How can I continue my question until the user enter the valid input?

[selflearner]

Hello, I am writing a code in c++ and I need to ask the user to enter the number between 0-4

0= quit
1-4=do something

so at first I use do and while
for example
do
{
}
while (choice!=0);

so it goes back if the user enter any integer but0-4. However when the user enter a character. it won't work and it will quit right away.

Please help. if you wanna see my code please comment below.

[SamuelAdams]

That's because your using INT for choice, try using char or string.

[48T7M4Gy]

http://www.cplusplus.com/forum/general/180615/

[selflearner]

Hello, @SamuelAdams (841)

but my code is like this and it says switch quantity is not an integer

int main(){

     
       do
    {  string choice;
        choice = selected_option();
    switch(choice)
case0:
{ //this is quit}
case1:
{// do something}
case2:
{...}
case3:
{}
case4:
{}
}
while ( choice!=0);
}
return 0;

}

[48T7M4Gy]

Maybe this is something you could build on:

#include <iostream>

using namespace std;

int main()
{
	int number = 0;
	char choice = '\0';

	while (cin >> choice)
	{
		number = choice - '0';
		cout << number << endl;
	}
      
       return 0;
}

[selflearner]

Hello @kemort
what is '\0' for?

thank you.

[48T7M4Gy]

I like the idea (habit) which is conventional good practice of initialising all variables with a value so I made it zero. That way if it never gets changed you don't get rubbish values creeping in.

The other good practice is not to use using namespace std; but I was lazy this time. Old habits die hard.

[selflearner]

is it like constant ?

[48T7M4Gy]

Sorry, what do you mean by 'constant' or do you mean 'const'?

[selflearner]

yes

[48T7M4Gy]

'const' means essentially 'read-only' to protect against/avoid the item being accidentally changes. Check out the full details when u have time.