Using the Brackets Operator for Extraction
Description
Extracts a substring from a string. Does not affect the original string.
Syntax
variable[start, length, <byteOffsetFlag>]
Remarks
The brackets operator has the following parameters when used for extraction.
| Parameter | Description |
|---|---|
| variable | Contains the string on which the extraction operation is performed. |
| start | A positive or negative integer. If start is a positive number, the operation will begin at the character in that position, counting from the first character or space at the beginning of the string. If start is a negative number, the operation will begin at the character in that position, counting from the last character or space at the end of the string. If start is 0 (zero) or 1, the operation will begin with the first character or space at the beginning of the string. |
| length | Number of characters to extract, beginning from start. Each space and character within the string is counted as a character position. Also, note that the value specified for length includes the character position specified by start. If length begins with 'F', then the extraction process begins at start, and continues forward until the character following F is found. The character following F, which acts as a delimiter, is not included in the extraction. If length begins with 'B', the extraction process proceeds backward, until the delimiter is found. Note: If length is a character, and neither "F" nor "B" prefixes the character, an "F" is assumed. |
| byteOffsetflag | Optional. When set to TRUE$, the start parameter is treated as a byte-offset position rather than a character position. Using a byte-offset offers better performance in a UTF8 application when used with the BCol1() and BCol2() operators. |
Remarks
After the extract operator, you can call COL1() and COL2() operators to find the start and end character positions of the operation. The BCol1() and BCol2() operators return the byte-offset starting and ending positions.
Example
* Some simple examples a = "this is a test" b = a[2,3] ; * "his" c = a[-3,3] ; * "est" d = a[4,"t"] ; * "s is a" * Get the first or last word e = a[1,' '] ; * "this" f = a[-1,'B '] ; * "test"
* Using the col2() operator to extract successive elements of a delimited string appID = reposID[1,"*"] typeID = reposID[col2()+1,"*"] classID = reposID[col2()+1,"*"] entID = reposID[col2()+1,@fm]
See Also
Extracting a Substring, COL1(), COL2(), BCol1(), BCol2()
For more details, please refer to this blog post