Rust-Programming-Language/C2/File-Handling/English - Revision history

Madhurig at 13:29, 18 December 2025

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Madhurig at 13:21, 18 December 2025

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Madhurig at 12:25, 4 December 2025

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Madhurig at 05:40, 13 November 2025

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Nirmala Venkat: Created page with "{| border="1" |- || '''Visual Cue''' || '''Narration''' |- || '''Slide 1''' || Welcome to the Spoken Tutorial on
2025-10-28T08:56:45Z

Created page with "{| border="1" |- || '''Visual Cue''' || '''Narration''' |- || '''Slide 1''' || <span style="color:#000000;">Welcome to the Spoken Tutorial on </span><span style="color:#000000..."

New page
{| border="1"
|-
|| '''Visual Cue'''
|| '''Narration'''
|-
|| '''Slide 1'''
|| <span style="color:#000000;">Welcome to the Spoken Tutorial on </span><span style="color:#000000;">'''File Handling '''</span><span style="color:#000000;">in </span><span style="color:#000000;">'''Rust.'''</span>
|- style="border:1pt solid #000000;padding-top:0cm;padding-bottom:0cm;padding-left:0.206cm;padding-right:0.191cm;"
|| <div style="color:#000000;">'''Slide 2'''</div>

<div style="color:#000000;">'''Learning Objectives'''</div>
|| In this tutorial, we will learn about:
* <div style="color:#000000;margin-left:1.27cm;margin-right:0cm;">File operations</div>
* <div style="margin-left:1.27cm;margin-right:0cm;"><span style="color:#000000;">Input and </span>Output<span style="color:#000000;"> operations</span></div>

|- style="border:1pt solid #000000;padding-top:0cm;padding-bottom:0cm;padding-left:0.101cm;padding-right:0.191cm;"
|| <div style="color:#000000;">'''Slide 3'''</div>

<div style="color:#000000;">'''System Requirements'''</div>
|| <div style="color:#000000;">To record this tutorial I’m using the following setup.</div>

|- style="border:1pt solid #000000;padding-top:0cm;padding-bottom:0cm;padding-left:0.101cm;padding-right:0.191cm;"
|| <span style="color:#000000;">'''Slide'''</span><span style="color:#000000;"> </span><span style="color:#000000;">'''5'''</span>

<div style="color:#000000;">'''Code Files'''</div>
||
* <div style="color:#000000;">The following code file is required to practise this tutorial.</div>
* <div style="color:#000000;">This file is provided in the Code Files link of this tutorial page.</div>

|- style="border:1pt solid #000000;padding-top:0cm;padding-bottom:0cm;padding-left:0.101cm;padding-right:0.191cm;"
|| <span style="color:#000000;">'''Slide</span> 6'''

<div style="color:#000000;">'''File I/O – Standard Library'''</div>

<div style="color:#001d35;"></div>

|| <span style="color:#000000;">'''File Input/Output'''</span><span style="color:#000000;"> operations are done </span>using <span style="color:#000000;">the below modules from the Standard Library </span>
* <div style="color:#000000;margin-left:1.27cm;margin-right:0cm;">'''std::fs '''is a module for file handling </div>
* <div style="margin-left:1.27cm;margin-right:0cm;"><span style="color:#000000;">'''std::io '''</span><span style="color:#000000;">is a module for reading and writing </span></div>

|- style="border:1pt solid #000000;padding-top:0cm;padding-bottom:0cm;padding-left:0.206cm;padding-right:0.191cm;"
|| <span style="color:#000000;">Open </span><span style="color:#000000;">'''Visual'''</span><span style="color:#000000;"> </span><span style="color:#000000;">'''code editor'''</span>
|| Open the '''Visual Studio code editor.'''
|- style="border:1pt solid #000000;padding-top:0cm;padding-bottom:0cm;padding-left:0.206cm;padding-right:0.191cm;"
| style="color:#000000;" |
|| I have created the '''filehandling''' project as explained earlier.
|- style="border:1pt solid #000000;padding-top:0cm;padding-bottom:0cm;padding-left:0.206cm;padding-right:0.191cm;"
|| <span style="color:#000000;">Point to the </span><span style="color:#000000;">'''main.rs'''</span><span style="color:#000000;"> file.</span>

|| <span style="background-color:#ffffff;color:#000000;">In the </span><span style="background-color:#ffffff;color:#000000;">'''main.rs '''</span><span style="background-color:#ffffff;color:#000000;">file, copy and paste the code from the Code file.</span>
|- style="border:1pt solid #000000;padding-top:0cm;padding-bottom:0cm;padding-left:0.206cm;padding-right:0.191cm;"
|| <div style="color:#000000;">use std::fs::File;</div>

