CODEWITHSUNDEEP
c++
Cristian C.
Cristian C.

Reputation: 828

How to make a function not ask for additional input based on initial input

I need to make a program that reads in the users weight/height.

The user needs to be able to input a number and then a unit of measurement right after. This can be in feet/inches, meters, or cm.

I've gotten all that to work, but the user should also be able to write something such as 5' and have the inches be optional.

Here's the problem I'm having:

I have two variables I'm using for user input, one double (height), and one string (unitHeight). that works fine for m and cm, but for feet/inches I needed to add two more since the user needs to input two strings and two numbers (I kept it as doubles for simplicity's sake).

so I used an if statement:

if (unitHeight == "'"){
    cin >> height2;
    cin >> unitHeight2;
}

The problem is that I need to make it so that when the user inputs x' (x being whatever number), the program doesn't ask for any further input.

Upvotes: 1

Views: 2165

Answers (3)

R Sahu
R Sahu

Reputation: 206567

Read the stdin one line at a time. Process each line. If a line contains a second number (for height) and second string (for the unit), then you have the feet+inches specification. Otherwise, you just have one number and one unit.

const int maxLength = 200;
while (true)
{
   char line[maxLength+1];
   std::cin.getline(line, maxLength);
   if ( !cin.good() )
   {
      break;
   }

   std::istringstream str(line);
   double height1;
   std::string unit1;
   double height2;
   std::string unit2;
   bool secondHeightFound = false;
   str >> height1 >> unit1 >> height2;
   if ( str.good() )
   {
      str >> unit2;
      secondHeightFound = true;
   } 
}

Upvotes: 0

Tony Delroy
Tony Delroy

Reputation: 106076

What to do depends a bit on what other input (if any) might come after the height, and how you want to handle errors, but to get you started:

int height2 = 0;
if (unitHeight == "'" && cin >> height2)
{
    if (!(cin >> unitHeight2))
    {
        std::cerr << "hey, " << height2 << " what?  give me units baby!\n";
        exit(EXIT_FAILURE);
    }
    // if we get here, then we have height2 and unitHeight2 to work with...
    ...

}
else if (cin.eof())
{
    // might have hit EOF without inches, that could be legal - depends on your program
    ...
}
else
{
    // saw some non-numeric input when expecting height2 - is that ok?
    ...
}

Since you posted, you've added a comment saying that you specifically want this input on a single line, after which the user can be expected to press enter. To handle that, surround the above code with std::string line; if (getline(std::cin, line)) { std::istringstream iss(line); >>above code goes here<< } else { ...couldn't read a line of input...}.

Separately, you say:

the user needs to be able to input a number and then a unit of measurement right after. this can be in feet/inches, meters, or cm. ive gotten all that to work

...I hope so, but note that it's a bit tricky when supporting e.g. 5'11" and 180cm, as cin >> height1 >> unitHeight1, when unitHeight1 is a std::string, will read "'11". If you make unitHeight1 a char then it will tend to read only the "c" from "cm", so neither type works for both notations. You'd best read a char then use it to decide whether to read another....

Upvotes: 2

Fernando de Oliveira
Fernando de Oliveira

Reputation: 101

You can do something like that:

string height;
cin >> height;

for(int i = 0; i < height.size(); i++) {
    if(height[i] == "'"[0]) {
        cout << "It's ok!" << endl;
        break;
    }
}

Upvotes: 0

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