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c++mathdigits

C++: finding a specific digit in a number

Someone please guide me how to check whether a specific digit exists in an integer or not. for the sake of code optimization I am trying to avoid the use of strings or any kind of loops to iterate over all the digits of the integer.

If I need to find out whether 4 exists the in an integer or not, input and the output samples are given below:

Sample Input:

154

Sample Output:

true

Desired Code:

bool ifExists(int digit, int number)
{
    if()
    {
        return true;
    }
    else
    {
        return false;
    }
}

Possible Logic:

I believe there must be a mathematical approach which will do the job in the if condition, however I am unable to find such method in cmath library.

Solution

  • Convert integer to string, do a string search for digit.

    The "mathematical" method would have to do the same, compute the digit sequence by division/remainder by 10 and compare with the given digit.