How to check a number is decimal number or whole number in c/c++?

general
1

Hi all I need a solution that how to check a number whether it is a decimal or whole number. I had checked this in google but the solutions are in Javascript, Php,Html. I need the solution in c/c++ .

2

Give an example for more clear -

3

1400 is a whole number
189.999 is a decimal number likewise

1 Like
4 
void check(long double n){
   if(ceil(n) == floor(n))
        print("Whole")
   else
        print("decimal")
}
2 Likes
5

Any doubt ? @anon71261517

6

The above code snippet fails here.

1 Like
7

Best would be, take the input as string. Now check if “.” is present in the string, its a decimal number else its whole number

         #include<bits/stdc++.h>
         using namespace std;
         int main(){
                string s;
                cin>>s;
                bool flag=false;
                for(int i=0;s[i];i++){
                      if(s[i]=='.'){
                             flag=true; 
                             break;
                      }
                }
                if(flag){
                      cout<<"Decimal number";
                }
                else{
                     count<<"Whole number";
                }
         }
8

mathematically 2.0 is decimal in cp is it considered as whole ? @mohittkkumar

9

see the number i have used has a ‘1’ at 6th place after decimal. see the main function :slight_smile:

10

Yeah i saw and but i m asking simple in CP 2.0 will be treated as decimal or whole ? @anon71261517

11

Decimal … but the question he asked was whether the decimal has fraction part equal to 0 or not.

12

Then best method is input a number as string -
If ‘.’ in string then it will be decimal otherwise whole.

If user consider 2.0 as whole then after ‘.’ there must be only zeroes no other digit.

13

Take input as a string
if(any element after ‘.’ is greater than one )
decimal
if(any no number after ‘.’ (or) all elements after ‘.’ are zeros)
whole

14

This Might work:

  int main() 
  {
   #define int long long int 
   long double n;
   cin>>n;
   if((long double)n==(int)n)cout<<"Whole"<<endl;
   else cout<<"Decimal"<<endl;
  }
15

How about this ?

void tell(double n) {
    if(n == (int)n)
        cout << "whole";
    else
        cout << "decimal";
}
16

That will suffice…

@anon71261517 don’t pass the decimal to any function, just check with these two lines.

17

Yes,this code is working on the test case you mentioned before.

18

You can do this

    if(n%1==0){
          cout << "Whole" <<endl;
       }else{
          cout << "Decimal" << endl; 
        }
19

If the problem is to find if it’s a decimal number, then the best method is to take the input as a string.

If at some point in your implementation you want check if you have an integer or a floating point value, then I’m sorry but you have to try a different logic. Checking if n == (int) n or if floor(n) == ceil(n) will fail when the fractional part is so small, and it’s truncated and stored in the double as a pseudo integer.

20

great soln