The 'Value attribute is defined for any scalar type. This attribute is a function that parses the string and returns the corresponding type value, if it exists. Leading and trailing spaces are trimmed.
If the string does not correspond to any value of the type, then the Constraint_Error exception is raised.
There are corresponding attributes for Wide_String and Wide_Wide_String.
Don't confuse this attribute with the Ada Programming/Attributes/'Val attribute.