Reference

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	Practical Programming in Tcl & Tk, Third Edition By Brent B. Welch
	Table of Contents
	Chapter 1.  Tcl Fundamentals

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Backslash Sequences

Table 1-1. Backslash sequences.

\a	Bell. (0x7)
\b	Backspace. (0x8)
\f	Form feed. (0xc)
\n	Newline. (0xa)
\r	Carriage return. (0xd)
\t	Tab. (0x9)
\v	Vertical tab. (0xb)
\<newline>	Replace the newline and the leading white space on the next line with a space.
\\	Backslash. ('\')
\ooo	Octal specification of character code. 1, 2, or 3 digits.
\xhh	Hexadecimal specification of character code. 1 or 2 digits.
\uhhhh	Hexadecimal specification of a 16-bit Unicode character value. 4 hex digits.
\c	Replaced with literal c if c is not one of the cases listed above. In particular, \$, \", \{, \}, \], and \[ are used to obtain these characters.

Arithmetic Operators

Table 1-2. Arithmetic operators from highest to lowest precedence.

- ~ !	Unary minus, bitwise NOT, logical NOT.
* / %	Multiply, divide, remainder.
+ -	Add, subtract.
<< >>	Left shift, right shift.
< > <= >=	Comparison: less, greater, less or equal, greater or equal.
== !=	Equal, not equal.
&	Bitwise AND.
^	Bitwise XOR.
|	Bitwise OR.
&&	Logical AND.
||	Logical OR.
x?y:z	If x then y else z.

Built-in Math Functions

Table 1-3. Built-in math functions.

acos(x)	Arc cosine of x.
asin(x)	Arc sine of x.
atan(x)	Arc tangent of x.
atan2(y,x)	Rectangular (x,y) to polar (r,th). atan2 gives th.
ceil(x)	Least integral value greater than or equal to x.
cos(x)	Cosine of x.
cosh(x)	Hyperbolic cosine of x.
exp(x)	Exponential, ex.
floor(x)	Greatest integral value less than or equal to x.
fmod(x,y)	Floating point remainder of x/y.
hypot(x,y)	Returns sqrt(x*x + y*y). r part of polar coordinates.
log(x)	Natural log of x.
log10(x)	Log base 10 of x.
pow(x,y)	x to the y power, xy.
sin(x)	Sine of x.
sinh(x)	Hyperbolic sine of x.
sqrt(x)	Square root of x.
tan(x)	Tangent of x.
tanh(x)	Hyperbolic tangent of x.
abs(x)	Absolute value of x.
double(x)	Promote x to floating point.
int(x)	Truncate x to an integer.
round(x)	Round x to an integer.
rand()	Return a random floating point value between 0.0 and 1.0.
srand(x)	Set the seed for the random number generator to the integer x.

Core Tcl Commands

The pages listed in Table 1-4 give the primary references for the command.

Table 1-4. Built-in Tcl commands.

Command	Pg.	Description
after	218	Schedule a Tcl command for later execution.
append	51	Append arguments to a variable's value. No spaces added.
array	91	Query array state and search through elements.
binary	54	Convert between strings and binary data.
break	77	Exit loop prematurely.
catch	77	Trap errors.
cd	115	Change working directory.
clock	173	Get the time and format date strings.
close	115	Close an open I/O stream.
concat	61	Concatenate arguments with spaces between. Splices lists.
console	28	Control the console used to enter commands interactively.
continue	77	Continue with next loop iteration.
error	79	Raise an error.
eof	109	Check for end of file.
eval	122	Concatenate arguments and evaluate them as a command.
exec	99	Fork and execute a UNIX program.
exit	116	Terminate the process.
expr	6	Evaluate a math expression.
fblocked	223	Poll an I/O channel to see if data is ready.
fconfigure	221	Set and query I/O channel properties.
fcopy	239	Copy from one I/O channel to another.
file	102	Query the file system.
fileevent	219	Register callback for event-driven I/O.
flush	109	Flush output from an I/O stream's internal buffers.
for	76	Loop construct similar to C for statement.
foreach	73	Loop construct over a list, or lists, of values.
format	52	Format a string similar to C sprintf.
gets	112	Read a line of input from an I/O stream.
glob	115	Expand a pattern to matching file names.
global	84	Declare global variables.
history	185	Use command-line history.
if	70	Conditional command. Allows else and elseif clauses.
incr	12	Increment a variable by an integer amount.
info	176	Query the state of the Tcl interpreter.
interp	276	Create additional Tcl interpreters.
join	65	Concatenate list elements with a given separator string.
lappend	61	Add elements to the end of a list.
lindex	63	Fetch an element of a list.
linsert	64	Insert elements into a list.
list	61	Create a list out of the arguments.
llength	63	Return the number of elements in a list.
load	609	Load shared libraries that define Tcl commands.
lrange	63	Return a range of list elements.
lreplace	64	Replace elements of a list.
lsearch	64	Search for an element of a list that matches a pattern.
lsort	65	Sort a list.
namespace	203	Create and manipulate namespaces.
open	110	Open a file or process pipeline for I/O.
package	165	Provide or require code packages.
pid	116	Return the process ID.
proc	81	Define a Tcl procedure.
puts	112	Output a string to an I/O stream.
pwd	115	Return the current working directory.
read	113	Read blocks of characters from an I/O stream.
regexp	148	Match regular expressions.
regsub	152	Substitute based on regular expressions.
rename	82	Change the name of a Tcl command.
return	80	Return a value from a procedure.
scan	54	Parse a string according to a format specification.
seek	114	Set the seek offset of an I/O stream.
set	5	Assign a value to a variable.
socket	228	Open a TCP/IP network connection.
source	26	Evaluate the Tcl commands in a file.
split	65	Chop a string up into list elements.
string	45	Operate on strings.
subst	132	Substitute embedded commands and variable references.
switch	71	Multi-way branch.
tell	114	Return the current seek offset of an I/O stream.
time	191	Measure the execution time of a command.
trace	183	Monitor variable assignments.
unknown	167	Handle unknown commands.
unset	13	Delete variables.
uplevel	130	Execute a command in a different scope.
upvar	85	Reference a variable in a different scope.
variable	197	Declare namespace variables.
vwait	220	Wait for a variable to be modified.
while	73	Loop until a boolean expression is false.

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