11.2 Character array stripping, padding, and truncation

CharArrays are designed to store fixed length strings of visible ASCII text. You may have noticed that although a CharArray stores fixed length strings, it displays variable length strings. This is a result of the stripping and padding policies of the CharArray class.

When an element of a CharArray is fetched trailing whitespace is stripped off. The sole exception to this rule is that a single whitespace is never stripped down to the empty string. numarray.strings defines whitespace as an ASCII space, formfeed, newline, carriage return, tab, or vertical tab.

When a string is assigned to a CharArray, the string is considered terminated by the first of any NULL characters it contains and is padded with spaces to the full length of the CharArray itemsize. Thus, the memory image of a CharArray element does not include anything at or after the first NULL in an assigned string; instead, there are spaces, and no terminating NULL character at all.

When a string which is longer than the itemsize() is assigned to a CharArray, it is silently truncated.

The RawCharArray baseclass of CharArray implements transparent strip() and pad() methods, enabling the storage and retrieval of arbitrary ASCII values within array elements. For RawCharArray, all array elements are identical in percieved length. Alternate stripping and padding policies can be implemented by subclassing CharArray or RawCharArray.

Send comments to the NumArray community.