to set the color of the windows cmd prompt

Basically I  too fall in that 'customizing-freak' category to customize certain features of the OS apart from the specific applications we work on.

One among them is, to have the preferred font, foreground and background colors in the Comman Prompt and with a shortcut to the command prompt on the Quick Launch bar.

Just today when i was searching for a help command for another utility (services.msc), got to know about this favorite-and-regular routine of mine. 

Windows has a command utility named Color with an argument to set the foreground and background colors for the window being opened.

I bet no one can beat the Microsoft's help/documentation. so for  your info, just copy-pasting the information available in the help!

Command : color help

Sets the default console foreground and background colors.

COLOR [attr]

  attr        Specifies color attribute of console output

Color attributes are specified by TWO hex digits -- the first

corresponds to the background; the second the foreground.  Each digit

can be any of the following values:

    0 = Black       8 = Gray

    1 = Blue        9 = Light Blue

    2 = Green       A = Light Green

    3 = Aqua        B = Light Aqua

    4 = Red         C = Light Red

    5 = Purple      D = Light Purple

    6 = Yellow      E = Light Yellow

    7 = White       F = Bright White

If no argument is given, this command restores the color to what it was

when CMD.EXE started.  This value either comes from the current console

window, the /T command line switch or from the DefaultColor registry

value.

The COLOR command sets ERRORLEVEL to 1 if an attempt is made to execute

the COLOR command with a foreground and background color that are the

same.

Example: "COLOR fc" produces light red on bright white.

My preference goes as : "Color 0a" :P

Note: It just sets the colour for the current window being opened! :)

Another Info about the 'DefaultColor' registry value: it is present in the HKEY_USERS/.DEFAULT/Software/Microsoft/CommandProcessor directory in 'regedit' (Registry Editor).

tasklist - cmd in windows similar to ps cmd in linux

The people who have worked in Unix and its flavours, would have definitely come across a command called 'ps' (which stands for 'process status'). As such the 'ps' command gives you the list of processes running and the pid (process id) etc.,

There is a command to achieve the same in Windows OS too. That is 'tasklist'. Just execute in the command prompt. Here it gives the "Image Name", "PID", "Session name", "Session#", "Mem Usage".

Image Name -> the name of the process running
PID -> as you know, the process id (unique id which the OS refers to)
Session name -> it shows 'Console' but have to check what it really means
Session # -> should be a session id and for console it gives '0'.
Mem usage -> the amount of memory each task/process occupies.

Here is the sample screenshot of the same.

It looks like the CUI version of the 'task manager' :)

NOTE: It may not work in all versions of Windows. As such i have tested in Windows XP. I believe it must definitely work in 2000 also. Not sure about the previous versions of 98,95 etc., will check and update later.

Pass by value Vs Pass by Reference

We all would have read the two terms "pass-by-value" and "pass-by-reference" especially when you deal with methods (which are also called as functions).

Let's just have a quick glance at both the terms with a small example.

The definition of these terms goes as follows.

Pass-by-value: A copy of the value is being passed from the calling method to the called method.

What exactly do you mean by copy of the value? In general, we tend to pass the variable for the value to be passed. In such case, whatever the value the variable holds is being copied and passed across. That means, you are taking a xerox of the o riginal value and pass the xeroxed copy to the called method.

What are the effects?
Since you have only passed the xeroxed copy and NOT the original value, whatever changes you do in the called method, the change is not reflected back to the original variable.

A Sample program for pass-by-value:

void changeValue(int a)
{
int b = ++a;
printf("changeValue -> a, b contain: %d,%d",a,b);
}

int changeAndReturn(int a)
{
int b = ++a;
printf("changeAndReturn -> a,b contain : %d,%d",a,b);
return b;
}

int main()
{
int i = 1;
changeValue(i);
j = i;
printf("\ni and j is : %d,%d\n",i,j);
printf("\ncalling changeAndReturn()..");
changeAndReturn(i);
j = i;
printf("\nNow i and j contain: %d,%d",i,j);
}

Output:
changeValue-> a, b contain: 2 2
i and j is: 1,1
calling changeAndReturn()..
changeAndReturn -> a,b contain: 2 2
Now i and j contain: 1 2

Explanation:
Let's see how exactly the values are dealt. In the main() method, you are calling changeValue() method as

changeValue(i);

At this time, the value of i (which is 1) is being copied (Remember! xeroxed) and the xeroxed copy is what getting passed to the changeValue() method. Inside the changeValue() method, you get (receive) the passed value in the variable name "a". Note: Even if you have received the passed argument as the same name "i" in the function, the compiler would treat both of them differently!

