CODEWITHSUNDEEP
c++
user655321
user655321

Reputation: 143

Trying to validate user input to make sure it is one of two characters

I am starting to learn the C++ syntax and I am attempting to validate user input in a program I am writing. Here is what i try to do:

string genderC;
cout << "Enter 'm' for male and 'f' for female:" << endl;
cin >> genderC;
while( !(cin >> genderC) || genderC != 'f'|| genderC != 'm') {
    cout << "Bad input\nEnter 'm' for male and 'f' for female:" << endl;
    cin.clear();
}
//...

it gives me the following error:

invalid operands to binary expression ('string' (aka 'basic_string<char, char_traits<char>,     allocator<char> >') and 'int')

Any help would be appreciated. Thank you.

Upvotes: 1

Views: 303

Answers (3)

Fr&#233;d&#233;ric Marchal
Fr&#233;d&#233;ric Marchal

Reputation: 1004

The genderC variable is of type "string" and you are comparing it with 'f' and 'm' which are of type "char" due to the single quotes.

Your problem should be fixed if you rewrite your while loop like this:

while( !(cin >> genderC) || genderC != "f" || genderC != "m") {

Due to the double quotes, "f" and "m" are of type "char*" which can be compared with "string".

Note that the compiler is referring to those two literal "char" type as "int" because char is, in fact, an 8-bit integer.

Upvotes: 0

Simon
Simon

Reputation: 6363

You're comparing a string to a char. char is an integer type which is why you get the error message saying that you can't compare a string to an int.

'f' and 'm' are of type char while genderC has type std::string.

So you have two options:

  1. Take input of type char
  2. Compare genderC to "f" and "m" (which are strings) instead

Upvotes: 1

Christos
Christos

Reputation: 53958

You have to change this

genderC != 'f'|| genderC != 'm'

to this:

genderC != "f" || genderC != "m"

The genderC is a string and a string is a sequence of characters between two ". If genderC was a char, you wouldn't had any problem.

Upvotes: 1

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