InStream.READ Function

项目
06/05/2016

Reads a specified number of bytes from an InStream object. Data is read in binary format.

Syntax

  
[Read := ] InStream.Read(Variable[, Length])

Parameters

Variable
Type: Text

Describes the variable that will receive the data that is read.

Length
Type: Integer

Describes the number of characters to be read. If you do not specify Length, the size of the variable is used. In the case of data types other than string, code, and binary, if you specify a length that differs from the size of the variable, you receive an error message.

Property Value/Return Value

Type: Integer

The return value is the number of characters that were read.

Remarks

If the optional return value (READ) is not present and the data being read is less than the length requested to be read, then you receive an error message.

If the return value is present, then you must verify the validity of the data that has been read.

Example

The following example shows how to use the Instream.READ function to read data in binary format. The FIND function finds the first record from the Company Information table. The CALCFIELDS function retrieves the Picture field, which is a BLOB field. The CREATEINSTREAM function uses the recBinaries variable to create an InStream object that is named varInstream. The varInstream.READ function then reads three characters from the varInstream variable and stores the binary data in the varChars variable. The number of characters that is read is stored in the numChars variable. The binary data and the number of characters that is read are displayed in a message box. This example requires that you create the following variables and text constants in the C/AL Globals window.

Variable name	DataType	Subtype	Length
recBinaries	Record	Company Information	Not applicable
Picture	Binary	Not applicable	100
varInstream	InStream	Not applicable	Not applicable
varChars	Text	Not applicable	50
numChars	Integer	Not applicable	Not applicable

Text constant name	ENU value
Text000	Number of characters read: %1. Characters read: %2.

recBinaries.FIND('-');  
recBinaries.CALCFIELDS(recBinaries.Picture);  
recBinaries.Picture.CREATEINSTREAM(varInstream);  
numChars := varInstream.READ(varChars,3);  
MESSAGE(Text000, numChars, varChars);

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