Commodore PC 20 - Page 251

. [
[-
[~I
C:
c
If
Purpose:
Performs a command based on the result of a condition .
Syntax:
if [NOT) errorlevel number command
or
if [NOT) string! = = sfring2 command
or
if [NOT) exist filename command
Comments:
The if statement allows conditional execution of commands.
When
the condition is true, MS-DOS executes the command, other-
wise it ignores
the command.
The conditions are described as follows:
errorlevel number
True if, and only if, the previous program executed by
command.com had an exit code of number or higher. (When a
program finishes, it
returns an exit code via MS-DOS.) You can use
this condition
to perform other tasks that are based on the previ-
ous program's exit code.
string! = = string2
True if, and only if, string! and string2 are identical after parame-
ter substitution. Strings may not contain separators, such as com-
mas, semicolons, equal signs,
or spaces.
exist filename
True if, and only if, filename exists_
If you specify
the NOT parameter, MS-DOS executes the command
when the condition is false.
Example:
The following example prints the message "can't find datafile"
if the file product.dat does not exist on the disk:
if not exist product.dat echo can't find datafile
Batch Processing 113
If
Displaying a
conditional message