LEN
The LEN function returns the number of bytes used by a variable value and the number of characters in a STRING.
Syntax
- length% = LEN(literalTextOrVariable)
- Literal or variable STRING values return the number of string bytes which is the same as the number of string characters.
- A numerical variable will return the number of bytes used by a numerical variable type.
- _BYTE variable types return 1 byte.
- INTEGER variable types return 2 bytes.
- SINGLE and LONG integer variable types return 4 bytes.
- DOUBLE and _INTEGER64 variable types return 8 bytes.
- _FLOAT variable types return 32 bytes.
- _OFFSET and _MEM variable types return varying byte sizes.
- Note: _BIT variable types and bit multiples cannot be measured in bytes.
- LEN cannot return lengths of literal numerical values and will create a "variable required" status error in the IDE.
- LEN = can be used with a user defined TYPE variable to determine the number of bytes used in RANDOM file records:
-
- If a LEN = statement is not used, RANDOM default record length is 128 or sequencial is 512 up to a maximum of 32767 bytes.
- BINARY OPEN statements will ignore LEN = statements. The byte size of a read or write is determined by the variable type.
Examples
Example 1: With a string variable the byte size is the same as the number of characters.
LastName$ = "Williams" PRINT LEN(LastName$); "bytes"
8 bytes
Example 2: Testing INPUT for numerical STRING entries from a user.
INPUT "number: ", num$ value$ = LTRIM$(STR$(VAL(num$))) L = LEN(value$) PRINT LEN(num$), L
- Note: &H, &O, D and E will also be accepted as numerical type data in a VAL conversion, but will add to the entry length.
Example 3: With numerical value types you MUST use a variable to find the inherent byte length when using LEN.
DIM I AS INTEGER PRINT "INTEGER ="; LEN(I); "bytes" DIM L AS LONG PRINT "LONG ="; LEN(L); "bytes" DIM I64 AS _INTEGER64 PRINT "_INTEGER64 ="; LEN(I64); "bytes" DIM S AS SINGLE PRINT "SINGLE ="; LEN(S); "bytes" DIM D AS DOUBLE PRINT "DOUBLE ="; LEN(D); "bytes" DIM F AS _FLOAT PRINT "_FLOAT ="; LEN(F); "bytes"
INTEGER = 2 bytes LONG = 4 bytes _INTEGER64 = 8 bytes SINGLE = 4 bytes DOUBLE = 8 bytes _FLOAT = 32 bytes
Example 4: Opening a RANDOM file using LEN to calculate and LEN = to designate the file record size.
TYPE variabletype x AS INTEGER' '2 bytes y AS STRING * 10' '10 bytes z AS LONG' '4 bytes END TYPE' '16 bytes total DIM record AS variabletype DIM newrec AS variabletype file$ = "testrand.inf" '<<<< filename may overwrite existing file number% = 1 '<<<<<<<<<< record number to write cannot be zero RecordLEN% = LEN(record) PRINT RecordLEN%; "bytes" record.x = 255 record.y = "Hello world!" record.z = 65535 PRINT record.x, record.y, record.z OPEN file$ FOR RANDOM AS #1 LEN = RecordLEN% PUT #1, number% , record 'change record position number to add records CLOSE #1 OPEN file$ FOR RANDOM AS #2 LEN = RecordLEN% NumRecords% = LOF(2) \ RecordLEN% PRINT NumRecords%; "records" GET #2, NumRecords% , newrec 'GET last record available CLOSE #2 PRINT newrec.x, newrec.y, newrec.z END
16 bytes 255 Hello worl 65535 1 records 255 Hello worl 65535
- Explanation: The byte size of the record TYPE determines the LOF byte size of the file and can determine the number of records.
- To read the last record GET the number of records. To add a record, use the number of records + 1 to PUT new record data.
See also
