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Conditional Flow Control Part-III

Sunday, 27 February 2022 16:00 Semicon Editor 01

File Iterative Control
In e the way we open and read ASCII files is slightly different then C and C++. There are two types of looping constructs that are provided to help with handling ASCII files.

for each line in file

for each file matching

for each line in file
Executes the action block for each line in the text file file-name. Inside the block, it (or optional name) refers to the current line (as string) without the final "\n" (the final new line character, CR).

Syntax :

for each [line] [(name)] in file file-name-exp [do] {action; ...}

Example - for each line in file

Lets consider a ASCII file file.txt containing below lines

Lets write a e program to read this file and print it

1 <'

2 extend sys {

3 run() is also {

4 for each line in file "file.txt" {

5 out (it);

6 };

7 };

8 };

9 '>

Simulator Output

This is first line

This is second line

This is third line

for each file matching

For each file (in the file search path) whose name matches file-name-exp execute the action block. Inside the block, it (or optional name) refers to the matching file name.

Syntax

for each file [(name)] matching file-name-exp [do] {action; ...}

Example - for each file matching

1 <'

2 extend sys {

3 run() is also {

4 for each file (file_name) matching "f*.txt" {

5 outf("Found file %s\n",file_name);

6 for each line in file file_name {

7 out (it);

8 };

9 };

10 };

11 };

12 '>

Simulator Output

Found file file.txt

This is first line

This is second line

This is third line

Controlling the Program Flow

The actions described in this section are used to alter the flow of the program in places where the flow would otherwise continue differently. The e language provides the following actions for controlling the program flow:

break
continue
break
Breaks the execution of the nearest enclosing iterative action (for or while). When a break action is encountered within a loop, the execution of actions within the loop is terminated, and the next action to be executed is the first one following the loop.

Syntax

break

continue

Stops the execution of the nearest enclosing iteration of a for or a while loop, and continues with the next iteration of the same loop. When a continue action is encountered within a loop, the current iteration of the loop is aborted, and execution continues with the next iteration of the same loop.

You cannot place continue actions outside the scope of a loop

Syntax

Continue

Example - break and continue 1 <'

2 extend sys {

3 run() is also {

4 var i : int = 0;

5 var j : int = 0;

6 for {i=0; i < 15; i = i + 1} do {

7 outf("Current value of i : %d\n",i);

8 outf("Current value of j : %d\n",j);

9 if ( i < 3) {