===MMBasic - Create/Manipulate Stack, Queue or List===
{{ :migratedattachments:mmbasic_original:stack_queue_list_utilities.zip?linkonly}} 

<code>Stack, Queue and List Routines for Strings and Numeric values
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Code is included in the zipped attachment

String Operations
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S.STACK.CREATE string$,width

Create a string as a holder for multiple substrings of width characters long for use as a Last 
In, First Out (LIFO) stack. Maximum number of substrings is width x number of substrings =< 250. 
Eg. max 25 of 10 character longs strings. Strings of less than width are right justified and 
padded with spaces.

Routine returns with string$ set up as the holder with the width in character positions 
1 and 2 (maximum 99) and a pointer to the bottom of the stack + 1 in positions 3, 4 and 5.


S.STACK.PUSH string$,data$

Push data$ onto stack string$. If data$ is shorter than width, data$ is right justified and 
padded with spaces.


S.STACK.POP$(string$)

Function to pop the top substring off the stack string$.

All string stack operations are checked for overflow, underflow or substrings too wide.

Queue Operations
----------------

S.QUEUE.CREATE string$,width

Create a string as a holder for multiple substrings of width characters long for use as a 
First In, First Out (FIFO) queue. Maximum number of substrings is width x number of 
substrings =< 250. Eg. max 25 of 10 character longs strings. Strings of less than width 
are right justified and padded with spaces.

Routine returns with string$ set up as the holder with the width in character positions 
1 and 2 (maximum 99) and a pointer to the bottom of the stack + 1 in positions 3, 4 and 5.

S.QUEUE.PUSH string$,data$

Push data$ onto queue string$. If data$ is shorter than width, data$ is right justified and 
padded with spaces.

S.QUEUE.PULL$(string$)

Function to pop the bottom (first) substring off the queue string$.
All string queue operations are checked for overflow, underflow or substrings too wide.

List Operations
---------------

S.LIST.CREATE string$,width

Create a string as a holder for multiple substrings of width characters long for use as a 
random access list. Maximum number of substrings is width x number of substrings =< 250. 
Eg. max 25 of 10 character longs strings. Strings of less than width are right justified 
and padded with spaces.

Routine returns with string$ set up as the holder with the width in character positions 
1 and 2 (maximum 99) and a pointer to the bottom of the list + 1 in positions 3, 4 and 5.


S.LIST.ADD string$,data$

Add data$ onto list string$ at the bottom. If data$ is shorter than width, data$ is right
 justified and padded with spaces.


S.LIST.FILL string$,file$

Add data$ onto list string$ at the bottom from text file file$. Text file file$ must have 
each entry of length width or less and terminated with CRLF.  CRLF is stripped prior to 
data$ being added to list. If data$ is shorter than width, data$ is right justified and 
padded with spaces.


S.LIST.GET$(string$,index)

Function to return the list entry pointed to by index. The list is not modified.
All string list operations are checked for overflow or substrings too wide.

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Commands for numeric manipulation in a stack.

Numeric Operations
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N.STACK.CREATE string$,width

Create a string as a holder for multiple substrings of numeric variables for use as a 
Last In, First Out (LIFO) stack. Maximum number of numeric values pushed onto the 
stack is 62.

Routine returns with string$ set up as the holder with the width in character positions
 1 and 2 (always 4) and a pointer to the bottom of the stack + 1 in positions 3, 4 and 5.


N.STACK.PUSH string$,data

Push numeric data onto stack string$.


N.STACK.POP(string$)

Function to pop the top numeric value off the stack string$.


N.STACK.AVERAGE(string$)

Function to return the average of all the numerical values on the stack.
All operations are checked for overflow, underflow or substrings too wide.

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Doug Pankhurst