How to determine whether a string represents an integer?

Question

I need to determine if a string contains just an integer. The built-in function isinteger is not working.

To avoid loops I'd like to apply this task on cell arrays of strings. For example:

Q = { 'qf5' ; '4' ; 'true' ; 'false' ; '4.00' ; '4E0' ; '4e0' ; '657' }; 

desired result:

integers = 0  1  0  0  0  0  0  1

For a single string I figured out an ugly workaround, but I can't imagine that this is the only possible way, and also it requires a loop to use it on cell arrays:

myString = '4';
integer = uint64( str2double( myString ) );
newString = int2str( integer );
isStringInteger = strcmp(newString,myString);

Which essential function am I missing?

Answer 1

You can do it with regexp; and to avoid the loop you use cellfun:

~cellfun('isempty', regexp(Q, '^-?\d+$'))

This considers an "integer" as a string of digits, possibly with one minus sign at the beginning.

Note that cellfun with the builtin function 'isempty' is very fast.