Using a string in C++ Switch case

Or better : you don't even seem to need a switch - you can use an array of strings together with the enum :

typedef enum ItemType {
  ITEM_INVALID = 0,
  ITEM_CRISPS = 1,
  ITEM_CHOCOLATE = 2,
  ITEM_LEMONADE = 3,
  ITEM_BISCUITS = 4
} ItemType;
 
static std::string itemName[] = {
  "Invalid selection",
  "Walkers Cheese & Onion",
  "Cadburys Dairy Milk",
  "Schweppes Lemonade",
  "McVities Digestives"
}
 
 
// and then :
 
ItemType input;            // put the item type in here
 
std::cout << itemName[input] << std::endl;

                                              

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Or still better would be to load the items at run time (from a file or database) into a vector of Item objects. The Item class would have the operator<< overloaded so that you can display its name (and/or a toString method or similar).

The enum und string array solution, Infinity showed could be improved:


enum ItemType
{
  ITEM_INVALID = -1,
  ITEM_CRISPS,
  ITEM_CHOCOLATE,
  ITEM_LEMONADE,
  ITEM_BISCUITS,
  ITEM_MAX
};

const char * szItemTypes[ITEM_MAX] =
{
  "Walkers Cheese & Onion",
  "Cadburys Dairy Milk",
  "Schweppes Lemonade",
  "McVities Digestives",
};

 ...
 string input;
 showMenu();
 cout << "Make your choice: ";
 getline(cout, input);
 int i = 0;
 for (; i < MAX_ITEM; ++i)
 {
     if (input == szItemsTypes[i])
     {
         switch(i)
         {
            case ITEM_CRISPS :
              cout << "Walkers Cheese & Onion" << endl;
              break;
           case ITEM_CHOCOLATE :
              cout << "Cadburys Dairy Milk" << endl;
              break;
           case ITEM_LEMONADE :
              cout << "Schweppes Lemonade" << endl;
           break;
              case ITEM_BISCUITS :
              cout << "McVities Digestives" << endl;
           break;
          }
     }
     if (i >= MAX_ITEM)
     {
        cout << "Invalid selection\n";
     }
 }

Remarks:

the 'typedef enum' is for C compatibility only. In C++ you can omit it and define it like a struct or class.

if you don't assign a number to enum constants, the constants were numbered automatically starting with 0 for the first constant with no value. That way the MAX_ITEM automatically counts the items - if always the last constant - and can be used for array size.

For static and const char arrays, the usage of std::string has no advantages. On the contrary you may experience that the debugger complains about memory leaks as the strings were freed at end of program.

I didn't use the ItemType as a type but an integer (int i). If the number was inputted or must be read from file or database, you can't guarantee at compile time that the number is a valid enum constant and would need to make a cast or even have an invalid enum.

Note, in the above scenario the user rarely will input the text but the number, so that you wouldn't need to make string comparision for input. You would use the strings to show the menu by outputting the enum constant and the corresponding string for each line.

>> The enum und string array solution, Infinity showed could be improved:

Everything can always be improved. The point was simply to show a quick example to get an idea of how this could be approached. Personally, I'd prefer the third approach I mentioned though.

Btw, to be honest, I wouldn't call this :

 for (; i < MAX_ITEM; ++i)
 {
     if (input == szItemsTypes[i])
     {
         switch(i)
         {

an improvement. Looping over all the items to find the one you need is a bit wasteful, while you might as well have sorted the strings, or placed them in a map, or ...

Everything can be improved ;)

>> For static and const char arrays, the usage of std::string has no advantages. On the contrary you may experience that the debugger complains about memory leaks as the strings were freed at end of program.
Actually, there is a more serious problem here in so far as a std::string is not a POD (Plain Old Data) type so it can throw an exception on construction, causing your application to crash without warning or any useful reason why -- this can be very hard to isolate. Stick to using C-Style strings for file/namespace scope variables.

Apart from that I am not seeing any improvement :)

Not quite sure why we need enums for this.

#include <iostream>
 
// Choices
char const * szChoices[] = 
{
	"Walkers Cheese & Onion",
	"Cadburys Dairy Milk",
	"Schweppes Lemonade",
	"McVities Digestives",
};
 
// Max number of choices
size_t MAX_ITEM = sizeof(szChoices)/sizeof(szChoices[0]);
 
int main()
{
	// Loop until user enters '0' to quit
	for(;;)
	{
		// Display choices
		for(size_t x = 0 ; x < MAX_ITEM ; ++x)
		{
			std::cout << (x + 1) << ". " << szChoices[x] << std::endl;
		}
 
		// Get choice
		std::cout << std::endl << "Enter '0' to quit" << std::endl;
		std::cout << std::endl << "Make your choice: ";
		size_t i = 0;
		std::cin >> i;
 
		// Quit?
		if(0 == i) { break; }
		// Invalid?
		if(i > MAX_ITEM) { std::cout << std::endl << "Invalid" << std::endl << std::endl; }
		// Display
		else { std::cout << std::endl << szChoices[i - 1] << std::endl << std::endl; }
	}
}
                                              

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