Corpus-NZ/Code-Syntax-Expanded · Datasets at Hugging Face

wrong_code stringlengths 3 123	correct_code stringlengths 3 155	explanation stringclasses 101 values	language stringclasses 26 values
fs.readFile('log.txt', (err,data) => {{ if(err) throw err; }});	fs.readFile('log.txt', (err,data) => {{ if(err) {{ console.error(err); return; }} }});	Better error handling.	Node.js
<a href='https://example.com' target='_blank'>	<a href='https://example.com' target='_blank' rel='noopener'>	Add rel for security.	HTML
@media screen {{ body {{}} }}	@media screen {{ body {{}} }}	Correct.	CSS
[99, 69, 44	[99, 69, 44]	Close bracket.	Python
var x int	var x int	Correct.	Go
let v=vec![46,45,67]; let first=&v[0]; v.push(88);	let mut v=vec![46,45,67]; let first=v[0]; v.push(88);	Copy instead of reference.	Rust
class Child Base:	class Child(Base):	Inheritance uses parentheses.	Python
let s1 = String::from("data"); let text2 = s1; println!("{{}}", s1);	let s1 = String::from("data"); let text2 = s1.clone(); println!("{{}}", s1);	Clone to avoid move.	Rust
for (int i=0; i<94; i++) {{}}	for (int i=0; i<94; i++) {{}}	Correct.	Java
class Product {{ int item; }} obj.item=5;	class Product {{ public int item; }} obj.item=5;	Make field public.	Java
lambda x: x+1	lambda x: x+1	Correct lambda.	Python
class = 'world'	class_name = 'world'	'class' is a keyword.	Python
def render(): print('result')	def render(): print('result')	Indent function body.	Python
<person age=32>	<person age="32">	Quote attribute.	XML
let data = 92; data += 1;	let mut data = 92; data += 1;	Need mut to modify.	Rust
Write-Host 'message'	Write-Host 'message'	Correct.	PowerShell
$values[59]	if ($values.Count -gt 59) {{ $values[59] }}	Check bounds.	PowerShell
<div><p>output</div></p>	<div><p>output</p></div>	Nest properly.	HTML
switch(bar){{ case 51: break; }}	switch(bar){{ case 51: break; default: break; }}	Add default case.	Java
<p>info <b>test</p></b>	<p>info <b>test</b></p>	Nest properly.	HTML
for y in range(74) print(y)	for y in range(74): print(y)	Colon after for.	Python
if num > 80 print('world')	if num > 80: print('world')	Colon missing after if.	Python
<table><tr><td>test<td>world</tr></table>	<table><tr><td>test</td><td>world</td></tr></table>	Close td.	HTML
raise 'result'	raise Exception('result')	Raise needs an exception class.	Python
{{"name":"value",}}	{{"name":"value"}}	Remove trailing comma.	JSON
if a = 12	if a == 12	Use ==.	MATLAB
jwt.sign({{id:37}}, 'key');	jwt.sign({{id:37}}, 'key', {{expiresIn:'7d'}});	Add expiration.	Node.js
list: - item1 - item2	list: - item1 - item2	Correct.	YAML
cin >> foo cout << foo;	cin >> foo; cout << foo;	Add semicolon.	C++
x <- 5; if (x > 3) print('large')	x <- 5; if (x > 3) print('large')	Correct.	R
assert y > 26	assert y > 26	Correct.	Python
let count = 93;	let count = 93;	Correct.	JavaScript
function process() {{ echo 'info'; }}	function process() {{ echo 'info'; }}	Correct.	PHP
int* p = nullptr; *p=5;	int* p = new int; *p=5;	Allocate memory.	C++
math.sqrt(22)	import math math.sqrt(22)	Import module first.	Python
x = 5; if x > 3, disp('large'), end	x = 5; if x > 3, disp('large'), end	Correct.	MATLAB
{{'status':'data'}}	{{"status":"data"}}	Use double quotes.	JSON
x := 100	x := 100	Correct.	Go
[98, 50, 71	[98, 50, 71]	Close bracket.	Ruby
$x = 5; print $x	$x = 5; print $x;	Missing semicolon.	Perl
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('data')); app.listen(11);	const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('data')); app.listen(11, () => console.log('listening'));	Add callback.	Node.js
h1 {{ font-size:63px color:#333; }}	h1 {{ font-size:63px; color:#333; }}	Add semicolon.	CSS
int values[92]; values[92]=5;	int values[92]; if(92<92){{}} else values[92]=5;	Bounds check.	C++
{ "name": "test" }	{ "name": "test" }	Correct.	JSON
'value' + 38	'value' + str(38)	Can't add int to string.	Python
void main() {{ print('info') }}	void main() {{ print('info'); }}	Add semicolon.	Dart
