1、vba语言基础（VBA language foundation）VBA language foundationSection 1 identifierI. definitionAn identifier is a symbol that identifies variables, constants, processes, functions, classes, and so forth, and uses them to complete references to variables, constants, processes, functions, classes, and so for
2、th.Two. Naming rules1) initial letters, consisting of letters, numbers, and underscores, such as A987b_23Abc2) character length of less than 40, (more than Excel2002 Chinese version, etc., you can use Chinese characters, and the length of up to 254 characters)3) with VB reserved word names, such as
3、public, private, dim, goto, next, with, integer, single etc.Second section operatorDefinition: an operator is a symbol that represents the function of some VB operation.1) assignment operator =2) + (character, mathematical operator pathname optional arguments, string expressions used to specify file
4、 names, and may contain directories or folders, and drives. If no pathname is found, the zero length string (“) is returned; the attributes optional parameter. A constant or numeric expression whose sum is used to specify file attributes. If omitted, a file that matches pathname but does not contain
5、 attributes is returned.2) deleteKill pathname removes files from disk, and the pathname parameter is used to specify a file nameRmDir pathname removes the deleted directory from disk, and the pathname parameter is used to specify a folder3) openOpen, pathname, For, mode, Access, access, lock, As, #
6、filenumber, Len=reclength can be input / output (I/O) to the file.Pathname necessary. String expression. Specifies the file name. The file name may also include directories, folders, and drives.Mode necessary. Keyword specifies the file mode, Append, Binary, Input, Output, or Random. If not specifie
7、d, open the file in Random access mode.Access optional. Keyword describes the operations that an open file can perform, Read, Write, or Read Write operations.Lock optional. Keyword that describes the operations that are restricted to files opened by other processes, such as Shared, Lock, Read, Lock,
8、 Write, and Lock Read Write operations.Filenumber necessary. A valid file number ranging from 1 to 511. Using the FreeFile function, you can get the next available file number. Reclength optional. A number less than or equal to 32767 (bytes). For files that are opened by random access, the value is
9、the length of the record. For sequential files, the value is the number of buffered characters.The document must be opened before any I/O operation is done. The Open statement allocates a buffer for the file to be used by the I/O and determines how the buffer will be used.If the file specified by pa
10、thname does not exist, you can build this file when you open the file in Append, Binary, Output, or Random mode. If the file has been opened by another process and does not allow the specified access type, the Open operation fails and there is an error. If mode is the Binary method, the Len clause i
11、s ignored.It is important to open the same file with different file numbers in the Binary, Input, and Random modes without closing the file first. In Append and Output, if you want to open the same file with different file numbers, you must close the file before opening the file.4) read inInput, #fi
12、lenumber, and varlist read data from the opened sequential file and assign data to variablesGet, #filenumber, recnumber, and Varname read an open disk file into a variable.5) writeWrite, #filenumber, and outputlist write data to the sequential filePrint, #filenumber, and outputlist write the display
13、ed data to the sequential filePut, #filenumber, recnumber, and Varname write the data of a variable to disk files.6) offClose filenumberlist closes the input / output (I/O) file opened by the Open statementNote that if in the future to read file data using Input # statement, will use the Write # sta
14、tement without Print # statements to write data to a file. Because in the use of Write #, the data can ensure the integrity of the domain boundaries of each data domain, so Input can be used to read out the data #. The use of Write # can ensure that any area data to be read correctly. Write and Prin
15、t # statement, when you want to write data to a file, the Write # statement will insert a comma between the project and used to tag string quotes. Write # statement in the last character in the outputlist file will insert a newline character, enter newline (Chr (13) + Chr (10).7) other file function
16、sLOF (filenumber) returns a Long that represents the size of the file opened with the Open statement, which is in bytes.EOF (filenumber) returns a Integer that contains the Boolean value True, indicating the end of the file that has been opened for Random or sequential Input.Loc (filenumber) returns a Long that specifies the current read / write location in the open fileSeek (filenumber) returns a Long that specifies the current read / write location in the file opened by the Open statement
