DataType:stack

A stack is a last-in, first-out data structure. Items inserted (Pushed) are placed on the 'top' of the queue. Items removed (Popped) are also removed from the 'top'.

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This Data Type is referenced in MQ2Collections, and accessed by Top-Level Object(s): stack

Members

Type	Member	Description
bool	IsEmpty	True if Count = 0, False otherwise.
	Push[string]	True if the item was pushed successfully.
int	Count	Number of items inserted onto the stack.
string	Peek	False is returned if IsEmpty is true.
	Pop

Examples

Sub StackTest
    /declare s stack

    /echo 'Starting Stack Test'
    /echo 'Stack is Empty: ${s.IsEmpty}'
    
    | Push entries on the stack and pop them off.
    | Note: entries are inserted (Pushed) in and removed
    | (Popped) in reverse order. That is, Pushing A, B, C, D, E
    | and then Popping them will return E, D, C, D, A.

    /echo 'Pushing items onto the Stack.'
    /if (!${s.Push[A]}) {
    	/echo 'Stack Push of A failed.'
	/endmacro
    }
    /if (!${s.Push[B]}) {
    	/echo 'Stack Push of B failed.'
	/endmacro
    }
    /if (!${s.Push[C]}) {
    	/echo 'Stack Push of C failed.'
	/endmacro
    }
    /if (!${s.Push[D]}) {
    	/echo 'Stack Push of D failed.'
	/endmacro
    }
    /if (!${s.Push[E]}) {
    	/echo 'Stack Push of E failed.'
	/endmacro
    }

    /declare count int
    /varset count ${s.Count}
    /if (${count} != 5) {
    	/echo 'Stack count is: ${count} and should be 5.'
	/endmacro
    }

    /echo 'Stack is Empty: ${s.IsEmpty}'
    
    | Peek at the top item:
    /echo 'Top item is: ${s.Peek}'
    
    | Pop items off the stack.

    /echo 'Popping item off stack: ${s.Pop}'
    /echo 'Popping item off stack: ${s.Pop}'
    /echo 'Popping item off stack: ${s.Pop}'
    /echo 'Popping item off stack: ${s.Pop}'
    /echo 'Popping item off stack: ${s.Pop}'

    /echo 'Stack is Empty: ${s.IsEmpty}'
    /echo 'Ending Stack Test'
    
    /return

Notes

• Pop decreases Count by 1 unless IsEmpty is true.
• Push increases Count by 1. IsEmpty will never be true after calling Push.
• Peek retrieves the last element Pushed onto the stack. Count is not modified by calling Peek.

See also

• stack

• Data Types