numeric value restriction c++

[parth27987]

I'm obviously a noob @ c++.
Have a question.
is there any way i can restrict user to input only numeric value and make a loop if user enters non-numeric value.

for example for conversion from kilo to pound if user enters some garbage like "afshdgafg" in cin. is there any way i can make user pay for it and make it a loop?

Thanks in advance.

[L7Sqr]

You can not charge a user money. You can, however, ensure that what they input matches what you require. Read this thread for a decent set of examples.

[Cross213]

You could put an if statement after the the user inputs data and if there input does equal what you want then allow them to keep entering until it does.

[parth27987]

well the program converts temperature from one unit to another. how can i restrict them to just enter numerical values and not any characters? i know the buffer system in c++ just sucks but there should be some way don't u think so?

[mike_2000_17]

It is quite easy to check the validity with C++'s formatted input mechanism, which will fail if the input is not of the required format.

Personally, I don't like to fiddle around with the std::cin too much, so I would recommend the intermediate use of std::stringstream.

Something like this would do:

#include <iostream>
#include <sstream>
#include <string>
using namespace std;

int main() {

  int value = 0;
  while(true) {
    cout << "Please enter an integer number: ";
    string tmp;
    getline(cin, tmp);
    if( stringstream(tmp) >> value )
      break;
  };
  return 0;
};

[parth27987]

that helps a lot! thanks.