else print('value')	else: print('value')	Colon after else.	Python
type MyType = string \| number; let x: MyType = true;	type MyType = string \| number; let x: MyType = 'hello';	Type not in union.	TypeScript
// comment	/* comment */	Use /* */.	CSS
var x = 5; x = true	var x = 5; x = 10	Type mismatch.	Kotlin
cin >> c;	int c; cin >> c;	Declare variable.	C++
<hr></hr>	<hr>	Self-closing.	HTML
<root><child>text</child></root>	<root><child>text</child></root>	Correct.	XML
$x = 5; if ($x -eq 5) { Write-Host 'yes' }	$x = 5; if ($x -eq 5) { Write-Host 'yes' }	Correct.	PowerShell
function process(c) print(c) end	function process(c) print(c) end	Correct.	Lua
y > 74 & x < 17	y > 74 and x < 17	Use 'and' not '&'.	Python
Post.save();	Post.save().then(()=>{{}}).catch(err=>{{}});	Handle promise.	Node.js
list[16]	if (list.indices.contains(16)) list[16]	Check index.	Kotlin
ArrayList list = new ArrayList();	ArrayList<String> list = new ArrayList<>();	Use generics.	Java
if item > 76 puts 'info'	if item > 76 puts 'info' end	Add 'end'.	Ruby
String x = 'value';	String x = "value";	Double quotes.	Java
name: output age: 67	name: output age: 67	Correct.	YAML
if (a = 54)	if (a == 54)	Use ==.	R
SELECT id status FROM items;	SELECT id, status FROM items;	Add comma.	SQL
const temp;	const temp = 53;	Initialize const.	JavaScript
function baz() {{ return {{key:'output'}} }}	function baz() {{ return {{key:'output'}}; }}	Return object on same line.	JavaScript
handle	handle()	Add parentheses.	Kotlin
def foo puts 'hello' end	def foo puts 'hello' end	Correct.	Ruby
List(63,5,45)	List(63,5,45)	Correct.	Scala
let x: Int = 'result'	let x: String = 'result'	Fix type.	Swift
if (bar = 98)	if (bar == 98)	Use ==.	Scala
function baz(val:string){{return val;}} baz(54);	function baz(val:string){{return val;}} baz('output');	Pass correct type.	TypeScript
let s = String::from("data"); let borrow=&s; s.push_str("!");	let mut s = String::from("data"); let borrow=&s; println!("{{}}", borrow); s.push_str("!");	Cannot mutate while borrowed.	Rust
console.log('output'	console.log('output')	Close parenthesis.	JavaScript
let foo = 62; let foo = 78;	let foo = 62; foo = 78;	Duplicate declaration.	JavaScript
UPDATE products SET id='result' WHERE email=52	UPDATE products SET id='result' WHERE email=52;	Add semicolon.	SQL
int bar = 'hello';	String bar = 'hello';	Type mismatch.	Dart
if b = 9	if b == 9	Use ==.	Go
def handle(foo): return foo + 1	def handle(foo): return foo + 1	Correct.	Python
div {{ color=green; }}	div {{ color: green; }}	Use colon.	CSS
yield c	yield c	Correct yield.	Python
fmt.Println 'info'	fmt.Println('info')	Missing parentheses.	Go
$x = 5; echo $x	$x = 5; echo $x;	Missing semicolon.	PHP
let c: i32 = "test";	let c: &str = "test";	Type mismatch.	Rust
let item: number = 'hello';	let item: string = 'hello';	Fix type.	TypeScript
<?php // code ?>	<?php // code ?>	Correct.	PHP
if z = 60 then print('message') end	if z == 60 then print('message') end	Use ==.	Lua
<div color=#333>	<div style='color:#333;'>	Use style attribute.	CSS
if (item = 80) {{}}	if (item === 80) {{}}	Use === for equality.	JavaScript
if (data = 66)	if (data == 66)	Use ==.	C++
println('world')	println("world")	Double quotes.	Scala
int x; System.out.println(x);	int x = 0; System.out.println(x);	Initialize variable.	Java
for i in $(ls); do echo $i; done	for i in $(ls); do echo $i; done	Correct.	Shell
if (y) console.log('yes') else console.log('no')	if (y) console.log('yes'); else console.log('no');	Missing semicolon.	JavaScript
if (c = 49) {}	if (c == 49) {}	Use ==.	Dart
SELECT * FROM products WHRE status=42;	SELECT * FROM products WHERE status=42;	Fix WHERE.	SQL
age: value id: test,	age: value id: test	Remove comma.	YAML
function handle(): void {{ return 95; }}	function handle(): number {{ return 95; }}	Return type mismatch.	TypeScript
count = output	count = 'output'	Quote strings.	Python
if data = 47 {{}}	if data == 47 {{}}	Use ==.	Swift

