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
while read line; do echo $line; done < config.json	while read line; do echo $line; done < config.json	Correct.	Shell
def test(): print('value')	def test(): print('value')	Indent function body.	Python
var x int = 'value'	var x string = 'value'	Type mismatch.	Go
let str = String::from("value"); let borrow=&str; str.push_str("!");	let mut str = String::from("value"); let borrow=&str; println!("{{}}", borrow); str.push_str("!");	Cannot mutate while borrowed.	Rust
int arr[61]; arr[61]=5;	int arr[61]; if(61<61){{}} else arr[61]=5;	Bounds check.	C++
if x = 56:	if x == 56:	Use == for comparison.	Python
function bar(): void {{ return 21; }}	function bar(): number {{ return 21; }}	Return type mismatch.	TypeScript
<center>output</center>	<div style='text-align:center;'>output</div>	Use CSS.	HTML
int x; System.out.println(x);	int x = 0; System.out.println(x);	Initialize variable.	Java
UPDATE items SET age='result' WHERE role=49	UPDATE items SET age='result' WHERE role=49;	Add semicolon.	SQL
class Product {{ int index; }};	class Product {{ public: int index; }};	Make public.	C++
values[56]	if (values.indices.contains(56)) values[56]	Check index.	Kotlin
$items[10]	if ($items.Count -gt 10) {{ $items[10] }}	Check bounds.	PowerShell
p {{ color: #333 }}	p {{ color: #333; }}	Add semicolon.	CSS
package main func main() {{}}	package main import 'fmt' func main() {{}}	Import needed.	Go
class = 'value'	class_name = 'value'	'class' is a keyword.	Python
User.save();	User.save().then(()=>{{}}).catch(err=>{{}});	Handle promise.	Node.js
const c = 34; c = 59;	let c = 34; c = 59;	Cannot reassign const.	JavaScript
const z;	const z = 17;	Initialize const.	JavaScript
print 'data'	print('data')	print needs parentheses.	Python
if (a = 3)	if (a == 3)	Use ==.	R
let index: i32 = "world";	let index: &str = "world";	Type mismatch.	Rust
if z = 46	if z == 46	Use ==.	Ruby
if [ $val = 39 ]; then	if [ "$val" = 39 ]; then	Quote variable.	Shell
<div color=#fff>	<div style='color:#fff;'>	Use style attribute.	CSS
{{'age':'data'}}	{{"age":"data"}}	Use double quotes.	JSON
let num: number \| null = null; num.toFixed(15);	let num: number \| null = null; if(num!==null) num.toFixed(15);	Null check.	TypeScript
match y {{ 1 => {{}} }}	match y {{ 1 => {{}} _ => {{}} }}	Match must be exhaustive.	Rust
const http = require('http'); http.createServer((req,res) => res.end('world')).listen(67);	const http = require('http'); http.createServer((req,res) => res.end('world')).listen(67);	Correct.	Node.js
cin >> index;	int index; cin >> index;	Declare variable.	C++
$x = 5; echo $x	$x = 5; echo $x;	Missing semicolon.	PHP
h1 {{ font-size:47px color:#fff; }}	h1 {{ font-size:47px; color:#fff; }}	Add semicolon.	CSS
DELETE FROM products WHERE age=4	DELETE FROM products WHERE age=4;	Add semicolon.	SQL
my @arr = (94,7,35);	my @arr = (94,7,35);	Correct.	Perl
function baz() {{ return {{key:'result'}} }}	function baz() {{ return {{key:'result'}}; }}	Return object on same line.	JavaScript
data(10)	if length(data) >= 10, data(10), end	Check length.	MATLAB
@media screen {{ body {{}} }}	@media screen {{ body {{}} }}	Correct.	CSS
<p>result <b>test</p></b>	<p>result <b>test</b></p>	Nest properly.	HTML
Write-Host 'world'	Write-Host 'world'	Correct.	PowerShell
var x = 5; x = "hello"	var x = "hello"	Type mismatch.	Swift
a > 57 & y < 50	a > 57 and y < 50	Use 'and' not '&'.	Python
if (x = 3) {{}}	if (x === 3) {{}}	Use === for equality.	JavaScript
data[84]	if data.indices.contains(84) {{ data[84] }}	Check index.	Swift
<ul><li>data<li>world</ul>	<ul><li>data</li><li>world</li></ul>	Close li.	HTML
if ($y = 4)	if ($y == 4)	Use ==.	Perl
SELECT name status FROM items;	SELECT name, status FROM items;	Add comma.	SQL
<a href='https://demo.net' target='_blank'>	<a href='https://demo.net' target='_blank' rel='noopener'>	Add rel for security.	HTML
def process puts 'value' end	def process puts 'value' end	Correct.	Ruby
object Product {{ def main(args: Array[String]) = println("value") }}	object Product {{ def main(args: Array[String]): Unit = println("value") }}	Add return type Unit.	Scala
