{{keywords>wiki library source code example reference}}
===== isdigit =====
<code cpp>
    int isdigit(int chr);
</code>

tests if a character a digit

===== cpp Sourcecode Example =====
<code cpp>
#include <iostream> /* including standard library */
#include <string>
#include <cctype>

using namespace std;
int main ( void )
{
  int i;
  string str="Test\n-!&%1";
  for (i=0; i <= 11;i++)
    {
     if ( isdigit(str[i]) != 0 )
      {
       cout << "Character " << i << " is a digit" << endl;
      }
    }
  return 0;
}
</code>

==== output ====
    Character 9 is a digit