Are these Basic Input Output and File Handling notes free?

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Is this for Class 11 ISC Computer Science?

Yes, it is written for the ISC Computer Science syllabus.

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Basic Input Output and File Handling — Class 11 ISC Computer Science revision notes

Q: What does the Basic Input Output and File Handling revision sheet cover?

Reading input with Scanner, The nextInt then nextLine trap, Fixing the nextInt then nextLine gap, A file's life in a program, in order, open, read or write, repeat, close, print, println and printf, print, println, printf.

A 3-page visual revision sheet for Basic Input Output and File Handling, written for Class 11 ISC Computer Science. Formulas, diagrams and the traps that cost marks, laid out to be read the night before rather than the term before. Free, and it opens inside CapCompass.

Basic Input Output and File Handling revision notes, page 1 of 3 — A preview of page 1 — all 3 pages open full size in the app.

Basic Input Output and File Handling in one look

reading the keyboard, printing back, and keeping the result after the program ends

Reading input with Scanner

import java.util.Scanner; brings the class in, and Scanner input = new Scanner(System.in); opens a channel to the keyboard
input.nextInt() reads one int, input.nextDouble() reads one double, input.next() reads one word up to the next space
input.nextLine() reads an entire line, including spaces, up to where Enter was pressed
each next call waits for input before the next statement runs, so print a prompt with System.out.print before every read

The nextInt then nextLine trap

the previous read on this Scanner was

nextInt() or nextDouble() — the Enter key press is still waiting unread: a nextLine() straight after reads an empty line
nextLine() already — the line is fully consumed: the next nextLine() reads cleanly
next() — the Enter key press is still waiting unread: the same fix as after nextInt() is needed

Fixing the nextInt then nextLine gap

nextInt() reads only the digits, and leaves the Enter key press sitting unread in the input
a nextLine() called straight after nextInt() reads that leftover Enter and returns an empty String, not the line the user meant to type
an extra input.nextLine(); with its result thrown away, placed right after the nextInt(), clears that leftover Enter
this exact ordering is one of the most reliable questions asked on Scanner, since it looks correct and still returns the wrong value

A file's life in a program, in order

open
read or write
repeat
close

Page 1 of 3. The full sheet, all 3 pages, opens free in the app.

What this Basic Input Output and File Handling sheet covers

Reading input with Scanner
The nextInt then nextLine trap
Fixing the nextInt then nextLine gap
A file's life in a program, in order
open
read or write
repeat
close
print, println and printf
print
println
printf
Formatting numeric output with printf
Tracing a Scanner read order
Writing to a text file
Reading a text file back
Traps that cost marks
Tricks that save time

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