fs.readFile('log.txt', (err,data) => {{ if(err) throw err; }});

fs.readFile('log.txt', (err,data) => {{ if(err) {{ console.error(err); return; }} }});

Better error handling.

Node.js

Add rel for security.

HTML

@media screen {{ body {{}} }}

Correct.

CSS

[99, 69, 44

[99, 69, 44]

Close bracket.

Python

var x int

Correct.

Go

let v=vec![46,45,67]; let first=&v[0]; v.push(88);

let mut v=vec![46,45,67]; let first=v[0]; v.push(88);

Copy instead of reference.

Rust

class Child Base:

class Child(Base):

Inheritance uses parentheses.

Python

let s1 = String::from("data"); let text2 = s1; println!("{{}}", s1);

let s1 = String::from("data"); let text2 = s1.clone(); println!("{{}}", s1);

Clone to avoid move.

Rust

for (int i=0; i<94; i++) {{}}

Correct.

Java

class Product {{ int item; }} obj.item=5;

class Product {{ public int item; }} obj.item=5;

Make field public.

Java

lambda x: x+1

Correct lambda.

Python

class = 'world'

class_name = 'world'

'class' is a keyword.

Python

def render(): print('result')

Indent function body.

Python

Quote attribute.

XML

let data = 92; data += 1;

let mut data = 92; data += 1;

Need mut to modify.

Rust

Write-Host 'message'

Correct.

PowerShell

$values[59]

if ($values.Count -gt 59) {{ $values[59] }}

Check bounds.

PowerShell

<div><p>output</div></p>

<div><p>output</p></div>

Nest properly.

HTML

switch(bar){{ case 51: break; }}

switch(bar){{ case 51: break; default: break; }}

Add default case.

Java

Nest properly.

HTML

for y in range(74) print(y)

for y in range(74): print(y)

Colon after for.

Python

if num > 80 print('world')

if num > 80: print('world')

Colon missing after if.

Python

<table><tr><td>test<td>world</tr></table>

<table><tr><td>test</td><td>world</td></tr></table>

Close td.

HTML

raise 'result'

raise Exception('result')

Raise needs an exception class.

Python

Remove trailing comma.

JSON

if a = 12

if a == 12

Use ==.

MATLAB

jwt.sign({{id:37}}, 'key');

jwt.sign({{id:37}}, 'key', {{expiresIn:'7d'}});

Add expiration.

Node.js

list: - item1 - item2

Correct.

YAML

cin >> foo cout << foo;

cin >> foo; cout << foo;

Add semicolon.

C++

x <- 5; if (x > 3) print('large')

Correct.

R

assert y > 26

Correct.

Python

let count = 93;

Correct.

JavaScript

function process() {{ echo 'info'; }}

Correct.

PHP

int* p = nullptr; *p=5;

int* p = new int; *p=5;

Allocate memory.

C++

math.sqrt(22)

import math math.sqrt(22)

Import module first.

Python

x = 5; if x > 3, disp('large'), end

Correct.

MATLAB

Use double quotes.

JSON

x := 100

Correct.

Go

[98, 50, 71

[98, 50, 71]

Close bracket.

Ruby

$x = 5; print $x

$x = 5; print $x;

Missing semicolon.

Perl

const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('data')); app.listen(11);

const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('data')); app.listen(11, () => console.log('listening'));

Add callback.

Node.js

h1 {{ font-size:63px color:#333; }}

h1 {{ font-size:63px; color:#333; }}

Add semicolon.

CSS

int values[92]; values[92]=5;

int values[92]; if(92<92){{}} else values[92]=5;

Bounds check.

C++

{ "name": "test" }

Correct.

JSON

'value' + 38

'value' + str(38)

Can't add int to string.

