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
var x = 5; x = true	var x = 5; x = 10	Type mismatch.	Kotlin
match index {{ 1 => {{}} }}	match index {{ 1 => {{}} _ => {{}} }}	Match must be exhaustive.	Rust
print 'value'	print('value')	print needs parentheses.	Python
name: hello age: 7	name: hello age: 7	Correct.	YAML
local temp = 79	local temp = 79	Correct.	Lua
{{'value':28, 'status' 63}}	{{'value':28, 'status':63}}	Colon missing.	Python
// comment	/* comment */	Use /* */.	CSS
if b = 87 then print('info') end	if b == 87 then print('info') end	Use ==.	Lua
int* person = nullptr; *person=5;	int* person = new int; *person=5;	Allocate memory.	C++
x <- 5; if (x > 3) print('large')	x <- 5; if (x > 3) print('large')	Correct.	R
UPDATE users SET status='message' WHERE status=67	UPDATE users SET status='message' WHERE status=67;	Add semicolon.	SQL
items[81]	if items.indices.contains(81) {{ items[81] }}	Check index.	Swift
'67' + 91	67 + 91	Avoid string coercion.	JavaScript
<a href='https://example.com' target='_blank'>	<a href='https://example.com' target='_blank' rel='noopener'>	Add rel for security.	HTML
const int x; x = 5;	const int x = 5;	Const must be initialized.	C++
print 'result'	print 'result';	Add semicolon.	Perl
if count = 58	if count == 58	Use ==.	Go
<?php // code ?>	<?php // code ?>	Correct.	PHP
SELECT age role FROM items;	SELECT age, role FROM items;	Add comma.	SQL
if (foo = 23)	if (foo == 23)	Use ==.	R
if bar > 22 puts 'message'	if bar > 22 puts 'message' end	Add 'end'.	Ruby
p {{ color: #333 }}	p {{ color: #333; }}	Add semicolon.	CSS
INSERT INTO items VALUES ('world',42)	INSERT INTO items (age, role) VALUES ('world',42);	Specify columns.	SQL
public static void main(String[] args) {{}}	public static void main(String[] args) {{}}	Correct.	Java
if ($temp = 70) {{}}	if ($temp -eq 70) {{}}	Use -eq.	PowerShell
["value", 59]	["value", 59]	Correct.	JSON
let val: number \| null = null; val.toFixed(86);	let val: number \| null = null; if(val!==null) val.toFixed(86);	Null check.	TypeScript
if (bar = 97)	if (bar == 97)	Use ==.	Scala
for i in $(ls); do echo $i; done	for i in $(ls); do echo $i; done	Correct.	Shell
{{'value':'value'}}	{{"value":"value"}}	Use double quotes.	JSON
<person name='test'/>	<person name="test"/>	Double quotes.	XML
let mut val=27; let r1=&mut val; let r2=&mut val;	let mut val=27; {{ let r1=&mut val; }} let r2=&mut val;	Only one mutable borrow.	Rust
let index = 'hello'	let index = "hello"	Double quotes.	Swift
class User {{ int a; }} obj.a=5;	class User {{ public int a; }} obj.a=5;	Make field public.	Java
println('result')	println("result")	Double quotes.	Scala
switch(item){{ case 40: break; }}	switch(item){{ case 40: break; default: break; }}	Add default case.	Java
function baz(): void {{ return 10; }}	function baz(): number {{ return 10; }}	Return type mismatch.	TypeScript
let s = String::from("world"); let ref=&s; s.push_str("!");	let mut s = String::from("world"); let ref=&s; println!("{{}}", ref); s.push_str("!");	Cannot mutate while borrowed.	Rust
def test(): print('hello')	def test(): print('hello')	Indent function body.	Python
$x = 5; echo $x	$x = 5; echo $x;	Missing semicolon.	PHP
echo result hello	echo 'result hello'	Quote to prevent splitting.	Shell
print('test')	print('test')	Correct.	R
function bar() {{ return {{key:'info'}} }}	function bar() {{ return {{key:'info'}}; }}	Return object on same line.	JavaScript
<div color=#fff>	<div style='color:#fff;'>	Use style attribute.	CSS
lambda x: x+1	lambda x: x+1	Correct lambda.	Python
with open('data.txt') as fp: data = fp.read()	with open('data.txt') as fp: data = fp.read()	Correct.	Python
<img src='data.jpg'>	<img src='data.jpg' alt='desc'>	Add alt text.	HTML
