&cat(4)

NAME

&cat, &lef, &rig, &mid, &len, &slo, &trb - String macro operators

SYNOPSIS

&cat str1 str2
&lef str len
&right str index
&mid str index len

&len str

&slower str
&supper str

&trboth str
&trleft str
&trright str

DESCRIPTION

The string operators operate on character strings (% or $ variables), performing general string manipulation, returning a string result.

The operators may all be abbreviated to their three letter abbreviation (i.e. &right may be expressed as &rig). In all cases the first argument is completely evaluated before the second argument.

&cat str1 str2


Concatenate two string str1 with str2 to form a new string. i.e. str1str2

&lef str len


Return len leftmost characters from str. If str length is shorter than len then the string itself is returned. A len of zero returns the empty string.

&rig str index


Returns the rightmost characters of string str from index index. This function causes some confusion, consider &lef and &rig to be the string equivalents of their integer counterparts &div and &mod; &rig returns the remainder of the equivalent &lef function. Invocation with index set to zero returns str.

&mid index len


Extracts a sub-string from string str, starting at position index of length len.

&len str


Returns the integer length of the string (number of characters).

&slower str


Returns the given string with all upper case characters converted to lower case.

&supper str


Returns the given string with all lower case characters converted to upper case.

&trboth str


Returns the given string trimmed of white spaces (i.e. ' ', '\t', '\r', '\n', '\Cl' and '\Ck') from both sides of the string.

&trleft str


Returns the given string trimmed of white spaces from the left side of the string only.

&trright str


Returns the given string trimmed of white spaces from the right side, or end, of the string only.

Evaluation of the strings is left to right, the leftmost argument is fully evaluated before the next argument. The operator ordering is prefix notation (see &add(4) for an example of prefix ordering).

EXAMPLE

Concatenate two strings abc and def together:-

set-variable %result &cat "abc" "def" 

To concatenate three strings abc, def ghi together:

set-variable %result &cat "abc" &cat "def" "ghi" 

or, a slightly different ordering:

set-variable %result &cat &cat "abc" "def" "ghi" 

Retrieve the leftmost character of a string variable, modify the variable to contain the remainder.

set-variable %foo "abcdef" 
set-variable %c   &lef %foo 1 
set-variable %foo &rig %foo 1 

Where %c = "a"; %foo = "bcdef" following evaluation.

To retrieve the characters cde into variable %result from the string "abcdef" use:

set-variable %result &mid "abcdef" 2 3 

To retrieve the rightmost character from the string:

set-variable %foo "abcdef" 
set-variable %result &rig %foo &sub &len %foo 1 

or the same result could be achieved using &mid:

set-variable %result &mid %foo &sub &len %foo 1 1 

To get an input string from the user which is free of spaces at the start and end:

set-variable %result &trb @ml "Enter string" 

NOTES

The original MicroEMACS "&rig str n" function returns the last n characters from the string str this differs from the definition of &rig in this implementation. As most string decomposition is performed left to right, and to make &lef and &rig complement each other, the indexing of the function has been modified.

SEE ALSO

Variable Functions, &sin(4), &sequal(4), &lget(4), &sprintf(4).

(c) Copyright JASSPA 1999
Last Modified: 1999/02/02
Generated On: 1999/12/01