<div style="color:#000000;">use std::io::{self, Write};</div>

<div style="color:#000000;">fn main() -> io::Result<()> {</div>

<div style="color:#000000;">let mut file = File::create("output.txt")?; // Create or overwrites file</div>

<div style="color:#000000;">file.write_all(b"Hello, Rust file writing!")?; // Write bytes to file</div>

<div style="color:#000000;">println!("Data written to file");</div>

<div style="color:#000000;">Ok(())</div>

<div style="color:#000000;">}</div>
|| <span style="color:#000000;">We import the </span><span style="color:#000000;">'''File'''</span><span style="color:#000000;"> struct from the </span><span style="color:#000000;">'''std:fs'''</span><span style="color:#000000;"> module.</span>

<span style="color:#000000;">'''File'''</span><span style="color:#000000;"> is used t</span>o <span style="color:#000000;">creat</span>e<span style="color:#000000;">, </span>open<span style="color:#000000;"> and </span>work<span style="color:#000000;"> with files.</span>

<span style="color:#000000;">Then we import the </span><span style="color:#000000;">'''io'''</span><span style="color:#000000;"> module and </span><span style="color:#000000;">'''write'''</span><span style="color:#000000;"> the trait.</span>

<span style="color:#000000;">Here </span><span style="color:#000000;">'''self'''</span><span style="color:#000000;"> means </span>i<span style="color:#000000;">mporting</span><span style="color:#000000;">''' std::io '''</span><span style="color:#000000;">itself as</span><span style="color:#000000;">''' io.'''</span>

<span style="color:#000000;">In the main function,</span><span style="color:#188038;"> </span><span style="color:#000000;">'''File::create()'''</span><span style="color:#000000;"> method creates a new file called </span><span style="color:#000000;">'''output.txt.'''</span>

<div style="color:#000000;">If it already exists, it truncates it before writing. otherwise creates a new file.</div>

<span style="color:#000000;">'''Write_all '''</span><span style="color:#000000;">writes all the</span><span style="color:#000000;">''' bytes'''</span><span style="color:#000000;"> from the given byte string into the file.</span>

<span style="color:#000000;">The</span><span style="color:#000000;">''' b'''</span><span style="color:#000000;"> before the string literal means that we are writing </span><span style="color:#000000;">'''raw bytes'''</span><span style="color:#000000;">, not a </span><span style="color:#188038;">String</span><span style="color:#000000;">. </span>

<div style="color:#000000;">This is often safer and faster for low-level writing.</div>

<span style="color:#000000;">The </span><span style="color:#188038;">?</span><span style="color:#000000;"> operator is used to handle any write failure.</span>

<span style="color:#000000;">After successful writing, we </span>print<span style="color:#000000;"> a success</span><span style="color:#000000;">ful </span><span style="color:#000000;">message.</span>

W<span style="color:#000000;">e </span>return the '''Ok<span style="color:#000000;">()'''</span><span style="color:#000000;"> method variant to signal that everything worked without errors.</span>

<div style="color:#000000;">Save the file.</div>
|- style="border:1pt solid #000000;padding-top:0cm;padding-bottom:0cm;padding-left:0.206cm;padding-right:0.191cm;"
|| Open and show the file
|| <span style="color:#000000;">In the terminal</span>,<span style="color:#000000;"> type </span><span style="color:#000000;">'''cargo run '''</span><span style="color:#000000;">to see the output.</span>

