A switch question

How do I do this:

Code:

---

string test;
test = "hey";

switch(test)
{
case "bye": do somthing();
case "hey": do somthing();
}

---

i get a [C++ Error] Unit1.cpp(25): E2383 Switch selection expression must be of integral type error. any help would be nice! :D
thx

DW

the controlling expression for a switch statement must always return either a bool value or an enum constant - one of integer type or character.

... and don't forget the "break" statement.

Here's how I do it:

Code:

---

#define STR_STRING1 "string1"
#define STR_STRING2 "string2"

int WhatStringIsThis(char *TheString)
{
    if (!strcmpi(TheString,STR_STRING1))
        return STR_STRING1;
    if (!strcmpi(TheString,STR_STRING2))
        return STR_STRING2;

    return 0;
}

int main()
{
    char Input[32];

    cin >> Input;

    switch (WhatStringIsThis((char *)&Input))
    {
        case STR_STRING1:
            //etc

---

That seems to me like the only way to do it with a switch.

Quote:

---

Originally Posted by bennyandthejets

Here's how I do it:

Code:

---

#define STR_STRING1 "string1"
#define STR_STRING2 "string2"

int WhatStringIsThis(char *TheString)
{
    if (!strcmpi(TheString,STR_STRING1))
        return STR_STRING1;
    if (!strcmpi(TheString,STR_STRING2))
        return STR_STRING2;

    return 0;
}

int main()
{
    char Input[32];

    cin >> Input;

    switch (WhatStringIsThis((char *)&Input))
    {
        case STR_STRING1:
            //etc

---

That seems to me like the only way to do it with a switch.

---

no, that won't work! that macro still reduces to a character array - in this type of situation, just use if/else statements.

how bout going this route?

Code:

---

#define "Wood" 7777;
#define "Stone" 6666;
#define "Me" 9999;

//get variable

cin << K;

//then could you switch on the k?

switch(k)
{
case 7777: break;
case 6666: break;
}

---

is this okay?

Nope. There is no easy way to use a switch on a string of characters.

And besides cin has no operator <<

Quote:

---

Originally Posted by Death_Wraith

how bout going this route?

Code:

---

#define "Wood" 7777;
#define "Stone" 6666;
#define "Me" 9999;
//get variable
cin << K;
//then could you switch on the k?
switch(k)
{
case 7777: break;
case 6666: break;
}

---

is this okay?

---

no, it's not ok. ;)

you're missing the point. the switch statement is solely for testing against integral manifest constants - trying to work string handling in there is just a waste of your time...

Oops sorry I mucked up that method. Here is the correct way:

Code:

---

#define STR_STRING1 101
#define STR_STRING2 102

int WhatStringIsThis(char *TheString)
{
    if (!strcmpi(TheString,"string1"))
        return STR_STRING1;
    if (!strcmpi(TheString,"string2"))
        return STR_STRING2;

    return 0;
}

int main()
{
    char Input[32];

    cin >> Input;

    switch (WhatStringIsThis((char *)&Input))
    {
        case STR_STRING1:
            //etc

---

I know it's messy but if you insist on using a switch, it's alright.

Quote:

---

Originally Posted by Thantos

Nope. There is no easy way to use a switch on a string of characters.

And besides cin has no operator <<

---

hahahah oops!
:confused:

Alright, so its not worth my time then?

Not really. The easiest method is

Code:

---

switch (true)
{
        case (test == "hey"):
                DoSomething();
                break;
        case (test == "bye"):
                DoSomethingElse();
                break;
}

---

but then you might as well use if/else if.

Did you even try and test that MortalMonkey? cases in a switch MUST be constant. Which means no evaluation may be done to determine a case's value.

w00t for BASIC's "Select Case" statement :D

try reducing the string to an integer using a map

How would I use a map?

>>try reducing the string to an integer using a map

IMO that would just complicate things even more, and I don't know if it would be very efficient either. I think it's just as simple to do:

Code:

---

#include <iostream>

#define STR1 "String1"
#define STR2 "String2"
int main()
{
  std::string test;
  std::cin>>test;
  if (test==STR1)
    //do something
  else if (test==STR2)
    //do something else

}

---

That's not too hard to read is it?

but what if you have a LOT OF STRINGS@#%

huh, your not considering the full impliciations and possibliities of each situation
huh

huh, if he doesn't know that you can't switch a string do you think that he really needs to learn use a map for alot of strings
huh

yes
syntax is secondary to programming

i don't even invoke a compiler anymore, i just imagine my creations running perfectly

Quote:

---

#define STR1 "String1"
#define STR2 "String2"

---

Might want to make that:

Quote:

---

const std::string str1("String1");
const std::string str2("String2");

---

Just for the sake of not mixing C and C++ strings :)

I suppose so...Although I like to use defines so I can declare them in a header file to keep things a bit neater.

Couldn't you just create a singleton to encapsulate all the messy global variables, then declare the const strings in that?

**EDIT**
Actually, couldn't you just do this:

Code:

---

#define STRING1 std::string("String1")

---

Heh, not much to look at I guess...

Quote:

---

Couldn't you just create a singleton to encapsulate all the messy global variables, then declare the const strings in that?

---

I don't know, never used singleton for anything before.

>>Actually, couldn't you just do this:

I suppose so, but that would create a new string everything you used it. It seems kind of like an abuse of defines though, after all, the string class does have a comparison operator for cstrings, so why not use it?

>>the string class does have a comparison operator for cstrings, so why not use it?
Why would you, when you can have so much fun with confusing #define's that construct new objects of classes every time you use them? :D

Okay.....I think the point is this: There is NO way to use a switch with a string without complicating the hell out the programmer! lol So i guess I have to use an If/Else!

Quote:

---

Originally Posted by Thantos

Did you even try and test that MortalMonkey?

---

Only in UnrealScript. I'm starting to mix up the languages, it seems.