I want to know about the symbol % that is written while setting the classpath or while setting the path for the jdk in command prompt in windows.
E.X.
set classpath=%classpath% ;.;
or
set path=%path% ;.;C:\Program Files\Java\jdk1.7.0_01
I want to know about %path% and %classpath%
What do they mean and what is the special % symbol about?
The % notation is used to access environment variables in windows. E.g. in the line
set classpath=%classpath%;.
the part %classpath% is replaced with the current content of this variable and then appended by ;. and then rewritten to the same variable.
On command line promt you can write e.g.
echo %classpath%
which will show you the content directly (as with set classpath).
set classpath without the =newvalue to see the current value, and you can use the command set on its own to see the current value of all environment variables.
$CLASSPATH instead of %CLASSPATH%.Those are environment variables. And environment variables are what you're setting. Basically, they're saying "Take the old value of this environment variable and append the following literal text to it". The % just clues in the command interpreter to do the variable substitution vs treating "path" or "classpath" as literal text.
(Similar but different notation is used in shell interpreters on Unix/Linux.)
%classpath% is the current value of the classpath so
set classpath=%classpath% ;.;
adds the current directory onto the end of whatever the current value of the classpath is.
Likewise, set path=%path% ;.;C:\Program Files\Java\jdk1.7.0_01 adds the current directory and the JDK directory onto the end of the current path.
Note: this is not anything specific to path and classpath. %variablename% is the syntax for the value of the environment variable variablename.
