External Storage Class

Duration: 3 min

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Module outline

  1. Numerical Ability & Problem Solving: Speed Mathematics and Basic Mathematics, Arithmetic, Number System, HCF LCM, Divisibility Rules, Percentage, Ratio and Proportion (Ratios), Average, Profit and Loss, Simple Interest and Compound Interest, Mixture and Alligation, Time and Work, Pipe and Cistern, Speed Time and Distance, Age Problems, Partnership, Data Interpretation, Mental Ability, Sequence and Series (Series), Powers and Exponents (Surds and Indices), Algebra, Statistics, Logarithm, Mensuration and Geometry, Permutation and Combination, Probability, Sequences and Series, Powers, Surds and Logarithms, Subject-Verb Agreement, Sentence Completion, Geometry, Sentence Structure and Correction, Data Sufficiency, Trigonometry, Measurement and Quantity Take-Off, Signal Space and Optimum Detection, Probability, Statistics, Algebra, Time and Work, Speed, Time and Distance, Data Interpretation, Combinatorics
  2. Logical Reasoning: Series (Number and Letter Series) (Numerical Relations and Reasoning), Coding Decoding, Data Sufficiency, Syllogisms, Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning), Seating Arrangements, Blood Relations, Directions (Direction Test), Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning), Analytical Reasoning (Counting Figures Reasoning), Puzzle Solving (Puzzles), Calendar, Clock, Cubes & Dices, Logical Sequence Of Words, Venn Diagram, Data Arrangement, Inequality, Analogy, Ranking, Order and Sequence, Selection Decision Table (Decision Making), Alphabet and Word Tests, Numerical Reasoning, Number System, Averages, Mixtures and Alligation, Percentages, Series Completion, Analogy and Classification, Patterns in Two-Dimensional Figures, Coding and Decoding, Mathematical Operations, Direction Sense, Logical Deduction and Induction, Syllogisms and Venn Diagrams, Critical Reasoning, Order, Ranking and Sequence, Reading Comprehension, Profit, Loss and Discount, Constraint Puzzles, Traverse Surveying, Ratio and Proportion, Mensuration, Permutations and Combinations, Clocks and Calendars, Assembling and Grouping of Shapes, Transformation of Shapes, Three-Dimensional Patterns and Visualization, Cubes and Dice, Vocabulary, Blood Relations
  3. General Knowledge & Current Affairs (India + Rajasthan): History, Geography, Polity, Indian Economy, Static General Knowledge, State Wise GK, GK- Current Affairs, Environment, Physics
  4. Computer Fundamentals & Operating Systems: Basics of COA, Floating Point Rep, Digital Systems & Boolean Basics, Number Representation, Number System, Introduction to OS, File Management, Windows OS, Unix OS, Linux OS, Register Transfer and Microoperations, Virtual Memory
  5. Computer Networks: Introduction to CN, Data Communication, DLL: Error Control, DLL: Access Control, Data Link Layer - Ethernet, Net Layer: IPv4 & Proto, Application Layer, Hardware Basics, Network Security
  6. Cyber Security: Cyber Threats and Malware Attacks, Role of Internet and Web Services, Security in Mobile and Wireless Computing, Electronic Data Interchange and E-Commerce, Physical Security and Cryptography Basics, Intrusion Detection Systems (IDS), Cyber Safety and Security, Ethical Hacking
  7. Programming (C & OOP): C Fundamentals, Control Flow, Arrays & Pointers, Functions, Storage Classes, Structures & Enums, DMA, Macros, Scoping & File Handling, OOPS with C++, Operators & Expressions, Sorting Algorithms, Java Fundamentals, Java
  8. MS Office & Data Processing: MS Office Applications, Basics of DBMS
  9. Internet & Web Technology: Society, Law & Ethics, Terms & Abbreviations, Keyboard Shortcuts, Emerging Tech Trends, Artificial Intelligence, Emerging Technologies, Internet Fundamentals, Website, Browser & Services, Web Design & Development, Protocols & Services, Web Publishing & Hosting, Server Side & Security
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

This lecture introduces the external storage class in C programming, detailing its characteristics through a structured table and practical code examples. The instructor explains that external variables have a default initial value of zero, global scope, and a lifetime extending throughout the entire program execution. A C code snippet demonstrates how an external variable `i` is shared between the main function and helper functions like increment() and decrement(), illustrating that modifications in one function affect others due to global visibility. The lesson further clarifies scope conflicts where local variables take precedence over globals and introduces static variables declared outside functions, which share external behavior but are file-scoped. Finally, the video concludes by discussing the rationale behind C's storage classes, emphasizing that programmers should choose them to economize memory space and improve execution speed.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The lecture begins by defining the external storage class using a table that lists three key features: default initial value, scope, and life. On-screen text explicitly states the default initial value is Zero, the scope is Global, and the life lasts as long as program execution continues. The instructor uses red underlines to emphasize 'Global' and a checkmark next to 'Zero'. A C code example is then introduced showing an external variable `int i = 1;` declared outside the main function. This code demonstrates how functions like increment() and decrement() access this shared variable, proving that external variables maintain state across function calls.

  2. 2:00 – 2:56 02:00-02:56

    The instructor transitions to discussing variable scope conflicts, explaining that if a local and global variable share the same name, the local variable takes precedence. The slide shows code where `printf` accesses a variable defined in two places, highlighting this shadowing behavior. The lesson then introduces static variables declared outside functions, noting they act like external variables but are limited in scope to the file where defined. The segment concludes with a slide titled 'Which to Use When', which states that Dennis Ritchie provided storage classes so programmers could decide based on two goals: to economize memory space and improve the speed of execution.

The video provides a foundational overview of C storage classes, specifically focusing on the external class. It establishes that external variables are initialized to zero by default and possess global scope, meaning they are accessible from any function within the program. The practical demonstration using `int i = 1;` outside main() effectively shows how this scope allows multiple functions to modify and access the same memory location. The lecture also touches on related concepts like static variables, which offer file-level scope similar to external variables but with different linkage properties. The final section contextualizes these technical details within the broader design philosophy of C, where storage classes are tools for memory optimization and performance tuning rather than rigid rules.

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