SizeOf Operator

Duration: 8 min

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Module outline

  1. General Intelligence & Reasoning: Analogy, Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning), Series (Number and Letter Series) (Numerical Relations and Reasoning), Coding Decoding, Blood Relations, Directions (Direction Test), Ranking, Order and Sequence, Logical Sequence Of Words, Syllogisms, Venn Diagram, Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning), Selection Decision Table (Decision Making), Data Sufficiency, Puzzle Solving (Puzzles), Data Arrangement, Cubes & Dices, Calendar, Clock, Arithmetic, Number System, HCF LCM, Verbal Analogy (Word Based Analogy), Visual Recognition and Figure Completion, Paper Folding and Cutting, Transformation of Shapes, Clocks and Calendars, Direction Sense, Cubes and Dice, Patterns in Two-Dimensional Figures, Seating Arrangements, Analogy and Classification, Logical Deduction and Induction, Alphabet and Word Tests, Mathematical Operations, Series Completion, Simplification and Approximation, Coding and Decoding, Numerical Reasoning, Assembling and Grouping of Shapes, Three-Dimensional Patterns and Visualization, Vocabulary, Number System, Averages, Mixtures and Alligation, Simple and Compound Interest, Percentages, Algebra, Speed, Time and Distance, Seating and Arrangement Puzzles, Traverse Surveying, Order, Ranking and Sequence, Constraint Puzzles, Syllogisms and Venn Diagrams, Reading Comprehension, Critical Reasoning, Permutations and Combinations, Narrative Sequencing, Project Monitoring, Resources and Safety, Profit, Loss and Discount, Ratio and Proportion, Time and Work, Mensuration, Data Interpretation, Powers, Surds and Logarithms, Sequences and Series, Articles and Determiners, Sentence Completion, Data Sufficiency, Blood Relations, Simple Interest and Compound Interest, Mixture and Alligation, Sequence and Series (Series), Speed Time and Distance, Algebra, Profit and Loss, Powers and Exponents (Surds and Indices), Permutation and Combination
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  5. Computer Organisation & Architecture: Basics of COA, Cache Memory Organization, Input Output Organisation, Pipelining, Instr Formats & Modes, Control Unit Design, Programming the Basic Computer, Register Transfer and Microoperations, Semiconductor Memories and Programmable Logic, Processor Organization and Instructions, Memory Hierarchy and Input/Output, Registers and Counters
  6. Programming & Data Structures: C Fundamentals, Control Flow, Functions, Arrays & Pointers, Storage Classes, Structures & Enums, DMA, Macros, Scoping & File Handling, Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing, HTML Basics, OOPS with C++, Java, Object Oriented Technology
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  8. Algorithms: Algorithm Analysis, Time Complexity Analysis, Sorting Algorithms, Greedy Algorithms, Dynamic Programming, Minimum Spanning Trees, Shortest Path Algos
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  13. Full Length Mock Tests:
  14. Sectional Tests:
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

This lecture introduces the sizeof() operator in C, defining it as a compile-time mechanism that determines the size of data types or variables in bytes. A central teaching point is that expressions within sizeof() are not executed, meaning side effects like assignments do not occur. The instructor uses specific code examples to demonstrate that while sizeof() returns the size of an integer (e.g., 2 bytes on a 16-bit machine), variables modified inside the operator remain unchanged. The syntax allows sizeof to be applied to variables, types, values, or expressions.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The video begins by defining the sizeof() operator as a tool to find the size in bytes of a datatype, variable, or expression. The slide explicitly states it is the only operator evaluated at compile time. A key rule highlighted with red circles and underlining is that expressions inside sizeof are not executed. The instructor presents the syntax sizeof (variable | type | value | expression) and uses a code example where int x = sizeof(a = 10); is shown. The output explanation clarifies that while x stores the size of an integer (2 bytes), the variable a remains 5 because the assignment inside sizeof is ignored.

  2. 2:00 – 5:00 02:00-05:00

    The final segment revisits the core concept that sizeof() is evaluated at compile time and expressions are not executed. The instructor uses printf statements to show the output of a variable that was never modified inside sizeof(). The slide displays int x = sizeof(a > 10); to show that even relational expressions are not evaluated for their truth value but only for the size of the result type. The output remains consistent: a is 5, and x holds the integer size (2 bytes). This reinforces that sizeof() operates on types rather than runtime values.

  3. 5:00 – 8:29 05:00-08:29

    The lecture continues to reinforce the non-execution rule of expressions within sizeof(). The instructor emphasizes that side effects, such as assignments or increments, do not happen inside the operator. A code snippet demonstrates int a = 5; followed by sizeof(a = 10), where the output confirms a is still 5. The slide notes that sizeof returns the size of an integer, which varies by architecture (e.g., 2 bytes on a 16-bit machine). Handwritten annotations show arithmetic like 10 + 3 to illustrate that sizeof evaluates the type size, not the expression result.

The lecture establishes that sizeof() is a compile-time operator unique for not executing its operand expressions. This prevents side effects, ensuring variables retain their original values even if modified inside sizeof(). The operator returns the byte size of a type, which depends on the machine architecture (e.g., 2 bytes for int on 16-bit systems). Examples consistently show that assignments like a = 10 inside sizeof(a = 10) are ignored, and the variable remains unchanged. The syntax supports variables, types, values, or expressions, but only the type size is returned.

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