is for. If i type in the wrong letter, it goes back to the menu just fine. But i can't figure out how to get it to go back to that same menu each time the person types in ASMDO does the problem, then back to the menu, unless they type E for exit and it exits the program.

*sigh*

The "whole thing in a loop".

Code:

 do
   {
      printf("Please type in one of the following letters:");
      printf("\nA to add  three numbers: ");
      printf("\nS to Subtract two numbers: ");
      printf("\nM to Multiply three number: ");
      printf("\nD to Divide two number: ");
      printf("\nO to Modulate two number: ");
      printf("\nE to Exit program: ");
      printf("\n>:\n");
      scanf("%c", &choice);
      fflush(0);
      choice=toupper(choice);

      if ( choice == 'E' )
      {
         puts("\n\nThank You and Goodbye!");
         break;
      }

      switch ( choice )
      {
      case 'A':
         printf("\nPlease type the first number: ");
         scanf("%f", &add1);
         printf("\nPlease type the second number: ");
         scanf("%f", &add2);
         printf("\nPlease type the third number: ");
         scanf("%f", &add3);
         addition = add1+add2+add3;
         printf("%.2f + %.2f + %.2f equals %.2f\n", add1, add2, add3, addition);
         break;

      case 'S':
         printf("\nPlease type the first number: ");
         scanf("%f", &sub1);
         printf("\nPlease type the second number: ");
         scanf("%f", &sub2);
         subtract = sub1-sub2;
         printf("%.2f minus %.2f equals %.2f\n", sub1, sub2, subtract);
         break;

      case 'M':
         printf("\nPlease type the first number: ");
         scanf("%f", &mult1);
         printf("\nPlease type the second number: ");
         scanf("%f", &mult2);
         printf("\nPlease type the third number: ");
         scanf("%f", &mult3);
         multiply = mult1*mult2*mult3;
         printf("%.2f x %.2f x %.2f = %.2f\n", mult1, mult2, mult3, multiply);
         break;

      case 'D':
         printf("\nPlease type the first number: ");
         scanf("%f", &div1);
         printf("\nPlease type the second number: ");
         scanf("%f", &div2);
         division = div1/div2;
         printf("%.2f divided by %.2f equals %.2f\n\n", div1, div2, division);
         break;

      case 'O':
         printf("\nPlease type the first number: ");
         scanf("%f", &smod1);
         printf("\nPlease type the second number: ");
         scanf("%f", &smod2);
         modulate = fmod(smod1, smod2); 
         printf("The modulus of %.2f and %.2f leaves a remainder of %.2f\n\n", smod1, smod2, modulate);
         break;

         /* note stuff not here */

      default:
         printf("\nInvalid choice, please try again");
         fflush(0);
      }
   } while(1);

Originally Posted by Dave_Sinkula

*sigh*

The "whole thing in a loop".

Code:

 do
   {
      printf("Please type in one of the following letters:");
      printf("\nA to add  three numbers: ");
      printf("\nS to Subtract two numbers: ");
      printf("\nM to Multiply three number: ");
      printf("\nD to Divide two number: ");
      printf("\nO to Modulate two number: ");
      printf("\nE to Exit program: ");
      printf("\n>:\n");
      scanf("%c", &choice);
      fflush(0);
      choice=toupper(choice);

      if ( choice == 'E' )
      {
         puts("\n\nThank You and Goodbye!");
         break;
      }

      switch ( choice )
      {
      case 'A':
         printf("\nPlease type the first number: ");
         scanf("%f", &add1);
         printf("\nPlease type the second number: ");
         scanf("%f", &add2);
         printf("\nPlease type the third number: ");
         scanf("%f", &add3);
         addition = add1+add2+add3;
         printf("%.2f + %.2f + %.2f equals %.2f\n", add1, add2, add3, addition);
         break;

      case 'S':
         printf("\nPlease type the first number: ");
         scanf("%f", &sub1);
         printf("\nPlease type the second number: ");
         scanf("%f", &sub2);
         subtract = sub1-sub2;
         printf("%.2f minus %.2f equals %.2f\n", sub1, sub2, subtract);
         break;

      case 'M':
         printf("\nPlease type the first number: ");
         scanf("%f", &mult1);
         printf("\nPlease type the second number: ");
         scanf("%f", &mult2);
         printf("\nPlease type the third number: ");
         scanf("%f", &mult3);
         multiply = mult1*mult2*mult3;
         printf("%.2f x %.2f x %.2f = %.2f\n", mult1, mult2, mult3, multiply);
         break;

      case 'D':
         printf("\nPlease type the first number: ");
         scanf("%f", &div1);
         printf("\nPlease type the second number: ");
         scanf("%f", &div2);
         division = div1/div2;
         printf("%.2f divided by %.2f equals %.2f\n\n", div1, div2, division);
         break;

      case 'O':
         printf("\nPlease type the first number: ");
         scanf("%f", &smod1);
         printf("\nPlease type the second number: ");
         scanf("%f", &smod2);
         modulate = fmod(smod1, smod2); 
         printf("The modulus of %.2f and %.2f leaves a remainder of %.2f\n\n", smod1, smod2, modulate);
         break;

         /* note stuff not here */

      default:
         printf("\nInvalid choice, please try again");
         fflush(0);
      }
   } while(1);

Now what happens if the user types in R?

