Queue/Usage: Difference between revisions
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The entries in the stack may be anything, including "nulls". |
The entries in the stack may be anything, including "nulls". |
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<lang rexx>/*REXX program demonstrates |
<lang rexx>/*REXX program demonstrates four queueing operations: push, pop, empty, query. */ |
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say '══════════════════════════════════ Pushing five values to the stack.' |
say '══════════════════════════════════ Pushing five values to the stack.' |
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do j=1 for 4 /*loop to PUSH four values. |
do j=1 for 4 /*a DO loop to PUSH four values. */ |
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call push j*10 /*PUSH (aka enqueue to stack). |
call push j * 10 /*PUSH (aka: enqueue to the stack).*/ |
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say 'pushed value:' j*10 /*echo the pushed value. */ |
say 'pushed value:' j * 10 /*echo the pushed value. */ |
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if j\==3 then iterate /* |
if j\==3 then iterate /*Not equal 3? Then use a new number.*/ |
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call push /*PUSH (aka enqueue to stack). |
call push /*PUSH (aka: enqueue to the stack).*/ |
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say 'pushed a "null" value.' /*echo what was pushed |
say 'pushed a "null" value.' /*echo what was pushed to the stack. */ |
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end /*j*/ |
end /*j*/ |
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say '══════════════════════════════════ Quering the stack (number of entries).' |
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say queued() ' entries in the stack.' |
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say '══════════════════════════════════ Popping all values from the stack.' |
say '══════════════════════════════════ Popping all values from the stack.' |
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do |
do k=1 while \empty() /*EMPTY (returns TRUE [1] if empty).*/ |
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call pop /*POP (aka dequeue from stack).*/ |
call pop /*POP (aka: dequeue from the stack).*/ |
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say |
say k': popped value=' result /*echo the popped value. */ |
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end /* |
end /*k*/ |
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say '══════════════════════════════════ The stack is now empty.' |
say '══════════════════════════════════ The stack is now empty.' |
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exit /*stick a fork in it, we're done.*/ |
exit /*stick a fork in it, we're all done. */ |
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/*──────────────────────────────────────────────────────────────────────────────────────*/ |
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/*──────────────────────────────────subroutines/functions/operators. */ |
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push: queue arg(1); |
push: queue arg(1); return /*(The REXX QUEUE is FIFO.) */ |
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pop: procedure; pull x; return x /*REXX PULL removes a stack item*/ |
pop: procedure; parse pull x; return x /*REXX PULL removes a stack item. */ |
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empty: return queued()==0 /*returns the status of the stack*/</lang> |
empty: return queued()==0 /*returns the status of the stack. */</lang> |
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{{out|output|text=:}} |
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<pre> |
<pre> |
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══════════════════════════════════ Pushing five values to the stack. |
══════════════════════════════════ Pushing five values to the stack. |
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pushed a "null" value. |
pushed a "null" value. |
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pushed value: 40 |
pushed value: 40 |
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══════════════════════════════════ Quering the stack (number of entries). |
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5 entries in the stack. |
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══════════════════════════════════ Popping all values from the stack. |
══════════════════════════════════ Popping all values from the stack. |
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1: popped value= 10 |
1: popped value= 10 |
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