Address Operation - Substraction

Duration: 2 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 segment introduces pointer subtraction in C programming, specifically focusing on subtracting a constant from an address. The instructor explains that when a constant is subtracted from a pointer, the pointer moves backward by multiples of its data type's size. The syntax `ptr = ptr - n;` is presented as the standard method for this operation. A concrete example uses an integer array `int arr[5] = {10, 20, 30, 40, 50};` where a pointer `p` is initialized to the fourth element (`&arr[3]`). By executing `p = p - 1;`, the pointer moves back one integer size to point to `arr[2]`. Visual aids include hand-drawn memory diagrams and on-screen text calculations showing address changes, such as moving from address 1006 to 1004 assuming a 2-byte integer size.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The video begins by defining pointer subtraction rules, stating that subtracting a constant moves the pointer backward by `n * sizeof(data_type)`. On-screen text displays the syntax `ptr = ptr - n;` alongside an integer array example. The instructor sketches a hand-drawn memory diagram to visualize the array structure, showing elements 10 through 50. A pointer `p` is initialized to index 3 (`&arr[3]`). The operation `p = p - 1;` is demonstrated, resulting in the pointer moving from index 3 to index 2. The visual evidence confirms that the address changes based on the data type size, with text explicitly noting `p now points to arr[2], i.e., address of 30`.

  2. 2:00 – 2:19 02:00-02:19

    In the final segment, the lesson concludes with a specific numerical calculation of pointer arithmetic. The instructor shows that subtracting 1 from the pointer `p` (initialized at address 1006) results in a new address of 1004. This calculation is derived from the formula `1006 - 1 * 2 = 1004`, explicitly assuming a 2-byte integer size. The on-screen text reiterates the rule that pointers move backward by multiples of their data type's size. The visual diagram reinforces this by showing the pointer shifting from index 3 back to index 2, confirming that `p` now points to the address of value 30.

The lecture effectively demonstrates pointer subtraction by combining syntax rules with visual memory diagrams. The core concept is that `ptr - n` moves the pointer backward by `n * sizeof(type)`. The example of decrementing an integer pointer from index 3 to 2 serves as a practical application, showing how address arithmetic works in memory. The calculation `1006 - 2 = 1004` provides a concrete numerical verification of the theoretical rule. This progression from abstract syntax to specific memory addresses ensures students understand both the code and the underlying hardware behavior.

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