stack<datatype> creates a new stack that is empty. It needs no parameters and returns an empty stack. It can only contain a certain type of data. e.g. int, string etc.
push(item) adds a new item to the top of the stack. It needs the item and returns nothing.
pop() removes the top item from the stack. It needs no parameters and returns nothing. The stack is modified.
top() returns the top item from the stack but does not remove it. It needs no parameters. The stack is not modified.
empty() tests to see whether the stack is empty. It needs no parameters and returns a Boolean value.
size() returns the number of items on the stack. It needs no parameters and returns an integer.
s is a stack that has been created and starts out empty, then Table 3.4.1 shows the results of a sequence of stack operations. Under stack contents, the top item is listed at the far right.
| Stack Operation | Stack Contents | Return Value |
|---|---|---|
s.empty() |
[] |
1 |
s.push('horse') |
['horse'] |
|
s.push('dog') |
['horse','dog'] |
|
s.top() |
['horse','dog'] |
'dog' |
s.push('cat') |
['horse','dog','cat'] |
|
s.size() |
['horse','dog','cat'] |
3 |
s.empty() |
['horse','dog','cat'] |
0 |
s.push('turtle') |
['horse','dog','cat','turtle'] |
|
s.pop() |
['horse','dog','cat'] |
|
s.pop() |
['horse','dog'] |
|
s.size() |
['horse','dog'] |
2 |
