TCL:: How to print numbers from 10 to 1 using while loop.
Tcl includes two commands for looping, the while and for commands. Like the if statement, they evaluate their test the same way that the expr does. In this lesson we discuss the while command, and in the next lesson, the for command. In most circumstances where one of these commands can be used, the other can be used as well.
Tcl supports file handling with the help of the built in commands open, read, puts, gets, and close. A file represents a sequence of bytes, does not matter if it is a text file or binary file. Opens an existing text file for reading purpose and the file must exist. This is the default mode used when.
Tcl supports an iterated loop construct similar to the for loop in C. The for command in Tcl takes four arguments; an initialization, a test, an increment, and the body of code to evaluate on each pass through the loop. The syntax for the for command is:. for start test next body; During evaluation of the for command, the start code is evaluated once, before any other arguments are evaluated.
The break statement in Tcl language is used for terminating a loop. When the break statement is encountered inside a loop, the loop is immediately terminated and program control resumes at the next statement following the loop. If you are using nested loops (i.e., one loop inside another loop), the break statement will stop the execution of the innermost loop and start executing the next line.
The foreach command implements a loop where the loop variable(s) take on values from one or more lists. In the simplest case there is one loop variable, varname, and one list, list, that is a list of values to assign to varname. The body argument is a Tcl script.
An if statement can be followed by an optional else statement, which executes when the Boolean expression is false. If the Boolean expression evaluates to true, then the if block of code will be executed, otherwise else block of code will be executed. Tcl language uses the expr command internally and hence it's not required for us to use expr.
Tcl provides an easy way to open and read the lines of a file. Check out these code snippets that demonstrate how to read and write files with Tcl programming language.
C Program to Display Characters from A to Z Using Loop In this example, you will learn to print all the letters of the English alphabet.
If you use a variable to keep count inside a while loop, you can use the incr command to increment that variable. You can skip to the end of a loop by using the continue command; the break command exits the loop. The following Tcl script uses a while loop to add all the numbers from 1 to 10, except 5.
Tcl provides several methods to read from and write to files on disk. The simplest methods to access a file are via gets and puts. When there is a lot of data to be read, however, it is sometimes more efficient to use the read command to load an entire file, and then parse the file into lines with the split command.
Tcl lists. In this part of the Tcl tutorial, we will talk about lists. Computer programs work with data. Working with groups of data is a basic programming operation.
The while statement is used to execute a list of commands repeatedly. 1 The while loop syntax. 2 while loop Example. 2.1 Using ( (expression)) Format With The While Loop. 2.2 Reading A Text File. 2.2.1 Reading A Text File With Separate Fields. 3 External Links. The while loop syntax. while ( condition ) do command1 command2.
By default, files opened for writing by Tcl are block buffered. You can actually control the buffering with Extended Tcl commands, but the simplest approach is to use the flush command after a write. Flushing is generally unnecessary when working with files (and in fact will slow you down), but it's crucial when doing IPC. Current Working Directory.
