New in version 6.3.0: See the new features.
Writing data to a sequential file, socket or pipe¶
fwrite |
Writing data to a sequential file, socket or pipe |
SYNTAX
Writes binary data from the listed records and fields to a sequential file, socket or pipe which is open on the specified file_handle. The total number of bytes written will equal the sum of sizes of the expression’s supplied.
file_handle |
It can be the handle returned by the fopen command (it returns a negative number to differentitate the #channel case) or an integer in the range 1-64 specifying the number of the channel on which the sequential file, socket or pipe (opened by the open # command) is open. It may be a constant, field name or expression. |
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expression |
It can be a Sculptor keyed file field, !record field or a temporary field declared in the program. The fields may be of any type. Or a record_id that refers to a !record or a ![o]file declared in the program. Including record arrays and nested records. Or just an expression (funcion calls, operations, constants…) The data is written as binary data directly from the supplied expression. The size of the data written to the file is equal to the binary size of the data written. |
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[err = label] |
Errors return the trappable condition err, which may be trapped by the err = clause or by the general traps = clause. The error number is stored in the system variable sys.Error , and control passes to the line indicated by label. The error numbers are defined by manifest constants in the file errors.h, which is located in the Sculptor include directory. This file may be included in a program by means of an !include declaration. The possible errors are:
If an error occurs and is not trapped, an error message is displayed and control passes to the active menu, if any. If no menu is active the program exits. |
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[to = timeout[:label]] |
Defines the timeout value and if the label is defined then control passes to the line indicated by label, in case the timeout is reached. If this condition is not trapped, the error timeout exceeded is displayed and control passes to the active menu, if any. If no menu is active the program exits. |
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[traps = label] |
General purpose trap clause that traps any condition not explicitly trapped, passing control to the line indicated by label. It has the lowest priority, and is only invoked if a trappable condition has not been more explicitly trapped. |
NOTES
If the handle/channel is already closed the command is ignored.
EXAMPLE
This example shows a field and record write:
!temp fHandle,,i2
!temp magic,,i4
!record dataRec {
Name,,a32,,v
Surname,,a32,,v
Age,,u2
}
fopen fHandle "seqfile" "w"
magic = MAGIC_NUMBER
dataRec.Name = "name"
dataRec.Surname = "surname"
dataRec.Age = 30
/* Write the magic number and the !record */
fwrite fHandle magic, dataRec
fclose fHandle
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