← VCE Software Development U3O1

Plain text (TXT) files: structure

A plain text file holds unformatted characters, usually one line of text per line ended by a newline. It has no field headings or data types, so everything is read as a string.

Part of: VCE Software Development - U3O1 - Programming — Module 103, VCE Software Development - U4O1 - development and evaluation — Module 48, QCE Digital Solutions Unit 2 — Data-Driven Problems and Solution Requirements — Module 9, QCE Digital Solutions Unit 3 — Real-World Problems and Solution Requirements — Module 36, QCE Digital Solutions Unit 3 — Innovative Digital Solutions — Module 44, QCE Digital Solutions Unit 4 — Prototype Digital Data Exchanges — Module 77, WA Computer Science ATAR Year 11 — Data Management — Module 13

Understanding Plain text (TXT) files: structure in VCE Software Development U3O1

What it does: Nothing in the file says that the lines are names and marks. The program must know the layout itself. int() converts the string read from the file into an integer. A TXT file stores no data types. Lines in a TXT file end with a newline character (\n). Closing tags belong to XML. line is a string, so line + 5 causes a type mismatch error. Convert it with int() first. A .txt file is plain text. XML files use tags to give the data structure. A TXT file usually stores one item of text per line, and each line is ended by a newline.

Common mistakes: Everything read from a text file is a string, so line + 5 mixes a string and an integer and causes a TypeError. Convert it first: total = int(line) + 5. readlines needs brackets to be called. Without them names holds the method itself, not the list of lines. It should be names = f.readlines().

Class: _____________________ · Name: _____________________ · Date: _________

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This module's key terms are also in a printable crossword (Modules 98–113) and word search (Modules 72–113).

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Learning

Duo

Which statement best describes a plain text (TXT) file?

It stores unformatted characters, usually one item per lineIt stores numbers, dates and strings as separate typed fields

Matches

total = file.readline() + 10

↓

The line read from a TXT file is a string, so adding the integer 10 causes a type error. Convert it with int() first.

Applying

Meanings

Term

TXT file

Meaning

A plain text file holds unformatted characters, usually one line of text per line ended by a newline. It has no field headings or data types, so everything is read as a string.

Practice

Ava Nguyen

Testing

Gaps

f.write("Ava")

Check Answer

Spots

2line = f.readline()

3total = line + 5

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Quick Questions

1. Which statement best describes a plain text (TXT) file?

A. It stores unformatted characters, usually one item per line ✓

B. It stores numbers, dates and strings as separate typed fields

A TXT file is just characters. It has no built-in fields or data types.

2. How does a TXT file usually mark the end of each line of text?

A. A closing tag such as </line>

B. A newline character ✓

Lines in a TXT file end with a newline character (\n). Closing tags belong to XML.

3. A TXT file contains the line 42. In Python, what type is the value after reading it with readline()?

A. An integer

B. A string ✓

Everything read from a TXT file is a string. You must convert it with int() if you need a number.

4. Which is true about field headings in a plain TXT file?

A. There are no built-in field headings ✓

B. The first line is always treated as the field headings

A TXT file has no structure for headings. Any heading is just another line of text that your program must handle.

5. A program reads the line 15 from scores.txt and needs to add 5 to it. Which code is correct?

A. total = int(line) + 5 ✓

B. total = line + 5

line is a string, so line + 5 causes a type mismatch error. Convert it with int() first.

Match the Pairs

Ava\nLiam\nMia → A TXT file where each line holds one item, and the end of each line is marked by a newline character

line = file.readline() # reads 88 → The value read from a TXT file is the string '88', not the integer 88

A TXT file has no field headings, so the file does not label what each line means → Ava\n88\nLiam\n65

Because everything in a TXT file is read as a string, a number must be converted before it is used in a calculation → mark = int(file.readline())

total = file.readline() + 10 → The line read from a TXT file is a string, so adding the integer 10 causes a type error. Convert it with int() first.

Name: Ava, Mark: 88 stored in a TXT file as typed fields → A TXT file has no fields or data types, so it cannot store typed fields with headings. It only holds plain characters, usually one line per item.

Key Term

TXT file

A plain text file holds unformatted characters, usually one line of text per line ended by a newline. It has no field headings or data types, so everything is read as a string.

Fill in the Blanks

1. f = open("names.txt", "w") f.write("Ava\n")

Hint: Type the escape sequence that ends a line of text in the file.

2. line = f.readline() age = int(line)

Hint: Type the function that converts the text read from the file into a whole number.

3. f = open("names.txt") lines = f.readlines()

Hint: Type the file method that returns every line of the file as a list.

4. line = f.readline() name = line.strip()

Hint: Type the string method that removes the newline character from the end of a line.

5. line = f.readline() print(type(line) == str)

Hint: Type the data type that every value read from a text file has.

Spot the Error

Question 1

A f = open("scores.txt")

B line = f.readline()

C total = line + 5

D print(total)

E f.close()

Line C — Everything read from a text file is a string, so line + 5 mixes a string and an integer and causes a TypeError. Convert it first: total = int(line) + 5.

Question 2

A f = open("names.txt", "r")

B names = f.readlines

C print(len(names))

D f.close()

Line B — readlines needs brackets to be called. Without them names holds the method itself, not the list of lines. It should be names = f.readlines().

Question 3

A with open("notes.txt") as f

B text = f.read()

C print(text)

Line A — A with statement must end with a colon so the indented block below it belongs to it. It should be with open("notes.txt") as f:

Question 4

A f = open("log.txt", "w")

B f.write("Login ok/n")

C f.write("Logout\n")

D f.close()

Line B — A newline character is written \n with a backslash, not /n. With /n the text ends in the characters /n instead of ending the line. It should be f.write("Login ok\n").

Question 5

A f = open("names.txt")

B for line in f:

C name = line.trim()

D print("Hi " + name)

Line C — Python strings have no trim() method. Use strip() to remove the newline at the end of each line. It should be name = line.strip().

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