Let us open the '''output.txt.''' We can see the data written to the file.
|- style="border:1pt solid #000000;padding-top:0cm;padding-bottom:0cm;padding-left:0.206cm;padding-right:0.191cm;"
| style="color:#252525;" |
| style="color:#000000;" | Next let us see how to read from a file.
|- style="border:1pt solid #000000;padding-top:0cm;padding-bottom:0cm;padding-left:0.206cm;padding-right:0.191cm;"
| style="color:#252525;" |
|| <span style="color:#252525;">Clear the code window and r</span><span style="color:#000000;">eplace the code from the code file as shown</span><span style="color:#252525;">.</span>
|- style="border:1pt solid #000000;padding-top:0cm;padding-bottom:0cm;padding-left:0.206cm;padding-right:0.191cm;"
|| <div style="color:#000000;">use std::fs::File;</div>

<div style="color:#000000;">use std::io::{self, Read};</div>

<div style="color:#000000;">fn main() -> io::Result<()> {</div>

<div style="color:#000000;">let mut file = File::open("output.txt")?; // Open file in read-only mode</div>

<div style="color:#000000;">let mut contents = String::new();</div>

<div style="color:#000000;">file.read_to_string(&mut contents)?; // Read file into a string</div>

<div style="color:#000000;">println!("File content: {}", contents);</div>

<div style="color:#000000;">Ok(())</div>

<div style="color:#000000;">}</div>
|| <span style="color:#000000;">We import t</span>he <span style="color:#000000;">'''Read trait '''</span><span style="color:#000000;">from the </span><span style="color:#000000;">'''io'''</span><span style="color:#000000;"> module.</span>

<span style="color:#000000;">In the main function, we return </span><span style="color:#188038;">io::Result<()></span><span style="color:#000000;">.</span>

<span style="color:#188038;">File::open()</span><span style="color:#000000;"> method opens</span><span style="color:#000000;">''' output.txt '''</span><span style="color:#000000;">file</span><span style="color:#000000;"> in </span><span style="color:#000000;">'''read-only'''</span><span style="color:#000000;"> mode.</span>

<div style="color:#000000;">? propagates an error if the file doesn’t exist or can’t be opened.</div>

<div style="color:#000000;">We create an empty String to hold the file’s contents.</div>

<span style="color:#000000;">Next we create a mutable String named </span><span style="color:#000000;">'''contents'''</span>.

It stores the <span style="color:#000000;">contents that are read</span>.

<div style="color:#000000;">Finally, we print the file contents to the console.</div>

<div style="color:#000000;">Save the program.</div>
|- style="border:1pt solid #000000;padding-top:0cm;padding-bottom:0cm;padding-left:0.206cm;padding-right:0.191cm;"
| style="color:#252525;" |
|| <span style="color:#000000;">In the terminal, type </span><span style="color:#000000;">'''cargo run'''</span>

<span style="color:#000000;">We can see the content of the file</span><span style="color:#000000;">''' output.txt '''</span><span style="color:#000000;">is displayed.</span>
|- style="border:1pt solid #000000;padding-top:0cm;padding-bottom:0cm;padding-left:0.206cm;padding-right:0.191cm;"
| style="color:#000000;" |
|| Next we will see how to append a file.

|- style="border:1pt solid #000000;padding-top:0cm;padding-bottom:0cm;padding-left:0.206cm;padding-right:0.191cm;"
| style="color:#000000;" |
|| <span style="color:#252525;">Clear the code window and r</span>eplace the code from the code file as shown<span style="color:#252525;">.</span>
|- style="border:1pt solid #000000;padding-top:0cm;padding-bottom:0cm;padding-left:0.206cm;padding-right:0.191cm;"
|| <div style="color:#000000;">use std::fs::OpenOptions;</div>

<div style="color:#000000;">use std::io::Write;</div>

f<span style="color:#000000;">n main() -> std::io::Result<()> {</span>

<div style="color:#000000;">let mut file = OpenOptions::new()</div>

<div style="color:#000000;">.append(true)</div>

<div style="color:#000000;">.open("output.txt")?;</div>

<span style="color:#000000;">file.write_all(b"\nThis is an appended line.")?;</span>

<span style="background-color:#ffffff;">println!("Data added to the file");</span>

<span style="color:#000000;">Ok(())</span>

<div style="color:#000000;">}</div>
|| <span style="color:#000000;">'''OpenOptions'''</span><span style="color:#000000;"> is used for more advanced operations</span>.

