Saving and quiting at Vim

If like me you wonder how the hell to write in Vim, make sure you are in the insert mode(The mode that you can actually write). You can do that by pressing i.

After finishing, you are supposed to save what you have written. So you press Esc button and then write :w. Then you can simply write :q to quit.

Pay attention that you can write commands(:w, :q, ...) in the command line and you can go to command line by pressing Esc button in Vim.

Good luck, it is a powerful editor, but as me, you got a long way a head to learn how to work with it.

Showing Line Number while editing a file in Vi or Vim

While editing a document at Unix/Linux, press Esc button type

:set number

to have line numbers beside your editor. If you are tired of line numbers, enter the following to turn them off:

:set nonumber

Crazy about old games ? Try DosBox

DOSBox is an emulator which emulates an IBM PC compatible computer running MS-DOS. It is intended especially for use with old PC games. DOSBox is free software.

instanceof example in Java

public class MainClass {
public static void main(String[] a) {

String s = "Hello";
if (s instanceof java.lang.String) {
System.out.println("is a String");
}
}

}

Installing Windows 7 from USB Drive

This guide works 100% for Vista & Windows 7 unlike most of the guides out there. I have seen many sites/blogs that have “Install Vista from USB guide” but either with incomplete steps or not working guide. I have also seen some guides that don’t’ use proper commands in this guide. After spending many hours I have come up with this 100% working guide.

I just did this method on one of my friends machine and installed the new Windows 7 BETA. The main advantage is that by using USB drive you will be able to install Windows 7/Vista in just 15 minutes. You can also use this bootable USB drive on friend’s computer who doesn’t have a DVD optical drive.

The method is very simple and you can use without any hassles. Needless to say that your motherboard should support USB Boot feature to make use of the bootable USB drive.

Requirements:

*USB Flash Drive (Minimum 4GB)

*Windows 7 or Vista installation files.

Follow the below steps to create bootable Windows 7/Vista USB drive using which you can install Windows 7/Vista easily.

1. Plug-in your USB flash drive to USB port and move all the contents from USB drive to a safe location on your system.

2. Open Command Prompt with admin rights. Use any of the below methods to open Command Prompt with admin rights.

*Type cmd in Start menu search box and hit Ctrl+ Shift+ Enter.

Or

*Go to Start menu > All programs > Accessories, right click on Command Prompt and select Run as administrator.

3. You need to know about the USB drive a little bit. Type in the following commands in the command prompt:

First type DISKPART and hit enter to see the below message.

Next type LIST DISK command and note down the Disk number (ex: Disk 1) of your USB flash drive. In the below screenshot my Flash Drive Disk no is Disk 1.

4. Next type all the below commands one by one. Here I assume that your disk drive no is “Disk 1”.If you have Disk 2 as your USB flash drive then use Disk 2.Refer the above step to confirm it.

So below are the commands you need to type and execute one by one:

SELECT DISK 1

CLEAN

CREATE PARTITION PRIMARY

SELECT PARTITION 1

ACTIVE

FORMAT FS=NTFS

(Format process may take few seconds)

ASSIGN

EXIT

Don’t close the command prompt as we need to execute one more command at the next step. Just minimize it.

5. Next insert your Windows7/Vista DVD into the optical drive and check the drive letter of the DVD drive. In this guide I will assume that your DVD drive letter is “D” and USB drive letter is “H” (open my computer to know about it).

6. Maximize the minimized Command Prompt in the 4th step.Type the following command now:

D:CD BOOT and hit enter.Where “D” is your DVD drive letter.

CD BOOT and hit enter to see the below message.

7. Type another command given below to update the USB drive with BOOTMGR compatible code.

BOOTSECT.EXE/NT60 H:

Where “H” is your USB drive letter. Once you enter the above command you will see the below message. You might face an error – Access Denied for no priviledge in copying the bootsector to device. Solution to this is to just Exit the Command Prompt and Run it again (still need to Run as Administrator).

8. Copy your Windows 7/Vista DVD contents to the USB flash drive.

9. Your USB drive is ready to boot and install Windows 7/Vista. Only thing you need to change the boot priority at the BIOS to USB from the HDD or CD ROM drive. I won’t explain it as it’s just the matter the changing the boot priority or enabling the USB boot option in the BIOS.

Note: If you are not able to boot after following this guide means you haven’t set the BIOS priority to USB. If you got any problem in following this guide feel free to ask questions by leaving comment.

*** Main article taken from Source, but modified.

How to run Remote Desktop from CMD or RUN

To run Remote Desktop from CMD(windows command line) or run in start menu write :

mstsc.exe

or just simply

mstsc

user name @ Linux getenv("USER")

C Programming tips : getenv("USER"); is a method that returns a string that is your Linux user name(that you are logged in the terminal)

STRFTIME, your gateway to date and time in C !!!

"strftime" converts information from a time structure to a string form, and writes the string into the memory area pointed to by "string".

