switch_case_not_working :S

hi, i want to make a calculator. ive done it before but now after some years i come back to c++ and it doesnt work
here my code

Code:

#include <iostream.h>

int main()
{
	char option[1];
	cout<<"Welcome to PicoCalc ;0)"<<'\n';
	cout<<"Choose your function: +,-,* or /"<<'\n';

	cin>>option;
	switch(option);
	{
	case '+':
		cout<<"Enter first number:"<<'\n';
		int num1;
		cin>>num1;
		cout<<"Enter second number:"<<'\n';
		int num2;
		cout<<"Result is "<<num1+num2<<'\n';
		break;
	case '-':
		cout<<"Enter first number:"<<'\n';
		int num1;
		cin>>num1;
		cout<<"Enter second number:"<<'\n';
		int num2;
		cout<<"Result is "<<num1-num2<<'\n';
		break;
	case '*':
		cout<<"Enter first number:"<<'\n';
		int num1;
		cin>>num1;
		cout<<"Enter second number:"<<'\n';
		int num2;
		cout<<"Result is "<<num1*num2<<'\n';
		break;
	case '/':
		cout<<"Enter first number:"<<'\n';
		int num1;
		cin>>num1;
		cout<<"Enter second number:"<<'\n';
		int num2;
		cout<<"Result is "<<num1/num2<<'\n';
		break;
	default:
		cout<<"Invalid choise!"<<'\n';
	}

	cout<<"test";			//here i will put option to make another calculation..

	return (0);
}

i compile using visual c++ and get following errors:

Code:

C:\Documents and Settings\user\Desktop\example4\example4.cpp(14) : error C2450: switch expression of type 'char [1]' is illegal
        Integral expression required
C:\Documents and Settings\user\Desktop\example4\example4.cpp(14) : warning C4060: switch statement contains no 'case' or 'default' labels
C:\Documents and Settings\user\Desktop\example4\example4.cpp(16) : error C2046: illegal case
C:\Documents and Settings\user\Desktop\example4\example4.cpp(23) : error C2043: illegal break
C:\Documents and Settings\user\Desktop\example4\example4.cpp(24) : error C2046: illegal case
C:\Documents and Settings\user\Desktop\example4\example4.cpp(26) : error C2086: 'num1' : redefinition
C:\Documents and Settings\user\Desktop\example4\example4.cpp(29) : error C2086: 'num2' : redefinition
C:\Documents and Settings\user\Desktop\example4\example4.cpp(31) : error C2043: illegal break
C:\Documents and Settings\user\Desktop\example4\example4.cpp(32) : error C2046: illegal case
C:\Documents and Settings\user\Desktop\example4\example4.cpp(34) : error C2086: 'num1' : redefinition
C:\Documents and Settings\user\Desktop\example4\example4.cpp(37) : error C2086: 'num2' : redefinition
C:\Documents and Settings\user\Desktop\example4\example4.cpp(39) : error C2043: illegal break
C:\Documents and Settings\user\Desktop\example4\example4.cpp(40) : error C2046: illegal case
C:\Documents and Settings\user\Desktop\example4\example4.cpp(42) : error C2086: 'num1' : redefinition
C:\Documents and Settings\user\Desktop\example4\example4.cpp(45) : error C2086: 'num2' : redefinition
C:\Documents and Settings\user\Desktop\example4\example4.cpp(47) : error C2043: illegal break
C:\Documents and Settings\user\Desktop\example4\example4.cpp(48) : error C2047: illegal default
Error executing cl.exe.

example4.exe - 16 error(s), 1 warning(s)

any ideas?
cheers

ok , lets start cleaning up this mess :

Code:

#include <iostream.h>

Although its not an error , but you're following the old C++ standard. The new way to do this is either :

Code:

#include <iostream>
using namespace std;

or better :

Code:

#include <iostream>
using std::cout;
using std::cin;

The second option is recommended to avoid naming conflicts , not a biggie though.

Code:

char option[1];

If you're going to store one character only , then why didn't you just declare a regular character instead of a one-character-array?

This messed up the switch statement because 'option' has the memory adress of the first element of your array , whereas 'option[0]' has the first value (remember when referring to elements you start counting from 0).

Your switch statement took a memory adress instead of a value , therefore none of the cases matched it. But wait !! did the switch statement even work? no. Becuase you terminated it right away with a semi-colon here :

Code:

switch(option);
	{

if you remove that semi-colon you'll get rid of some of the errors. If you still insist on using s single character array though , just replace the input with 'cin >> option[0];' and use 'option[0]' within the switch statement.



This error :

'num1' : redefinition

showed up because you defined 'num1' more than once. You should've defined num1 and num2 before the switch statement then use them within the cases.


another error here :

Code:

cout<<"Enter second number:"<<'\n';
		int num2;

Seems like you typed 'int' instead of 'cin >>' by mistake. But you repeated that with the rest of the cases.

fix those errors and your program should work again.


Here's a big hint : read what the error(s) say

hi thx ur reply mate.
i read wat the errors said, but just "illegal case/break" etc didnt give me any tip. obviously there was a problem with the switch statement, i'll remove the colon and it should be fine

You're defining variables inside the case statement. You can't in general do that.
For instance, if you have

Code:

switch(a) {
case 5:
     int c;
case 6:
     int d;
     c = 5;
}

Whether c = 5 in case 6 makes "sense" is whether case 5 dropped into case 6. But C++ determines scope statically. If you really need to define variables within the cases, you can do

Code:

switch(a) {
case 4: 
{
      int c;
}

}

But this, looks ugly. Your're better off either defining the variables outside of the switch statement or creating a new function.