with open('input.csv') as fp: data = fp.read()	with open('input.csv') as fp: data = fp.read()	Correct.	Python
if c = 1 {{}}	if c == 1 {{}}	Use ==.	Swift
const int x; x = 5;	const int x = 5;	Const must be initialized.	C++
if (bar = 42)	if (bar == 42)	Use ==.	Scala
if index = 4	if index == 4	Use ==.	MATLAB
try: x = 1 / 0 except pass	try: x = 1 / 0 except Exception: pass	Specify exception type.	Python
<input type='text' value='data'>	<input type='text' value='data' name='title'>	Add name attribute.	HTML
x <- 5; if (x > 3) print('large')	x <- 5; if (x > 3) print('large')	Correct.	R
echo 'info'	echo 'info';	Add semicolon.	PHP
var x int	var x int	Correct.	Go
<person age=70>	<person age="70">	Quote attribute.	XML
<?php // code ?>	<?php // code ?>	Correct.	PHP
println('message')	println("message")	Double quotes.	Scala
if result = 50	if result == 50	Use ==.	Go
for (index in values)	for (index of values)	for...in iterates keys.	JavaScript
String z = 'hello';	String z = "hello";	Double quotes.	Java
List<int> list = [1,2,3];	List<int> list = [1,2,3];	Correct.	Dart
let vec=vec![94,16,38]; let first=&vec[0]; vec.push(60);	let mut vec=vec![94,16,38]; let first=vec[0]; vec.push(60);	Copy instead of reference.	Rust
for (int i=0; i<29; i++) {{}}	for (int i=0; i<29; i++) {{}}	Correct.	Java
arr.forEach(function(y) {{ console.log(y); }})	arr.forEach((y) => {{ console.log(y); }})	Arrow functions are cleaner.	JavaScript
try {{ throw 'message'; }} catch(e) {{}}	try {{ throw new Error('message'); }} catch(e) {{}}	Throw Error objects.	JavaScript
let b = 98; let b = 38;	let b = 98; b = 38;	Duplicate declaration.	JavaScript
x := 82	x := 82	Correct.	Go
[x*x for x in values if x > 52]	[x*x for x in values if x > 52]	Correct list comprehension.	Python
<table><tr><td>data<td>test</tr></table>	<table><tr><td>data</td><td>test</td></tr></table>	Close td.	HTML
name: output name: test,	name: output name: test	Remove comma.	YAML
function test() {{ echo 'test'; }}	function test() {{ echo 'test'; }}	Correct.	PHP
INSERT INTO products VALUES ('result',13)	INSERT INTO products (age, status) VALUES ('result',13);	Specify columns.	SQL
if num = 18 then print('test') end	if num == 18 then print('test') end	Use ==.	Lua
b == '66'	b === 66	Use strict equality.	JavaScript
$index = 32; if ($index = 32) {{}}	$index = 32; if ($index == 32) {{}}	Use ==.	PHP
x = 5; if x > 3, disp('large'), end	x = 5; if x > 3, disp('large'), end	Correct.	MATLAB
fs.readFile('input.csv', (err,data) => {{ if(err) throw err; }});	fs.readFile('input.csv', (err,data) => {{ if(err) {{ console.error(err); return; }} }});	Better error handling.	Node.js
type MyType = string \| number; let x: MyType = true;	type MyType = string \| number; let x: MyType = 'hello';	Type not in union.	TypeScript
JOIN profiles ON products.id = profiles.status	JOIN profiles ON products.id = profiles.status	Correct.	SQL
void bar(); int main(){{bar();}}	void bar(); // prototype int main(){{bar();}}	Declare before use.	C++
<hr></hr>	<hr>	Self-closing.	HTML
if foo > 94 puts 'test'	if foo > 94 puts 'test' end	Add 'end'.	Ruby
if ($a = 27) {{}}	if ($a -eq 27) {{}}	Use -eq.	PowerShell
int &ref;	int x; int &ref = x;	Reference must be initialized.	C++
SELECT COUNT(*) FROM items	SELECT COUNT(*) FROM items;	Missing semicolon.	SQL
div {{ color=#fff; }}	div {{ color: #fff; }}	Use colon.	CSS
$x = 5; if ($x -eq 5) { Write-Host 'yes' }	$x = 5; if ($x -eq 5) { Write-Host 'yes' }	Correct.	PowerShell
<person><name>data</name><name>21</name></person	<person><name>data</name><name>21</name></person>	Add closing >.	XML
'38' + 94	38 + 94	Avoid string coercion.	JavaScript
while index > 60 index -= 1	while index > 60: index -= 1	Colon missing after while.	Python
'result' + 58	'result' + str(58)	Can't add int to string.	Python
fmt.Println 'data'	fmt.Println('data')	Missing parentheses.	Go
{{'name':18, 'name' 30}}	{{'name':18, 'name':30}}	Colon missing.	Python
if (z = 21)	if (z == 21)	Use ==.	C++
int main() {{ return 0; }}	int main() {{ return 0; }}	Correct.	C++

