- BRASS TIMEKEEPER BATCH 2 NUMBERS HOW TO
- BRASS TIMEKEEPER BATCH 2 NUMBERS SOFTWARE
- BRASS TIMEKEEPER BATCH 2 NUMBERS WINDOWS
for /F "tokens=* delims=0" %%I in ("%MyVar%") do set "MyVar=%%I"įOR removes all 0 at beginning of string assigned to MyVar and assigns to loop variable I the remaining string which is assigned next to environment variable MyVar.įOR runs in this case set "MyVar=%%I" even on user entered 0 or 000 with the result of executing set "MyVar=" which undefines environment variable MyVar in this special case. For that reason the leading zero(s) should be removed before further processing variable value. But the number should be interpreted as decimal number even on user input it with one or more 0 at beginning. Windows command processor interprets numbers with a leading 0 as octal numbers. In all other cases including a string starting with after zero or more digits results in execution of goto PromptUser because of input string contains a non-digit character. The command FOR does not execute goto PromptUser if the entire string consists of just digits. Checking for any invalid character can be done for example with: for /F delims^=0123456789^ eol^= %%I in ("%MyVar%") do goto PromptUser So any other character than 0123456789 in user input string is definitely invalid. The user should enter a positive decimal number in range 0 to 20000. The example above with a by mistake entered " instead of 2 results in execution of set "MyVar=" which undefines the environment variable MyVar which is the reason why the IF condition as used before must be used again before further processing of the user input. Therefore the finally executed command line set "MyVar=whatever was entered by the user" is safe on execution.
BRASS TIMEKEEPER BATCH 2 NUMBERS WINDOWS
The Windows command processor removes all doubles quotes already on parsing this line before replacing %MyVar:"=% with the resulting string. For that reason two more lines can be used to prevent wrong processing of user input string caused by ". Remove all " from user input string if this string should never contain a double quote character.Ĭharacter " is definitely invalid in a string which should be a number in range 0 to 20000 (decimal).Enable delayed expansion and reference the environment variable using !MyVar! or "!MyVar!" as now the user input string does not affect anymore the command line executed by cmd.exe after parsing it.See also How does the Windows Command Interpreter (CMD.EXE) parse scripts? On MyVar holding a string with one or more " all %MyVar% or "%MyVar%" environment variable references are problematic because of %MyVar% is replaced by Windows command processor by user input string with one or more " which nearly always results in a syntax error or the batch file does something it was not designed for. So if the user hits 2 and RETURN quickly or without looking on screen as many people do on typing on keyboard, a double quote character instead of 2 was entered by mistake by the user.
BRASS TIMEKEEPER BATCH 2 NUMBERS SOFTWARE
For example pressing on a German keyboard key 2 on non-numeric keyboard with CapsLock currently enabled results in entering ", except German (IBM) is used on which CapsLock is by software only active for the letters. The user could enter a string with one or more " intentionally or by mistake. Note: It is possible to use something different than set "MyVar=" like set "MyVar=1000" to define a default value which can be even output on prompt giving the user the possibility to just hit RETURN or ENTER to use the default value. It is easy to verify in this case with environment variable MyVar explicitly undefined before prompting the user if the user entered a string at all with: if not defined MyVar goto PromptUser If the user hits just key RETURN or ENTER, the environment variable MyVar is not modified at all by command SET.
BRASS TIMEKEEPER BATCH 2 NUMBERS HOW TO
Rem Prompt user for a positive number in range 0 to 20000.Īs I explained by my answer on How to stop Windows command interpreter from quitting batch file execution on an incorrect user input? the user has the freedom to enter really anything including a string which could easily result in breaking batch file execution because of a syntax error or resulting in doing something the batch file is not written for. Rem Undefine environment variable MyVar in case of being already defined by chance. Let us assume the batch file contains: off
0 kommentar(er)