Operations <span style="color:#000000;">like appending, reading and writing can be done simultaneously.</span>

<span style="color:#000000;">'''.append(true)</span><span style="color:#000000;"> </span>method '''<span style="color:#000000;">e</span><span style="color:#000000;">nables the append mode</span>.

<span style="color:#000000;">New data will be </span>appended<span style="color:#000000;"> at the end of the file instead of overwriting</span>.

It o<span style="color:#000000;">pens </span><span style="color:#000000;">'''output.txt '''</span><span style="color:#000000;">file</span><span style="color:#000000;">''' '''</span><span style="color:#000000;">with the ? which handles errors (</span>For example<span style="color:#000000;">., if the file doesn’t exist).</span>

<span style="color:#000000;">'''file.write_all '''</span><span style="color:#000000;">writes a newline followed by the text "This is an appended line." </span>

Save the program.
|- style="border:1pt solid #000000;padding-top:0cm;padding-bottom:0cm;padding-left:0.206cm;padding-right:0.191cm;"
| style="color:#000000;" |
|| <div style="color:#252525;">Run the program to see the output.</div>

<div style="color:#252525;">We see the message “'''Data added to the file”'''.</div>

Let us open the '''output.txt. '''

We can see the data is added at the end of the file.
|- style="border:1pt solid #000000;padding-top:0cm;padding-bottom:0cm;padding-left:0.206cm;padding-right:0.191cm;"
| style="color:#252525;" |
| style="color:#252525;" | Next we see how to delete a file.
|- style="border:1pt solid #000000;padding-top:0cm;padding-bottom:0cm;padding-left:0.206cm;padding-right:0.191cm;"
| style="color:#252525;" |
|| <span style="color:#252525;">Clear the code window and r</span>eplace the code from the code file as shown<span style="color:#252525;">.</span>
|- style="border:1pt solid #000000;padding-top:0cm;padding-bottom:0cm;padding-left:0.206cm;padding-right:0.191cm;"
|| <div style="color:#000000;">use std::fs;</div>

<div style="color:#000000;">fn main() -> std::io::Result<()> {</div>

<div style="color:#000000;">fs::remove_file("output.txt")?;</div>

<div style="color:#000000;">println!("File deleted");</div>

<div style="color:#000000;">Ok(())</div>

<div style="color:#000000;">}</div>
|| <span style="color:#000000;">'''remove_file'''</span><span style="color:#000000;"> method deletes the file named </span><span style="color:#000000;">'''output.txt '''</span><span style="color:#000000;">from the current directory.</span>

<span style="color:#000000;">If the file doesn’t exist or if you don’t have permission, </span>it<span style="color:#000000;"> returns an error.</span>

<div style="color:#000000;">If the file is deleted successfully, “File Deleted” message is printed.</div>

Save the program.
|- style="border:1pt solid #000000;padding-top:0cm;padding-bottom:0cm;padding-left:0.206cm;padding-right:0.191cm;"
| style="color:#000000;" |
|| <div style="color:#252525;">Run the program to see the output.</div>

<span style="color:#252525;">We see the message “</span>File Deleted”<span style="color:#252525;">.</span>
|- style="border:1pt solid #000000;padding-top:0cm;padding-bottom:0cm;padding-left:0.206cm;padding-right:0.191cm;"
| style="color:#000000;" |
|| <div style="color:#000000;">This brings us to the end of this tutorial.</div>

<div style="color:#000000;">Let us summarize. </div>
|- style="border:1pt solid #000000;padding-top:0cm;padding-bottom:0cm;padding-left:0.206cm;padding-right:0.191cm;"
|| <span style="color:#000000;">'''Slide 8'''</span>
|| As an assignment,

<div style="color:#000000;">Write a Rust program to do the following steps in order:</div>

* <div style="margin-left:1.27cm;margin-right:0cm;">Create a file named '''notes.txt.'''</div>
* <div style="margin-left:1.27cm;margin-right:0cm;">Write the below text into the file:</div>
* <div style="margin-left:1.27cm;margin-right:0cm;">Reopen the same file in append mode and add one more line:</div>
* <div style="margin-left:1.27cm;margin-right:0cm;">Read back the entire content of the file and print them on the console.</div>

|- style="border:1pt solid #000000;padding-top:0cm;padding-bottom:0cm;padding-left:0.206cm;padding-right:0.191cm;"
| style="color:#000000;" | '''Slide 9 Thank You'''
| style="color:#000000;" | Thanks for joining.
|-
|}
<div style="margin-left:-1.588cm;margin-right:-1.429cm;"></div>

