CS201 Midterm Important Key Points Updated

MIDTERM (SHORT NOTES) · 2024 - 2025 · CS201 Important Key points

Lecture 1 – What Is Programming?

A program is a precise sequence of steps to solve a problem. Programming builds critical reading, analytical thinking, and creative synthesis. Essential skills: attention to detail, commenting, designing for reusability & UI, understanding that computers follow instructions literally. Follow a design recipe: analyze the problem, abstract with examples, write precise specs, test and refine.

Lecture 2 – Software & Development Environment

Software categories: system (OS, drivers, utilities) vs. application software. History of C: evolved from BCPL and B, standardized by ANSI/ISO in 1989. Development tools: text editor →preprocessor →compiler →linker →loader → debugger. Utilities: compression, defragmentation—manage disk performance.

Lecture 3 – First C Programs & Basics

Structure: #include <iostream.h>, main(), { }, statements ending in ;. I/O streams: cout << for output, cin >> for input. Variables & data types: int, short, long, float, double, char. Assignment = vs. comparison ==; arithmetic operators + – * / %; operator precedence and use of parentheses.

Lecture 4 – Expressions & Sample Programs

Build programs step by step: declare variables, prompt input, compute, display. Integer division truncates decimals; use floats for real‐number results. Use clear prompts (cout) and cin for robust user interaction. Practice writing and tracing expressions, enforce evaluation order with parentheses.

Lecture 5 – Decision Making (if)

if (condition) executes its block when true; braces {} group multiple statements. Relational operators: > < >= <= == !=. Logical operators introduced later; use flowcharts (diamond symbol) to design decision logic.

Lecture 6 – if/else & Logical Operators

Extend decisions with else and else if for two‐way or multi‐way branching. Logical operators: AND &&, OR ||, NOT !; combine multiple conditions. Beware using single = instead of == in conditions—leads to logical bugs.

Lecture 7 – for Loops

for (init; condition; update) is ideal when the iteration count is known. Order: initialization →test →body →update →repeat. Common pattern: for (int i = 0; i < N; i++) { … }.

Lecture 8 – while & do-while Loops

while (cond) checks before entry; may execute zero times. do { … } while (cond); checks after body—executes at least once. Use break to exit loops early, continue to skip to the next iteration.

Lecture 9 – Functions & Modular Design

Divide code into reusable functions: declaration (signature) vs. definition (body). All programs start with main(), which may call other functions. Top‐down design: break complex tasks into subtasks, implement and test each.

Lecture 10 – Header Files & Scope

#include pulls in declarations (e.g., <iostream.h>). Scopes: global (file scope), function‐level, block‐level—minimize globals. Parameter passing: default is call by value (copies), optional call by reference (addresses).

Lecture 11 – Arrays & Linear Search

Arrays: contiguous memory, zero‐based indexing. Declaration: int a[10];; initialization: = {0} or loop‐based. Copy arrays via loops; search linearly with for (i = 0; i < n; i++) if(a[i]==key) …. Use const to protect arrays from modification.