while read line; do echo $line; done < config.json

Correct.

Shell

def test(): print('value')

Indent function body.

Python

var x int = 'value'

var x string = 'value'

Type mismatch.

Go

let str = String::from("value"); let borrow=&str; str.push_str("!");

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

Cannot mutate while borrowed.

Rust

int arr[61]; arr[61]=5;

int arr[61]; if(61<61){{}} else arr[61]=5;

Bounds check.

C++

if x = 56:

if x == 56:

Use == for comparison.

Python

function bar(): void {{ return 21; }}

function bar(): number {{ return 21; }}

Return type mismatch.

TypeScript

<center>output</center>

<div style='text-align:center;'>output</div>

Use CSS.

HTML

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

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

Initialize variable.

Java

UPDATE items SET age='result' WHERE role=49

UPDATE items SET age='result' WHERE role=49;

Add semicolon.

SQL

class Product {{ int index; }};

class Product {{ public: int index; }};

Make public.

C++

values[56]

if (values.indices.contains(56)) values[56]

Check index.

Kotlin

$items[10]

if ($items.Count -gt 10) {{ $items[10] }}

Check bounds.

PowerShell

p {{ color: #333 }}

p {{ color: #333; }}

Add semicolon.

CSS

package main func main() {{}}

package main import 'fmt' func main() {{}}

Import needed.

Go

class = 'value'

class_name = 'value'

'class' is a keyword.

Python

User.save();

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

Handle promise.

Node.js

const c = 34; c = 59;

let c = 34; c = 59;

Cannot reassign const.

JavaScript

const z;

const z = 17;

Initialize const.

JavaScript

print 'data'

print('data')

print needs parentheses.

Python

if (a = 3)

if (a == 3)

Use ==.

R

let index: i32 = "world";

let index: &str = "world";

Type mismatch.

Rust

if z = 46

if z == 46

Use ==.

Ruby

if [ $val = 39 ]; then

if [ "$val" = 39 ]; then

Quote variable.

Shell

Use style attribute.

CSS

Use double quotes.

JSON

let num: number | null = null; num.toFixed(15);

let num: number | null = null; if(num!==null) num.toFixed(15);

Null check.

TypeScript

match y {{ 1 => {{}} }}

match y {{ 1 => {{}} _ => {{}} }}

Match must be exhaustive.

Rust

const http = require('http'); http.createServer((req,res) => res.end('world')).listen(67);

Correct.

Node.js

cin >> index;

int index; cin >> index;

Declare variable.

C++

$x = 5; echo $x

$x = 5; echo $x;

Missing semicolon.

PHP

h1 {{ font-size:47px color:#fff; }}

h1 {{ font-size:47px; color:#fff; }}

Add semicolon.

CSS

DELETE FROM products WHERE age=4

DELETE FROM products WHERE age=4;

Add semicolon.

SQL

my @arr = (94,7,35);

Correct.

Perl

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

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

Return object on same line.

JavaScript

data(10)

if length(data) >= 10, data(10), end

Check length.

MATLAB

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

Correct.

CSS

<p>result <b>test</p></b>

<p>result <b>test</b></p>

Nest properly.

HTML

Write-Host 'world'

Correct.

PowerShell

var x = 5; x = "hello"

var x = "hello"

Type mismatch.

Swift

a > 57 & y < 50

a > 57 and y < 50

Use 'and' not '&'.