The "format" string tells what information is required and how it should be presented. It is much like the format string used by "printf". The format string consists of ordinary characters (which are copied directly into "*string") and placeholders consisting of a '%' followed by a letter. For a list over placeholders visit here.

concating two string in C

strcat takes two char * arguments and returns the concatenated string as a char *. Here's a simple use of strcat:

#include 
#include 

int main() {
 char str1[50] = "Hello ";
 char str2[] = "World";

 strcat(str1, str2);

 printf("str1: %s\n", str1);

 return 0;
}

Output:

str1: Hello World

Reading and Writing a pointer of continously memory to the file in C

int _backItUp(){
FILE * hFile;
//************************
char *_fileName;
_fileName = getenv("USER");
char buffer[200];
struct timeval tv;
time_t curtime;
gettimeofday(&tv, NULL);
curtime=tv.tv_sec;
strftime(buffer,30,"%Y%m%d_%H%M",localtime(&curtime));
//"%m-%d-%Y %T"
strcat(_fileName,"_");
strcat(_fileName,buffer);
strcat(_fileName,".bak");
//*******************************
hFile = fopen( _fileName, "w");
if (hFile == NULL){
// Error, file not found
printf("*** Failed to open the file ***\n");
return FAILED;
}//end of if
else{
// Process & close file
int nWritten = fwrite(allocatedMem, sizeof(unsigned char), (200*sizeof(SmsDB))+((75)*sizeof(unsigned char))+((200*3)*sizeof(dBlock)), hFile);
printf("*** Taking backup ***\n");
fclose(hFile);
}//end of else
return SUCCESS;
}//end of backItUp()

int _readItUp(){
FILE * hFile;
hFile = fopen( ___fileName, "r");
if (hFile == NULL){
// Error, file not found
printf("*** Failed to open the file ***\n");
return FAILED;
}//end of if
else{
// Process & close file
int nRead = fread(allocatedMem, sizeof(unsigned char), (200*sizeof(SmsDB))+((75)*sizeof(unsigned char))+((200*3)*sizeof(dBlock)), hFile);
fclose(hFile);
}//end of else
return SUCCESS;
}//end of _readItUp()

CTRL+D and CTRL+L signal handling

Code:

#include 

int main()
{
 char c;
 printf("Write: ");
 scanf("%c", &c);
 if(c == 0x0C) printf("ctrl+L was entered\n");
 return 1;
}

but the execution of this doesnt..

Code:

#include 

int main()
{
 char c;
 printf("Write: ");
 scanf("%c", &c);
 if(c == 0x04) printf("ctrl+D was entered\n");
 return 1;
}