Bad things. You're using scanf.

Fully uglified, this is what you are supposed to churn out (more or less).

Code:

#include <ctype.h>
#include <stdio.h>
#include <math.h>

int main()
{
   float addition, add1, add2, add3;
   float subtract, sub1, sub2;
   float multiply, mult1, mult2, mult3;
   float division, div1, div2;
   float modulate, smod1, smod2;
   char choice;
   int cleanup;

   do
   {
      puts("Please type in one of the following letters:");
      puts("A to add  three numbers: ");
      puts("S to Subtract two numbers: ");
      puts("M to Multiply three number: ");
      puts("D to Divide two number: ");
      puts("O to Modulate two number: ");
      puts("E to Exit program: ");
      printf(">:");
      fflush(stdout);
      scanf("%c", &choice);
      choice=toupper(choice);
      while ( (cleanup = getchar()) != '\n' && cleanup != EOF );

      if ( choice == 'E' )
      {
         puts("Thank You and Goodbye!");
         break;
      }

      switch ( choice )
      {
      case 'A':
         printf("Please type the first number: ");
         fflush(stdout);
         scanf("%f", &add1);
         while ( (cleanup = getchar()) != '\n' && cleanup != EOF );
         printf("Please type the second number: ");
         fflush(stdout);
         scanf("%f", &add2);
         while ( (cleanup = getchar()) != '\n' && cleanup != EOF );
         printf("Please type the third number: ");
         fflush(stdout);
         scanf("%f", &add3);
         while ( (cleanup = getchar()) != '\n' && cleanup != EOF );
         addition = add1+add2+add3;
         printf("%.2f + %.2f + %.2f equals %.2f\n", add1, add2, add3, addition);
         break;

      case 'S':
         printf("Please type the first number: ");
         fflush(stdout);
         scanf("%f", &sub1);
         while ( (cleanup = getchar()) != '\n' && cleanup != EOF );
         printf("Please type the second number: ");
         fflush(stdout);
         scanf("%f", &sub2);
         while ( (cleanup = getchar()) != '\n' && cleanup != EOF );
         subtract = sub1-sub2;
         printf("%.2f minus %.2f equals %.2f\n", sub1, sub2, subtract);
         break;

      case 'M':
         printf("Please type the first number: ");
         fflush(stdout);
         scanf("%f", &mult1);
         while ( (cleanup = getchar()) != '\n' && cleanup != EOF );
         printf("Please type the second number: ");
         fflush(stdout);
         scanf("%f", &mult2);
         while ( (cleanup = getchar()) != '\n' && cleanup != EOF );
         printf("Please type the third number: ");
         fflush(stdout);
         scanf("%f", &mult3);
         while ( (cleanup = getchar()) != '\n' && cleanup != EOF );
         multiply = mult1*mult2*mult3;
         printf("%.2f x %.2f x %.2f = %.2f\n", mult1, mult2, mult3, multiply);
         break;

      case 'D':
         printf("Please type the first number: ");
         fflush(stdout);
         scanf("%f", &div1);
         while ( (cleanup = getchar()) != '\n' && cleanup != EOF );
         printf("Please type the second number: ");
         fflush(stdout);
         scanf("%f", &div2);
         division = div1/div2;
         printf("%.2f divided by %.2f equals %.2f\n", div1, div2, division);
         break;

      case 'O':
         printf("Please type the first number: ");
         fflush(stdout);
         scanf("%f", &smod1);
         while ( (cleanup = getchar()) != '\n' && cleanup != EOF );
         printf("Please type the second number: ");
         fflush(stdout);
         scanf("%f", &smod2);
         while ( (cleanup = getchar()) != '\n' && cleanup != EOF );
         modulate = fmod(smod1, smod2); 
         printf("The modulus of %.2f and %.2f leaves a remainder of %.2f\n", smod1, smod2, modulate);
         break;

      default:
         puts("Invalid choice, please try again");
         fflush(stdout);
      }
   } while ( 1 );
   return 0;
}

Happy bad coding. Let's see if you get to the better ways and can get away with it.