NEB Class 12 • Computer Science • Programming II • Concept Guide

Structures & Unions in C: NEB Class 12 Computer Guide

Master Structures and Unions in C through clear concepts, representations, a reliable answer method and exam-focused practice.

ConceptsWorked reasoningNEB practice

Core concept

What Structures and Unions in C means physically

A structure groups named members that occupy separate storage within one object; union members share the same storage and only the currently valid representation should be read under the program’s rules.

Use . for an object member and -> through a pointer. sizeof may include padding; union size accommodates its largest member plus alignment.

The institutional reference gives the wider physical model; the CDC curriculum determines the NEB boundary.

Worked checkpoint with interpretation

struct Student{int id;char name[40];}; creates records with both fields, while a tagged union pairs a type tag with one active alternative.

Do not stop at the number. State what the sign, ratio, spacing, frequency or direction means. A common error is Treating struct members as parallel arrays, using -> on a non-pointer, assuming no padding, or reading a union member that is not the active representation.

NEB answer method

Model → evidence → equation → check

First identify the system and what the question asks. Label the diagram, apparatus or reaction with SI quantities, then state the principle before selecting an equation. Solve symbolically where possible and check units, limiting cases and chemical or physical meaning.

Stage	Question	Evidence
Model	What is idealised?	Assumption stated
Representation	Which diagram fits?	Labels or balanced equation
Calculation	Which relation follows?	Symbols then SI values
Evaluation	Does it make sense?	Unit, sign and trend check

Make the idea concrete in Nepal

Connect the model to a school laboratory, household technology, health, environment, energy or local material. The example should clarify the science rather than merely mention a place. Compare a prediction with an observation and record uncertainty.

Review the NEB Class 12 Computer Science revision roadmap and the complete Computer Science guide. For online or physical tuition, call 9846662070.

Frequently asked questions

Questions students ask about Structures and Unions in C

What is the central idea of Structures and Unions in C?+

Which equation should I remember?+

Use . for an object member and -> through a pointer. sizeof may include padding; union size accommodates its largest member plus alignment.

How should I begin a numerical?+

Draw the situation, list known quantities in SI units, choose the governing relation symbolically, substitute once and finish with a unit and reasonableness check.

What is a common exam mistake?+

Treating struct members as parallel arrays, using -> on a non-pointer, assuming no padding, or reading a union member that is not the active representation.

How can I practise this topic?+

Alternate one concept explanation, one diagram and two numericals. Revisit errors after a day instead of only rereading the solution.

Where can I get tuition support?+

For online or physical KTM Tuition classes, call 9846662070. After Grade 12, the MKS Education panel below gives preparation and pre-counselling contacts.

References and next steps

Scope checked against CDC Nepal; concept support from an institutional reference and OpenStax Science. Continue with the Structures and Unions in C cluster.

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