实战Tcl和TK程序设计 第一章　TCL基础

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 octal digits (0-7).

\xhh

Hexadecimal specification of character code. 1 or 2 hex digits. Be careful when using this in a string of characters, because all hexadecimal characters following the \x will be consumed, but only the last 2 will specify the value.

\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.

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.

== != eq ne

Equal, not equal, string equal (Tcl 8.4), string not equal (Tcl 8.4).

&

Bitwise AND.

^

Bitwise XOR.

|

Bitwise OR.

&&

Logical AND.

||

Logical OR.

x?y:z

If x then y else z.

Table 1-3. Built-in math functions

acos(x)

Arccosine of x.

asin(x)

Arcsine of x.

atan(x)

Arctangent 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.

wide(x)

Promote x to a wide (64-bit) integer. (Tcl 8.4)

Table 1-4. Built-in Tcl commands

Command

Pg.

Description

after

228

Schedule a Tcl command for later execution.

append

56

Append arguments to a variable's value. No spaces added.

array

97

Query array state and search through elements.

binary

59

Convert between strings and binary data.

break

83

Exit loop prematurely.

catch

83

Trap errors.

cd

122

Change working directory.

clock

183

Get the time and format date strings.

close

121

Close an open I/O stream.

concat

65

Concatenate arguments with spaces between. Splices lists.

console

29

Control the console used to enter commands interactively.

continue

83

Continue with next loop iteration.

error

85

Raise an error.

eof

116

Check for end of file.

eval

130

Concatenate arguments and evaluate them as a command.

exec

105

Fork and execute a UNIX program.

exit

124

Terminate the process.

expr

6

Evaluate a math expression.

fblocked

233

Poll an I/O channel to see if data is ready.

fconfigure

231

Set and query I/O channel properties.

fcopy

250

Copy from one I/O channel to another.

file

108

Query the file system.

fileevent

229

Register callback for event-driven I/O.

flush

116

Flush output from an I/O stream's internal buffers.

for

82

Loop construct similar to C for statement.

foreach

79

Loop construct over a list, or lists, of values.

format

56

Format a string similar to C sprintf.

gets

119

Read a line of input from an I/O stream.

glob

122

Expand a pattern to matching file names.

global

90

Declare global variables.

history

196

Use command-line history.

if

76

Test a condition. Allows else and elseif clauses.

incr

12

Increment a variable by an integer amount.

info

186

Query the state of the Tcl interpreter.

interp

292

Create additional Tcl interpreters.

join

72

Concatenate list elements with a given separator string.

lappend

66

Add elements to the end of a list.

lindex

68

Fetch an element of a list.

linsert

68

Insert elements into a list.

list

65

Create a list out of the arguments.

llength

68

Return the number of elements in a list.

load

697

Load shared libraries that define Tcl commands.

lrange

68

Return a range of list elements.

lreplace

68

Replace elements of a list.

lsearch

69

Search for an element of a list that matches a pattern.

lset

62

Set an element in a list. (Tcl 8.4)

lsort

70

Sort a list.

namespace

213

Create and manipulate namespaces.

open

116

Open a file or process pipeline for I/O.

package

175

Provide or require code packages.

pid

124

Return the process ID.

proc

87

Define a Tcl procedure.

puts

119

Output a string to an I/O stream.

pwd

122

Return the current working directory.

read

120

Read blocks of characters from an I/O stream.

regexp

158

Match regular expressions.

regsub

162

Substitute based on regular expressions.

rename

88

Change the name of a Tcl command.

return

86

Return a value from a procedure.

scan

58

Parse a string according to a format specification.

seek

121

Set the seek offset of an I/O stream.

set

5

Assign a value to a variable.

socket

239

Open a TCP/IP network connection.

source

26

Evaluate the Tcl commands in a file.

split

71

Chop a string up into list elements.

string

49

Operate on strings.

subst

140

Substitute embedded commands and variable references.

switch

77

Test several conditions.

tell

121

Return the current seek offset of an I/O stream.

time

202

Measure the execution time of a command.

trace

193

Monitor variable assignments.

unknown

178

Handle unknown commands.

unset

13

Delete variables.

uplevel

138

Execute a command in a different scope.

upvar

91

Reference a variable in a different scope.

variable

207

Declare namespace variables.

vwait

230

Wait for a variable to be modified.

while

79

Loop until a boolean expression is false.