TCL programming introduction (III)

TCL programming introduction (III)

TCL built-in commands Built-in commands TCL provides the built-in functions described below. ... Indicates that the parameters are not specific: APPEND command: Append varname Value Append varname value...   Append the large number of values to the end of varname. If the variable does not exist, a new one is created. Example: Set I "AAA" Append I "BBB" "CCC" // I = aaabbbccc   Array command: Array subcommand arrayname Array subcommand arrayname arg...   This is a group of commands for vector operations. The second parameter is the subcommand name. Hypothesis: Set a (1) 1111 Set a (2) 2222 Set a (three) 3333   Take it as an example (tclsh is running in ). Array names arrayname Returns a list of array element names. Tclsh> array names 1 2 three Array size arrayname   Returns the number of elements in the array. Tclsh> array size 3   The following command is used for traversal. Arrry startsearch arrayname Initialize a traversal and return a traversal identifier (searchid) which is used in the following command. Array nextelement arrayname searchid Returns the elements in the next array. If no empty string is returned. Array anymore arrayname searchid 1 indicates that more elements exist. 0 indicates no. Array donesearch arrayname searchid End the traversal. Array nextelement arrayname searchid Returns the next element. Tclsh> array startsearch S-1-a Tclsh> array nextelement A s-1-a 1111 Tclsh> array nextelement A s-1-a 2222 Tclsh> array anymore a s-1-a 1 Tclsh? Array nextelement A s-1-a 3333 Tclsh & gt; array donesearch A s-1-a   Note that multiple traversal operations can be performed concurrently. Break command Break   Jump out of the latest loop. Case string in patlist body... Case string patlist body... Case string in {patlist body ...} Case string {patlist body ...}   Branch jump. For example: Case ABC in {A B} {puts 1} default {puts 2} A * {puts 3} Return 3. Case A in { {A B} {format 1} Default {Format 2} A * {Format 3} } Returns 1. Case XYZ { {A B} {Format 1} Default {Format 2} A * {Format 3} } Returns 2.   Note that default cannot be placed first. Supports matching characters of shell file names. Catch command Catch command varname Used to prevent interrupted execution due to errors. Run the command and tcl_ OK is returned each time, regardless of whether an error occurs. If an error occurs, 1 is returned, and 0 is returned. If varname is given, this is set to an error message. Note that varname is an existing variable. CD commands (such as shell) CD dirname   Convert the current working directory. If dirname is not provided, it is transferred to the home directory. Close fileid Disable the file descriptor. Concat arg... Concatenates parameters to generate a table. Concat a B {c d e} {f {g h }} Return 'a B c d e f {g h }" Continue   End the loop and continue the loop. EOF fileid For example, if fileid ends with 1, otherwise 0 is returned.