ASCII Character Chart with Decimal, Binary and Hexadecimal Conversions

Character Name	Char	Code	Decimal	Binary	Hex
Null	NUL	Ctrl @	0	00000000	00
Start of Heading	SOH	Ctrl A	1	00000001	01
Start of Text	STX	Ctrl B	2	00000010	02
End of Text	ETX	Ctrl C	3	00000011	03
End of Transmit	EOT	Ctrl D	4	00000100	04
Enquiry	ENQ	Ctrl E	5	00000101	05
Acknowledge	ACK	Ctrl F	6	00000110	06
Bell	BEL	Ctrl G	7	00000111	07
Back Space	BS	Ctrl H	8	00001000	08
Horizontal Tab	TAB	Ctrl I	9	00001001	09
Line Feed	LF	Ctrl J	10	00001010	0A
Vertical Tab	VT	Ctrl K	11	00001011	0B
Form Feed	FF	Ctrl L	12	00001100	0C
Carriage Return	CR	Ctrl M	13	00001101	0D
Shift Out	SO	Ctrl N	14	00001110	0E
Shift In	SI	Ctrl O	15	00001111	0F
Data Line Escape	DLE	Ctrl P	16	00010000	10
Device Control 1	DC1	Ctrl Q	17	00010001	11
Device Control 2	DC2	Ctrl R	18	00010010	12
Device Control 3	DC3	Ctrl S	19	00010011	13
Device Control 4	DC4	Ctrl T	20	00010100	14
Negative Acknowledge	NAK	Ctrl U	21	00010101	15
Synchronous Idle	SYN	Ctrl V	22	00010110	16
End of Transmit Block	ETB	Ctrl W	23	00010111	17
Cancel	CAN	Ctrl X	24	00011000	18
End of Medium	EM	Ctrl Y	25	00011001	19
Substitute	SUB	Ctrl Z	26	00011010	1A
Escape	ESC	Ctrl [	27	00011011	1B
File Separator	FS	Ctrl \	28	00011100	1C
Group Separator	GS	Ctrl ]	29	00011101	1D
Record Separator	RS	Ctrl ^	30	00011110	1E
Unit Separator	US	Ctrl _	31	00011111	1F
Space			32	00100000	20
Exclamation Point	!	Shift 1	33	00100001	21
Double Quote	"	Shift ‘	34	00100010	22
Pound/Number Sign	#	Shift 3	35	00100011	23
Dollar Sign	$	Shift 4	36	00100100	24
Percent Sign	%	Shift 5	37	00100101	25
Ampersand	&	Shift 7	38	00100110	26
Single Quote	‘	‘	39	00100111	27
Left Parenthesis	(	Shift 9	40	00101000	28
Right Parenthesis	)	Shift 0	41	00101001	29
Asterisk	*	Shift 8	42	00101010	2A
Plus Sign	+	Shift =	43	00101011	2B
Comma	,	,	44	00101100	2C
Hyphen / Minus Sign	-	-	45	00101101	2D
Period	.	.	46	00101110	2E
Forward Slash	/	/	47	00101111	2F
Zero Digit	0	0	48	00110000	30
One Digit	1	1	49	00110001	31
Two Digit	2	2	50	00110010	32
Three Digit	3	3	51	00110011	33
Four Digit	4	4	52	00110100	34
Five Digit	5	5	53	00110101	35
Six Digit	6	6	54	00110110	36
Seven Digit	7	7	55	00110111	37
Eight Digit	8	8	56	00111000	38
Nine Digit	9	9	57	00111001	39
Colon	:	Shift ;	58	00111010	3A
Semicolon	;	;	59	00111011	3B
Less-Than Sign	<	Shift ,	60	00111100	3C
Equals Sign	=	=	61	00111101	3D
Greater-Than Sign	>	Shift .	62	00111110	3E
Question Mark	?	Shift /	63	00111111	3F
At Sign	@	Shift 2	64	01000000	40
Capital A	A	Shift A	65	01000001	41
Capital B	B	Shift B	66	01000010	42
Capital C	C	Shift C	67	01000011	43
Capital D	D	Shift D	68	01000100	44
Capital E	E	Shift E	69	01000101	45
Capital F	F	Shift F	70	01000110	46
Capital G	G	Shift G	71	01000111	47
Capital H	H	Shift H	72	01001000	48
Capital I	I	Shift I	73	01001001	49
Capital J	J	Shift J	74	01001010	4A
Capital K	K	Shift K	75	01001011	4B
Capital L	L	Shift L	76	01001100	4C
Capital M	M	Shift M	77	01001101	4D
Capital N	N	Shift N	78	01001110	4E
Capital O	O	Shift O	79	01001111	4F
Capital P	P	Shift P	80	01010000	50
Capital Q	Q	Shift Q	81	01010001	51
Capital R	R	Shift R	82	01010010	52
Capital S	S	Shift S	83	01010011	53
Capital T	T	Shift T	84	01010100	54
Capital U	U	Shift U	85	01010101	55
Capital V	V	Shift V	86	01010110	56
Capital W	W	Shift W	87	01010111	57
Capital X	X	Shift X	88	01011000	58
Capital Y	Y	Shift Y	89	01011001	59
Capital Z	Z	Shift Z	90	01011010	5A
Left Bracket	[	[	91	01011011	5B
Backward Slash	\	\	92	01011100	5C
Right Bracket	]	]	93	01011101	5D
Caret	^	Shift 6	94	01011110	5E
Underscore	_	Shift -	95	01011111	5F
Back Quote	`	`	96	01100000	60
Lower-case A	a	A	97	01100001	61
Lower-case B	b	B	98	01100010	62
Lower-case C	c	C	99	01100011	63
Lower-case D	d	D	100	01100100	64
Lower-case E	e	E	101	01100101	65
Lower-case F	f	F	102	01100110	66
Lower-case G	g	G	103	01100111	67
Lower-case H	h	H	104	01101000	68
Lower-case I	I	I	105	01101001	69
Lower-case J	j	J	106	01101010	6A
Lower-case K	k	K	107	01101011	6B
Lower-case L	l	L	108	01101100	6C
Lower-case M	m	M	109	01101101	6D
Lower-case N	n	N	110	01101110	6E
Lower-case O	o	O	111	01101111	6F
Lower-case P	p	P	112	01110000	70
Lower-case Q	q	Q	113	01110001	71
Lower-case R	r	R	114	01110010	72
Lower-case S	s	S	115	01110011	73
Lower-case T	t	T	116	01110100	74
Lower-case U	u	U	117	01110101	75
Lower-case V	v	V	118	01110110	76
Lower-case W	w	W	119	01110111	77
Lower-case X	x	X	120	01111000	78
Lower-case Y	y	Y	121	01111001	79
Lower-case Z	z	Z	122	01111010	7A
Left Brace	{	Shift [	123	01111011	7B
Vertical Bar	|	Shift \	124	01111100	7C
Right Brace	}	Shift ]	125	01111101	7D
Tilde	~	Shift `	126	01111110	7E
Delta	D		127	01111111	7F

Source : http://www.pcguide.com/res/tablesASCII-c.html