Test integerness
Given a real numeric value, test whether or not it is an integer.
Test integerness is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.
J
<lang J>(= <.) 3.14 7</lang>
- Output:
0 1
Perl 6
<lang perl6>say pi.narrow ~~ Int; say 1e5.narrow ~~ Int;</lang>
- Output:
False True
Python
<lang python>>>> def isint(f):
return int(f) == f
>>> isint(3.14) False >>> isint(3.0) True >>> </lang>
Rexx
<lang rexx>/* REXX ---------------------------------------------------------------
- 20.06.2014 Walter Pachl
- --------------------------------------------------------------------*/
Call test_integer 3.14 Call test_integer 33 Call test_integer 999999999 Call test_integer 99999999999 Call test_integer 1e272 Call test_integer 'AA' Call test_integer '0' Call test_integer '-3' Exit test_integer: Parse Arg x Numeric Digits 1000 Select
When datatype(x)<>'NUM' Then Say x 'is not an integer (not even a number)' When x=0 Then Say x 'is zero and thus not an integer' When x<0 Then Say x 'is negative and thus not an integer' Otherwise Do If datatype(x,'W') Then Say x 'is an integer' Else Say x 'isnt an integer' End End
Return </lang> output
3.14 isn't an integer 33 is an integer 999999999 is an integer 99999999999 is an integer 1E272 is an integer AA is not an integer (not even a number) 0 is zero and thus not an integer -3 is negative and thus not an integer /pre> =={{header|Tcl}}== The simplest method of doing this is testing whether the value is equal to the value after casting it to a integral value. <lang tcl>proc isNumberIntegral {x} { expr {$x == entier($x)} } foreach x {3.14 7 1000000000000000000000} { puts [format "%s: %s" $x [expr {[isNumberIntegral $x] ? "yes" : "no"}]] }</lang> {{out}} <pre> 3.14: no 7: yes 1000000000000000000000: yes