How can I write a switch statement with strings in C++? [duplicate] - c++

Question

This question already has answers here:
Why can't the switch statement be applied to strings?
(22 answers)
Closed 3 years ago.
I'm working on a small project on Dev-C++. I'm trying to make a bot to ask you some questions, but I can't use the switch statetments with the strings. Every time I try to do so it shows error! I also tried to change the srings to normal int variables but when I the code runs all at once after answering the first question! Does anyone knows how to fix any of these situations?
Here is my code:
// #include "stdafx";
#include <iostream>
#include <string>
#include <stdio.h>
#include <string.h>
using namespace std;
int main()
{
string comida;
string nome;
string idade;
string pais;
cout << "Ola, o meu nome e Aleksandar. Qual e o teu nome?" << endl; //Ask for nome
cin >> nome; //Recieve variable nome
cout << "Es de que pais, " << nome << "?" << endl; //Ask for pais
cin >> pais; //Receive pais
cout << pais << " e um pais bonito. " << "Eu sou de Portugal!" << endl;
cout << "Quantos anos tens " << nome << "?" << endl; //Ask for idade
cin >> idade; //Receive variable idade
switch (idade) {
case 21:
cout << "O meu irmao tambem tem 21 anos!" << endl;
break;
}
cout << "Eu tenho 28" << endl;
cout << "Qual e a tua comida preferida?" << endl; //Ask for comida
cin >> comida; //Receive variable comida
cout << "Tambem gosto muito de " << comida << ". Mas gosto mesmo e de Vatruchka!" << endl;
cout << "Xau " << nome << "!" << endl;
}

Answer 1

If the string contains a number, switch(std::stoi(idade)) will work. But that doesn't work if idade contains something else.

Answer 2

A switch will not compile when non-intergal (i.e. string, float, bool, vector, etc...) data-types are assigned to the switch's case: statements. Furthermore, its necessary that the values assigned to the case: statements are const.
In other words:
Switches must use "constant integral data-types" (i.e. 'enum', 'int', 'char', etc...), and cannot implament strings as conditional statements, however; that is not the same as saying that strings cannot be used in a conditional statement, they very much can be & often are — see the example below:
std::string s;
std::cin >> s;
if (s == "Yes")
{
std::cout << "You said yes!" << std::endl;
}
else if (s == "No")
{
std::cout << "You said no?" << std::endl;
}
else
{
std::cout << "You said something I don't understand" << std::endl;
}
So to finish this answer, you can see that you can achieve the same thing you could with a switch statement using if/else blocks. It may, or it may not, be ideal for your situation, but this is how C++, and switch statements work, so your stuck with it — like it, or not...

Answer 3

You can't use strings — switch only works for integral case types (i.e. integers and enums).
You could use something like this, instead:
if (idade == "21") { cout << "...\n"; }
else if (idade == "something else") { cout << "...\n"; }
You describe that the code runs all at once when you change to using integers. It's possible you're forgetting to include break in each case clause.

Answer 4

If you have a set of different strings that you are expecting then you can set up an enum and a map (I use the word map loosely here - I don't mean the actual map in C++, although I know it is possible to do something similar with it)
Use this to turn the input into an enum and then you can run a switch on the enum
E.g.
enum class ANSWER
{
ANSWER_1,
ANSWER_2
};
class AnswerMap \\set up this class like a singleton
{
std::vector<std::pair<std::string, ANSWER>> _answer_map = {
std::make_pair("Answer 1 string", ANSWER::ANSWER_1),
std::make_pair("Answer 2 string", ANSWER::ANSWER_2)
}
std::string String(ANSWER answer); \\have this function loop through this->_answer_map until finding the pair with the second item as the given enum and return the corresponding string
ANSWER Enum(std::string answer); \\have this function do the same as this->String but find the pair where the string matches and then return the corresponding enum
}