What is Array Stack?

Contents

• What is Stack and How it works?
• Structure of Array Stack
  • Advantage of Array List
  • Disadvantage of Array List
• Operations for Array Stack
  • Push
  • Pop
  • Peek
  • Implementation

What is Stack and How it works?

• Stack is a sequential structure that store data linearly.
• The order is LIFO(Last-In, First-Out).
• Adding and removing data is done in the top of the stack.
• Stack can be thought of as a vertical structure.

Structure of Array Stack

• Array Stack is implemented using array.
• Array Stack has top.
  • The insertion and deletion of data occurs in the top.

Advantage of Array List

• It takes O(1) to get the element in the array.

Disadvantage of Array List

• The size of the array is fixed, so you cannot insert more elements than the size of the array.
  • Resize is required when larger size array is needed.
• The empty space cannot be filled when the front moves ahead.

Operations for Array Stack

• Calculate the top using the variable curretCount.

Push

• The new data is inserted into the location of top + 1.
  • The location index of the top can be found by the variable currentCount.
  • CurrentCount is a variable that means the current number of nodes.
  • Top = currentCount - 1
• Therefore, the location index where the new data will be inserted is the currentCount.
• If currentCount is equal to maxCount, the stack is full.
• After inserting the data, increase the number of nodes by 1.
  • currentCount++;

// Insert new data into the top.
pStack->pData[pStack->currentCount].data = data;
// Increase the variable currentCount indicating the current number of nodes.
pStack->currentCount++;

Pop

• Remove the node on the Top.
  • The location of the top is currentCount - 1.
• After removing the node in the top, reduce the number of nodes by 1.
  • currentCount–;

// Set the node to return.
pReturn->pData = pStack->pData[pStack->currentCount - 1]
// Decrease the variable currentCount indicating the current number of nodes.
pStack->currentCount--;

Peek

• Peek only returns the node in the top without removing it.
• Returns the node located in the Top.
  • Top = curretCount-1.

pReturn = &(pStack->pData[queue->currentCount - 1]);

Implementation

GitHub