MDRVMDNMSTRINGS


Douglas Boling September 10, 1991 (Utilities)

To enable batch files to manipulate strings, request and interpret
user input, process files, return system information, and perform simple math
by adding functions to the batch file language. Stores information in either
the local or the master environment.

Format: STRINGS [/?][/M][/Pc][environment var =] FUNCTION
[str1][, str2][, str3]

Remarks: Entered with the /? switch, STRINGS presents a multi-screen help
list of its FUNCTION calls and their user-supplied parameters (str1, str2,
str3), which is printed overside. By default, STRINGS uses the local
environment (as do batch files) to store user-named environment variables; the
/M switch places these in the master environment, where they can be accessed
by multiple DOS sessions under Windows. The /M switch is also useful for
preserving variable assignments made when shelled out from an application, for
the default local environment is lost when you exit from DOS back into the
running program.

The parse character, used to separate parameter strings, can be
changed from the default comma to any unused character c, by specifying the
/Pc switch. Leading spaces before a parameter string are normally ignored;
they can be preserved by doubling the parse character (which is not printed)
immediately before the beginning of the parameter.

To illustrate the syntax, using one of the functions listed overside,
if executed from within a .BAT file, the command

STRINGS /M XYZ = MID This is a sample string, 11, 6

would store the word sample (which starts with the 11th character in
the parameter string and itself occupies 6 characters) under the variable name
XYZ in the master environment. STRINGS could later be used to retrieve this
value by using the MASTERENV function and specifying XYZ as its parameter.

A null string is returned if 0 characters are specified when using the
LEFT or RIGHT functions, or if a starting character larger than the string
length is requested when using the MID function. Assigning a null string to a
variable erases that variable name from the environment.

ERRORLEVEL 1 codes are returned by attempting to READ line 0 or a line
number greater than contained in the specified file, and by attempting to
WRITE (append a line to) a read-only file. The SUB (subtract) function also
returns an ERRORLEVEL 1 code when the result is a negative number; this can be
used by a batch file to implement a compare function.

The table below lists the functions supported by STRINGS, together
with the parameters to be supplied. A fuller account of each of these is
printed in the original article.

Function Description Parameters to Supply

LEFT Returns left n chars String, No. chars
RIGHT Returns right n chars String, No. chars
MID Returns middle n chars String, Start char, Len.
LENGTH Returns string length String
FIND Finds position of findstring String, findstring
FINDC Case sensitive FIND String, findstring
LOWER Returns string all lowercase String
UPPER Returns string all uppercase String
CHAR Returns ASCII no. of char Character
VAL Returns ASCII char of no. Number
READ Returns a line from a file Filename, line number
WRITE Writes string to end of file Filename, String
FILESIZE Returns file size Filename
LINESIZE Returns no. of lines Filename
FILENAME Returns filename Filespec
FILEEXT Returns file extension Filespec
TRUENAME Returns qualified filename Filename
ASK Returns user response [Prompt string]
ADD Returns the sum of two nos. Number, Number
SUB Returns difference of two nos.Number, Number
MUL Returns product of two nos. Number, Number
DIV Returns quotient of two nos. Number, Number
VER Returns the DOS version no.
ENVFREE Returns the bytes free in the environment
ENVSIZE Returns the size of the environment
MASTERVAR Returns a variable from the Master env.