@@ Line 36: / Line 36: @@
-|| '''File Input/Output'''operations are done using the below modules from the Standard Library.
+|| '''File Input/Output ''' operations are done using the below modules from the Standard Library.
 * '''std::fs ''' is a module for file handling
 *  '''std::io ''' is a module for reading and writing
@@ Line 126: / Line 126: @@
 In the main function, we return io::Result<()>.
-'''File::open()''' method opens ''' output.txt '''filein ''' read-only''' mode.
+'''File::open()''' method opens ''' output.txt '''file in ''' read-only''' mode.
 Question mark(?) propagates an error if the file doesn’t exist or can’t be opened.
@@ Line 143: / Line 143: @@
 || In the terminal, type '''cargo run'''.
-We can see the content of the file ''' output.txt '''is displayed.
+We can see the content of the file ''' output.txt ''' is displayed.
 |-
 ||
@@ Line 171: / Line 171: @@
+}
-|| '''OpenOptions'''is used for more advanced operations.
+|| '''OpenOptions''' is used for more advanced operations.
 Operations like appending, reading and writing can be done simultaneously.

@@ Line 7: / Line 7: @@
 '''
 Title Slide'''
-|| Welcome to the Spoken Tutorial on '''File Handling '''in '''Rust.'''
+|| Welcome to the Spoken Tutorial on '''File Handling '''in '''Rust'''.
 |-
 || '''Slide 2'''
@@ Line 36: / Line 36: @@
-|| '''File Input/Output'''operations are done using the below modules from the Standard Library
+|| '''File Input/Output'''operations are done using the below modules from the Standard Library.
 * '''std::fs ''' is a module for file handling
 *  '''std::io ''' is a module for reading and writing
@@ Line 70: / Line 70: @@
 '''File''' is used to create, open and work with files.
-Then we import the '''io'''module and '''write''' the trait.
+Then we import the '''io''' module and '''write''' the trait.
-Here '''self''' means importing''' std::io '''itself as ''' io.'''
+Here '''self''' means importing''' std::io ''' itself as ''' io'''.
-In the main function, '''File::create()''' method creates a new file called '''output.txt.'''
+In the main function, '''File::create()''' method creates a new file called '''output.txt'''.
 If it already exists, it truncates it before writing, otherwise creates a new file.
-'''Write_all '''writes all the ''' bytes''' from the given byte string into the file.
+'''Write_all ''' writes all the ''' bytes''' from the given '''byte''' string into the file.
 The''' b''' before the string literal means that we are writing '''raw bytes''', not a String.
@@ Line 84: / Line 84: @@
 This is often safer and faster for low-level writing.
-The ? operator is used to handle any write failure.
+The question mark(?) operator is used to handle any write failure.
 After successful writing, we print a successful message.
@@ Line 93: / Line 93: @@
 |-
 || Open and show the file
-|| In the terminal,type '''cargo run ''' to see the output.
+|| In the terminal, type '''cargo run ''' to see the output.
 Let us open the '''output.txt.'''
@@ Line 126: / Line 126: @@
 In the main function, we return io::Result<()>.
-'''File::open()''' method opens ''' output.txt '''filein ''' read-only'''mode.
+'''File::open()''' method opens ''' output.txt '''filein ''' read-only''' mode.
-? propagates an error if the file doesn’t exist or can’t be opened.
+Question mark(?) propagates an error if the file doesn’t exist or can’t be opened.
 We create an empty String to hold the file’s contents.
@@ Line 179: / Line 179: @@
 New data will be appended at the end of the file instead of overwriting.
-It opens '''output.txt  file'''  with the ? which handles errors.
+It opens '''output.txt  file'''  with the question mark(?) which handles errors.
-For example., if the file doesn’t exist.
+For example, if the file doesn’t exist.
 '''file.write_all '''writes a newline followed by the text "This is an appended line."
@@ Line 224: / Line 224: @@
 || Run the program to see the output.
-We see the message “File Deleted”.
+We see the message “File deleted”.
 |-
 ||

