TLDR;
This module introduces the concept of data structures in C++ and how they are available as part of the C++ standard library. It uses the stack data structure as an example to illustrate the differences between implementing a stack in C and using the stack provided by the C++ standard library. The module also provides an overview of other common data structures available in C++ and categorizes them into containers and container adapters.
- C++ standard library provides readymade data structures as containers.
- Containers work like data types, allowing for elements of varied types, including user-defined types.
- C++ offers container adapters, which are adaptations of existing containers with specific interfaces.
Introduction to Data Structures in C++ [0:26]
The lecture introduces the concept of data structures in C++ and their importance in problem-solving, closely related to algorithms. It mentions that the module will explore common data structures available in the C++ standard library, using stack as an example to compare user-written C stacks with those provided by C++. The lecture outlines the topics to be covered, starting with stacks in C.
Stack Implementation in C [1:55]
The lecture reviews the concept of a stack as a container that follows the Last In First Out (LIFO) principle. Creating a stack involves deciding on the data type of elements, defining a container structure, and setting a maximum size. The implementation requires declaring a 'top' variable to mark the topmost element. The functionality is defined by four operations: push (adding an element), pop (removing an element), top (checking the topmost element), and is-empty (checking if the stack is empty). In C, changing the data type of the element requires re-implementing the stack, as the C standard library does not provide a readymade stack due to the need for different implementations for different data types.
Applications of Stack Data Structure [5:39]
The lecture emphasizes the importance of stacks as a data structure for solving various problems. Examples include reversing a string by pushing elements onto the stack and then popping them off, and evaluating postfix expressions. The process involves scanning the expression, pushing values onto the stack, and performing operations when encountering operators. Stacks can also be used to identify palindromes, convert infix to postfix notations and implement depth-first search algorithms.
Writing Stack in C [9:30]
The lecture explains how to write a stack in C, using an array as a container and an array index variable 'top' as a marker. The stack functions are global, requiring the stack to be passed as a parameter to each function. The functions include push, pop, top, and is-empty. The stack needs to be declared and initialized with a value for the marker indicating it is empty. Examples of using the stack include reversing a string and postfix evaluation.
Stack Implementation in C++ [14:01]
The lecture transitions to C++, where the standard library provides a stack header, allowing for stacks of any type using templates. The C++ code is compared to C code, highlighting that C++ requires including the stack header and using templates to define the data type of the stack. This eliminates the need for separate initialization and provides a cleaner interface. The advantage of using data structures as part of the library is that it reduces the amount of code needed and minimizes errors.
Containers in C++ Standard Library [17:50]
The lecture explains that in C++, data structures are referred to as containers because they hold a collection of data with specific operations. The C++ standard library provides several readymade containers that work like data types, allowing elements of varied types, including user-defined types. These containers are implemented using class templates and manage storage space while providing functions to access the data. They also support iterators, which are generalized for loops.
Container Adapters [22:27]
The lecture introduces container adapters, which are containers adapted to behave differently with a different set of functions. Examples include implementing a stack using an array, where the array is the basic container, but the stack interface provides push, pop, is-empty, and top functions. Other examples include queues and priority queues. Container adapters use an underlying container and provide a specific interface relying on the object of one of the container classes.
Overview of Data Structures in C++ Standard Library [24:56]
The lecture provides an overview of the data structures available in the C++ standard library, including vectors, lists, deques, stacks, queues, and priority queues. It categorizes them into sequential containers and associative containers. Associative containers, such as sets and maps, are used when the value of the element is important for storage and retrieval. Sets are collections of unique elements with no specific order, while maps are name-value pairs with unique keys. The underlying structure for sets and maps is a binary search tree.