CHARP - set up a character pointer into a string.
Alternate Entry Name: .CHARP
Usage:
B:
char_pointer = charp( word_address [, byte_offset] );
/* C users just use & operator */
Where:
- word_address
- is the address of a word in memory, generally inside a
string.
- byte_offset
- specifies which byte you wish to point to in the word.
For example, "charp( string, 2 )" will create a
pointer to the byte which is two bytes past the beginning
of "string". Thus if "string" points
to the B string "abcd", the given pointer will
reference the byte where the 'c' is stored. If
"byte_offset" is not specified, the default is
zero, i.e. the starting byte of the word.
- char_pointer
- is a "charp", i.e. the offset of a specific
byte in memory relative to memory location zero.
Description:
CHARP takes a word address and an optional byte offset and
returns a "charp" byte offset. The byte located by the
address plus the offset can then be fetched or replaced using
this "charp" in conjunction with the library functions
STAR and LSTAR.
Bytes before or after the specified byte can be referenced by
incrementing or decrementing the "charp" character
pointer.
See Also:
expl b lib star
expl b lib lstar
Copyright © 1996, Thinkage Ltd.