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 :confused:
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 :

Quote:

---

'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.