Python

void main() {{ print('info') }}

void main() {{ print('info'); }}

Add semicolon.

Dart

else print('value')

else: print('value')

Colon after else.

Python

type MyType = string | number; let x: MyType = true;

type MyType = string | number; let x: MyType = 'hello';

Type not in union.

TypeScript

// comment

/* comment */

Use /* */.

CSS

var x = 5; x = true

var x = 5; x = 10

Type mismatch.

Kotlin

cin >> c;

int c; cin >> c;

Declare variable.

C++

<hr>

Self-closing.

HTML

Correct.

XML

$x = 5; if ($x -eq 5) { Write-Host 'yes' }

Correct.

PowerShell

function process(c) print(c) end

Correct.

Lua

y > 74 & x < 17

y > 74 and x < 17

Use 'and' not '&'.

Python

Post.save();

Post.save().then(()=>{{}}).catch(err=>{{}});

Handle promise.

Node.js

list[16]

if (list.indices.contains(16)) list[16]

Check index.

Kotlin

ArrayList list = new ArrayList();

ArrayList<String> list = new ArrayList<>();

Use generics.

Java

if item > 76 puts 'info'

if item > 76 puts 'info' end

Add 'end'.

Ruby

String x = 'value';

String x = "value";

Double quotes.

Java

name: output age: 67

Correct.

YAML

if (a = 54)

if (a == 54)

Use ==.

R

SELECT id status FROM items;

SELECT id, status FROM items;

Add comma.

SQL

const temp;

const temp = 53;

Initialize const.

JavaScript

function baz() {{ return {{key:'output'}} }}

function baz() {{ return {{key:'output'}}; }}

Return object on same line.

JavaScript

handle

handle()

Add parentheses.

Kotlin

def foo puts 'hello' end

Correct.

Ruby

List(63,5,45)

Correct.

Scala

let x: Int = 'result'

let x: String = 'result'

Fix type.

Swift

if (bar = 98)

if (bar == 98)

Use ==.

Scala

function baz(val:string){{return val;}} baz(54);

function baz(val:string){{return val;}} baz('output');

Pass correct type.

TypeScript

let s = String::from("data"); let borrow=&s; s.push_str("!");

let mut s = String::from("data"); let borrow=&s; println!("{{}}", borrow); s.push_str("!");

Cannot mutate while borrowed.

Rust

console.log('output'

console.log('output')

Close parenthesis.

JavaScript

let foo = 62; let foo = 78;

let foo = 62; foo = 78;

Duplicate declaration.

JavaScript

UPDATE products SET id='result' WHERE email=52

UPDATE products SET id='result' WHERE email=52;

Add semicolon.

SQL

int bar = 'hello';

String bar = 'hello';

Type mismatch.

Dart

if b = 9

if b == 9

Use ==.

Go

def handle(foo): return foo + 1

Correct.

Python

div {{ color=green; }}

div {{ color: green; }}

Use colon.

CSS

yield c

Correct yield.

Python

fmt.Println 'info'

fmt.Println('info')

Missing parentheses.

Go

$x = 5; echo $x

$x = 5; echo $x;

Missing semicolon.

PHP

let c: i32 = "test";

let c: &str = "test";

Type mismatch.

Rust

let item: number = 'hello';

let item: string = 'hello';

Fix type.

TypeScript

<?php // code ?>

Correct.

PHP

if z = 60 then print('message') end

if z == 60 then print('message') end

Use ==.

Lua

Use style attribute.

CSS

if (item = 80) {{}}

if (item === 80) {{}}

Use === for equality.

JavaScript

if (data = 66)

if (data == 66)

Use ==.

C++

println('world')

println("world")

Double quotes.

Scala

int x; System.out.println(x);

int x = 0; System.out.println(x);

Initialize variable.

Java

for i in $(ls); do echo $i; done

Correct.

Shell

if (y) console.log('yes') else console.log('no')

if (y) console.log('yes'); else console.log('no');

Missing semicolon.

JavaScript

if (c = 49) {}

if (c == 49) {}

Use ==.

Dart

SELECT * FROM products WHRE status=42;

SELECT * FROM products WHERE status=42;

Fix WHERE.

SQL

age: value id: test,

age: value id: test

Remove comma.

YAML

function handle(): void {{ return 95; }}

function handle(): number {{ return 95; }}

Return type mismatch.

TypeScript

count = output

count = 'output'

Quote strings.

Python

if data = 47 {{}}

if data == 47 {{}}

Use ==.

Swift