What is wrong with this Switch statement???????

BaRcOe

#include <stdio.h>
main()
{
char operator ;
float num1, num2, answer ;

printf("Please enter an arithmetic expression (e.g. 1 + 2) " ) ;
scanf ( "%f%1s%f", &num1, &operator, &num2 ) ;

switch ( operator )
{
case '+' :
answer = num1 + num2 ;
printf( "%f plus %f equals %f\n", num1, num2, answer ) ;
break ;
case '-' :
answer = num1 - num2 ;
printf( "%f minus %f equals %f\n", num1, num2, answer ) ;
break ;
case '*':
answer = num1 * num2 ;
printf ( "%f multiplied by %f equals %f\n", num1, num2, answer ) ;
break ;
case '/' :
answer = num1 / num2 ;
printf("%f divided by %f equals %f\n", num1, num2, answer ) ;
break ;
default:
printf("Invalid operator\n") ;
}
}

7 Errors
Error E2076 calculator.c 6: Overloadable operator expected in function main()
Error E2139 calculator.c 7: Declaration missing ; in function main()
Error E2451 calculator.c 10: Undefined symbol 'num1' in function main()
Error E2451 calculator.c 10: Undefined symbol ',' in function main()
Error E2451 calculator.c 10: Undefined symbol 'num2' in function main()
Error E2076 calculator.c 12: Overloadable operator expected in function main()
Error E2377 calculator.c 13: Switch statement missing ) in function main()

Tobias Greeshman

That code compiles just fine in gcc on linux.

What compiler did you try and compile this on?

Peadar06

#include <stdio.h>
main()
{
char option ;
float num1, num2, answer ;

printf("\nPlease enter an arithmetic expression (e.g. 1 + 2)\n" ) ;
scanf ( "%f%1s%f", &num1, &option, &num2 ) ;

switch ( option )
{
case '+' :
answer = num1 + num2 ;
printf( "%.2f plus %.2f equals %.2f\n", num1, num2, answer ) ;
break ;

case '-' :
answer = num1 - num2 ;
printf( "%.2f minus %.2f equals %.2f\n", num1, num2, answer ) ;
break ;

case '*':
case 'x':
case 'X':
answer = num1 * num2 ;
printf ( "%.2f multiplied by %.2f equals %.2f\n", num1, num2, answer ) ;
break ;

case '/' :
answer = num1 / num2 ;
printf("%.2f divided by %.2f equals %.2f\n", num1, num2, answer ) ;
break ;

default:
printf("Invalid operator\n") ;
}
}

This works compiles perfectly now in Borland C++ and Dev C++, you originally had "char operator ;", which can't be used as operator is a key word in C programming. I hope this is of some help to you.

Peter

Boxman

The switch statement is fine but assuming you are using a c++ compiler you need to rename your operator variable to something else as 'operator' is a reserved keyword in c++.

Peadar06

Yes of course, that is true, that is the reason that I changed operator to option.

Peter

Boxman

I didn't see your post Peadar - You just beat me to it! :-)

Boxman

Also OP there is another problem - with your scanf line.

scanf ( "%f%1s%f", &num1, &operator, &num2 ) ;

You are attempting to copy a string of length 1 into your 'operator' variable. Your 'operator' variable only occupies 1 char of space in memory.

Leaving the name 'operator' as it is for the moment, the string of length 1 will actually take up 2 chars of space - 1 char for the user inputted '+' or whatever, and 1 char for the '\0' special char which terminates the string.

Now 2 into 1 wont go which results in memory after the address of the 'operator' variable being overwritten.

While you might be lucky and not see any side effects, it is a crash waiting to happen and can lead to unpredictable behaviour. e.g. Segmentation faults.

So , you should rename your 'operator' variable to 'option' (if using a c++ compiler), and allocate 2 chars for it. i.e

char option[2].

Change your scanf line to

scanf ( "%f%1s%f", &num1, option, &num2 ) ;
(the name of an array is in fact a pointer to the first location)

and 'switch' on the first element.

switch (option[0])

Evil Phil

OP have a read of the forum charter please, and next time could you make an effort to explain the problem you are experiencing instead of just posting the code, the errors and getting somebody else to do your homework for you.

BaRcOe

Evil Phil wrote: »

OP have a read of the forum charter please, and next time could you make an effort to explain the problem you are experiencing instead of just posting the code, the errors and getting somebody else to do your homework for you.

Sorry im new to C thats all. it was just me trying to get used of switch statements, not homework, ill try be more specific from now on?

BaRcOe

Evil Phil wrote: »

OP have a read of the forum charter please, and next time could you make an effort to explain the problem you are experiencing instead of just posting the code, the errors and getting somebody else to do your homework for you.

Homework & Learning to code: How to ask a question! (The Rules)

* Try and give a good description of your problem in the thread title.
* Post a sample of your code no matter how poor you may think it is. It shows an effort on your behalf and that's really important
* Try and explain your attempt in the previous point
* Now ask any questions you may have

I gave a sample of my code. I made an effort.
I showed my errors and got help. I thanked the posters for it and am satisfied

a warning is harsh

Evil Phil

Posting code, posting errors but not posting an explanation of what your problem is is just plain lazy. So you get a warning.

Complaining about that gets you banned.