@@ Line 14: / Line 14: @@
 || In this tutorial, we will learn about:
 * File operations
-* Input and Outputoperations
+* Input and Output operations
 |-
@@ Line 37: / Line 37: @@
 || '''File Input/Output'''operations are done using the below modules from the Standard Library
-* '''std::fs '''is a module for file handling
+* '''std::fs ''' is a module for file handling
-*  '''std::io '''is a module for reading and writing
+*  '''std::io ''' is a module for reading and writing
 |-
@@ Line 66: / Line 66: @@
+}
-|| We import the '''File'''struct from the '''std:fs'''module.
+|| We import the '''File struct''' from the '''std:fs''' module.
-'''File'''is used to create, openand workwith files.
+'''File''' is used to create, open and work with files.
-Then we import the '''io'''module and '''write'''the trait.
+Then we import the '''io'''module and '''write''' the trait.
-Here '''self'''means importing''' std::io '''itself as''' io.'''
+Here '''self''' means importing''' std::io '''itself as ''' io.'''
-In the main function, '''File::create()'''method creates a new file called '''output.txt.'''
+In the main function, '''File::create()''' method creates a new file called '''output.txt.'''
-If it already exists, it truncates it before writing. otherwise creates a new file.
+If it already exists, it truncates it before writing, otherwise creates a new file.
-'''Write_all '''writes all the''' bytes'''from the given byte string into the file.
+'''Write_all '''writes all the ''' bytes''' from the given byte string into the file.
 The''' b''' before the string literal means that we are writing '''raw bytes''', not a String.
@@ Line 93: / Line 93: @@
 |-
 || Open and show the file
-|| In the terminal,type '''cargo run '''to see the output.
+|| In the terminal,type '''cargo run ''' to see the output.
-Let us open the '''output.txt.''' We can see the data written to the file.
+Let us open the '''output.txt.'''
 |-
 ||
@@ Line 120: / Line 122: @@
+}
-|| We import the '''Read trait '''from the '''io'''module.
+|| We import the '''Read trait ''' from the '''io''' module.
 In the main function, we return io::Result<()>.
-File::open()method opens''' output.txt '''filein '''read-only'''mode.
+'''File::open()''' method opens ''' output.txt '''filein ''' read-only'''mode.
 ? propagates an error if the file doesn’t exist or can’t be opened.
@@ Line 139: / Line 141: @@
 |-
 || To run type '''cargo run''' in the terminal.
-|| In the terminal, type '''cargo run'''
+|| In the terminal, type '''cargo run'''.
-We can see the content of the file''' output.txt '''is displayed.
+We can see the content of the file ''' output.txt '''is displayed.
 |-
 ||
@@ Line 173: / Line 175: @@
 Operations like appending, reading and writing can be done simultaneously.
-'''.append(true)method '''enables the append mode.
+'''.append(true)method ''' enables the append mode.
-New data will be appendedat the end of the file instead of overwriting.
+It opens '''output.txt  file'''  with the ? which handles errors.
-It opens '''output.txt '''file''' '''with the ? which handles errors (For example., if the file doesn’t exist).
+For example., if the file doesn’t exist.
 '''file.write_all '''writes a newline followed by the text "This is an appended line."
@@ Line 188: / Line 192: @@
 We see the message “'''Data added to the file”'''.
-Let us open the '''output.txt. '''
+Let us open the '''output.txt '''.
 We can see the data is added at the end of the file.
@@ Line 209: / Line 213: @@
+}
-|| '''remove_file'''method deletes the file named '''output.txt ''' from the current directory.
+|| '''remove_file''' method deletes the file named '''output.txt ''' from the current directory.
 If the file doesn’t exist or if you don’t have permission, it returns an error.
@@ Line 234: / Line 238: @@
 Write a Rust program to do the following steps in order:
-* Create a file named '''notes.txt.'''
+* Create a file named '''notes.txt'''
 * Write the below text into the file:
 * Reopen the same file in append mode and add one more line:
-* Read back the entire content of the file and print them on the console.
+* Read back the entire contents of the file and print them on the console.
 |-