Soon after you take a xerox copy of the value of the variable and use it for calling functions, the connection between the copied value and the original value is cut. There is no relation between those two values and /or variables.

Inside the method changeValue(), we do the following steps:

(i) receive the value passed in the variable whose name is 'a' (implicit)
(ii) declare an int variable named 'b'
(iii) increment the received value in its variable 'a' and assign the incremented value to 'b'

Since because the original value ('i' in main) does NOT hold any relationship with its xeroxcopy ('a' here), the changes you do in the called function (incrementing the value in changeValue()) does NOT reflect back.

That's why in the main after the function call returned, the printf statement prints the value both i and j contain 0. Once the function call is returned, the present focus is in main() function and now we are assigning the value of 'i' to 'j' which is 0 only. This clearly shows that there is NO effect on the variable 'i' even after calling the function changeValue() which does some change to it actually.

Just to have an effect, we have one more method called changeAndReturn() which changes the value and returns it. In the calling function (main()), we get the returned value and assign it to 'j'. That's why the second set of output shows the incremented value '2' for both 'i' and 'j'.

Pass-by-reference: The memory address of the variable is being passed instead of making a copy of the value. This holds good for C, C++ languages (as far as i know as such).

What are the effects?
Since you pass the memory address itself to the function and you obtain the value from the received memory address inside the called function, you get the full control over the value. That means, whatever change you do, it will be reflecting in the original variable in the calling function eventhough you do NOT return either the memory address or value back.

It is because, you have played around with the memory directly instead of values and in both the calling and called functions, the values are obtained and manipulated with respect to memory only. So the change is reflected back.

Let's see a sample program for pass-by-reference:

Sample Program for pass-by-reference:

void changeValue(int *int_ptr)
{
//doing an increment operation on the 'dereferenced' pointer
int b = ++(*int_ptr);
printf("changeValue -> a, b contain: %d,%d",a,b);
}

int main()
{
int i = 1;
int *int_ptr = &i;
printf("\ncalling changeValue()..");
//Note: we are passing the pointer to the function! (the 'address')
changeValue(int_ptr);
//assigning the value of 'i' to 'j'
int j = i;
printf("\ni and j is : %d,%d\n",i,j);
}

Output:
changeValue-> a, b contain: 2 2
calling changeValue()..
i and j is: 2,2

Explanation:

If you carefully look at the implementation and way of calling the function changeValue(), it actually receives a pointer to an integer! that means, we are passing the 'memory address' of an integer variable.

Inside the function, we do the following steps:

(i) receive the address of the integer variable in the name 'int_ptr' (the same name as in the calling function, here main(). But remember! for the compiler, they both are different!)
(ii) we declare an integer variable 'b'
(iii) we dereference the pointer variable ('dereferencing' means obtaining the value present in the location where the pointer is pointing to)
(iv) we increment the value being obtained by the dereferencing operation
Note: here the value is incremented directly in the memory location
(v) and assign the incremented value to the variable 'b'

One important thing is that, we do NOT return any value back to the calling function. But the changes happend in the memory location directly in the called function (changeValue()). Once the control comes back to the calling function (main()), we are still accessing the value in the same memory location through the original variable 'i' and assigning to 'j'.

That's why we see both i and j having the value '2'.

How to get the list of files in a directory and save it in a file

You may need to get the list of files inside a folder with the appropriate structures being maintained.

This tip will help you to get the complete list of filenames within a directory structure in Windows OS.

(1) Go to Command Prompt
(2) Navigate to any directory of your interest
(3) Type dir /b /s "Root-directory" > "filename.extension"

whereas

/b -> use bare format (no heading information or summary)
{summary is the date time info, size , file or directory attribute etc.}

/s -> displays file in specified directory and all subdirectories.

Root-directory -> is the directory from which you want the file list info
{if Root-directory is omitted it will process from the current directory}

> -> Redirection Operator or Symbol.
{the output of the command on its left would be sent to its right}

fileName.extension -> any file name with extension you want
{example. directory-structure.txt}

Make it Automated in a Batch File

You can even write a batch file with another line to open it in the
appropriate application.

dir /b /s "Root-directory" > "filename.extension"
notepad "filename.extension"

Save these two lines in a batchfile as ".bat" and run this batch file from command prompt. It would automatically save it in the file and gets opened in Notepad. You could use any other convenient applications to open as you wish.

Hope you may need not take screenshots for directory structure {if at all you had been doing so} ;-).