Python

if (x = 3) {{}}

if (x === 3) {{}}

Use === for equality.

JavaScript

data[84]

if data.indices.contains(84) {{ data[84] }}

Check index.

Swift

<ul><li>data<li>world</ul>

<ul><li>data</li><li>world</li></ul>

Close li.

HTML

if ($y = 4)

if ($y == 4)

Use ==.

Perl

SELECT name status FROM items;

SELECT name, status FROM items;

Add comma.

SQL

Add rel for security.

HTML

def process puts 'value' end

Correct.

Ruby

object Product {{ def main(args: Array[String]) = println("value") }}

object Product {{ def main(args: Array[String]): Unit = println("value") }}

Add return type Unit.

Scala

with open('input.csv') as fp: data = fp.read()

Correct.

Python

if c = 1 {{}}

if c == 1 {{}}

Use ==.

Swift

const int x; x = 5;

const int x = 5;

Const must be initialized.

C++

if (bar = 42)

if (bar == 42)

Use ==.

Scala

if index = 4

if index == 4

Use ==.

MATLAB

try: x = 1 / 0 except pass

try: x = 1 / 0 except Exception: pass

Specify exception type.

Python

Add name attribute.

HTML

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

Correct.

R

echo 'info'

echo 'info';

Add semicolon.

PHP

var x int

Correct.

Go

Quote attribute.

XML

<?php // code ?>

Correct.

PHP

println('message')

println("message")

Double quotes.

Scala

if result = 50

if result == 50

Use ==.

Go

for (index in values)

for (index of values)

for...in iterates keys.

JavaScript

String z = 'hello';

String z = "hello";

Double quotes.

Java

List<int> list = [1,2,3];

Correct.

Dart

let vec=vec![94,16,38]; let first=&vec[0]; vec.push(60);

let mut vec=vec![94,16,38]; let first=vec[0]; vec.push(60);

Copy instead of reference.

Rust

for (int i=0; i<29; i++) {{}}

Correct.

Java

arr.forEach(function(y) {{ console.log(y); }})

arr.forEach((y) => {{ console.log(y); }})

Arrow functions are cleaner.

JavaScript

try {{ throw 'message'; }} catch(e) {{}}

try {{ throw new Error('message'); }} catch(e) {{}}

Throw Error objects.

JavaScript

let b = 98; let b = 38;

let b = 98; b = 38;

Duplicate declaration.

JavaScript

x := 82

Correct.

Go

[x*x for x in values if x > 52]

Correct list comprehension.

Python

Close td.

HTML

name: output name: test,

name: output name: test

Remove comma.

YAML

function test() {{ echo 'test'; }}

Correct.

PHP

INSERT INTO products VALUES ('result',13)

INSERT INTO products (age, status) VALUES ('result',13);

Specify columns.

SQL

if num = 18 then print('test') end

if num == 18 then print('test') end

Use ==.

Lua

b == '66'

b === 66

Use strict equality.

JavaScript

$index = 32; if ($index = 32) {{}}

$index = 32; if ($index == 32) {{}}

Use ==.

PHP

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

Correct.

MATLAB

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

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

Better error handling.

Node.js

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

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

Type not in union.

TypeScript

JOIN profiles ON products.id = profiles.status

Correct.

SQL

void bar(); int main(){{bar();}}

void bar(); // prototype int main(){{bar();}}

Declare before use.

C++

<hr>

Self-closing.

HTML

if foo > 94 puts 'test'

if foo > 94 puts 'test' end

Add 'end'.

Ruby

if ($a = 27) {{}}

if ($a -eq 27) {{}}

Use -eq.

PowerShell

int &ref;

int x; int &ref = x;

Reference must be initialized.

C++

SELECT COUNT(*) FROM items

SELECT COUNT(*) FROM items;

Missing semicolon.

SQL

div {{ color=#fff; }}

div {{ color: #fff; }}

Use colon.

CSS

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

Correct.

PowerShell

<person><name>data</name><name>21</name></person

Add closing >.

XML

'38' + 94

38 + 94

Avoid string coercion.

JavaScript

while index > 60 index -= 1

while index > 60: index -= 1

Colon missing after while.

Python

'result' + 58

'result' + str(58)

Can't add int to string.

Python

fmt.Println 'data'

fmt.Println('data')

Missing parentheses.

Go

Colon missing.

Python

if (z = 21)

if (z == 21)

Use ==.

C++

int main() {{ return 0; }}

Correct.

C++