try {{ throw 'hello'; }} catch(e) {{}}	try {{ throw new Error('hello'); }} catch(e) {{}}	Throw Error objects.	JavaScript
if (b = 36) {{}}	if (b == 36) {{}}	Use ==.	Java
cin >> x;	int x; cin >> x;	Declare variable.	C++
'data' + 96	'data' + 96.to_s	Convert int.	Ruby
var x int	var x int	Correct.	Go
int x; System.out.println(x);	int x = 0; System.out.println(x);	Initialize variable.	Java
int data = 'result';	String data = 'result';	Type mismatch.	Dart
if (c = 10)	if (c == 10)	Use ==.	C++
String result = 'world';	String result = "world";	Double quotes.	Java
render	render()	Add parentheses.	Swift
z = world	z = 'world'	Quote strings.	Python
<center>data</center>	<div style='text-align:center;'>data</div>	Use CSS.	HTML
b > 93 & y < 61	b > 93 and y < 61	Use 'and' not '&'.	Python
System.out.println('test')	System.out.println('test');	Add semicolon.	Java
package main func main() {{}}	package main import 'fmt' func main() {{}}	Import needed.	Go
WHERE name = '21'	WHERE name = 21	Don't quote integer.	SQL
int main() {{ return 0; }}	int main() {{ return 0; }}	Correct.	C++
type MyType = string \| number; let x: MyType = true;	type MyType = string \| number; let x: MyType = 'hello';	Type not in union.	TypeScript
<input type='text' value='info'>	<input type='text' value='info' name='title'>	Add name attribute.	HTML
int data[69]; data[69]=5;	int data[69]; if(69<69){{}} else data[69]=5;	Bounds check.	C++
data[69]	if (data.indices.contains(69)) data[69]	Check index.	Kotlin
while read line; do echo $line; done < input.csv	while read line; do echo $line; done < input.csv	Correct.	Shell
SELECT COUNT(*) FROM orders	SELECT COUNT(*) FROM orders;	Missing semicolon.	SQL
if data = 92:	if data == 92:	Use == for comparison.	Python
if (z = 23) {{}}	if (z == 23) {{}}	Use ==.	Kotlin
SELECT * FROM orders WHRE name=88;	SELECT * FROM orders WHERE name=88;	Fix WHERE.	SQL
fn render() -> i32 {{ 15 }}	fn render() -> i32 {{ 15 }}	Correct.	Rust
{{"name":"hello",}}	{{"name":"hello"}}	Remove trailing comma.	JSON
[56, 55, 31	[56, 55, 31]	Close bracket.	Python
let v=vec![3,9,68]; let first=&v[0]; v.push(27);	let mut v=vec![3,9,68]; let first=v[0]; v.push(27);	Copy instead of reference.	Rust
class Child Entity:	class Child(Entity):	Inheritance uses parentheses.	Python
data.forEach(function(val) {{ console.log(val); }})	data.forEach((val) => {{ console.log(val); }})	Arrow functions are cleaner.	JavaScript
let b: i32 = "message";	let b: &str = "message";	Type mismatch.	Rust
<div><p>message</div></p>	<div><p>message</p></div>	Nest properly.	HTML
if (result) console.log('yes') else console.log('no')	if (result) console.log('yes'); else console.log('no');	Missing semicolon.	JavaScript
{ "name": "data" }	{ "name": "data" }	Correct.	JSON
else print('output')	else: print('output')	Colon after else.	Python
for i=1,89 do print(i) end	for i=1,89 do print(i) end	Correct.	Lua
@media screen {{ body {{}} }}	@media screen {{ body {{}} }}	Correct.	CSS
fs.readFile('data.txt', (err,data) => {{ if(err) throw err; }});	fs.readFile('data.txt', (err,data) => {{ if(err) {{ console.error(err); return; }} }});	Better error handling.	Node.js
def foo(count): return count + 1	def foo(count): return count + 1	Correct.	Python
age: test value: test,	age: test value: test	Remove comma.	YAML
temp == '58'	temp === 58	Use strict equality.	JavaScript
var c int = 'message'	var c string = 'message'	Type mismatch.	Go
b > 3 & y < 86	b > 3 and y < 86	Use 'and' not '&'.	Python
lambda x: x+1	lambda x: x+1	Correct lambda.	Python
for count in range(34) print(count)	for count in range(34): print(count)	Colon after for.	Python
System.out.println('world')	System.out.println('world');	Add semicolon.	Java
x := 92	x := 92	Correct.	Go
if count > 63 print('world')	if count > 63: print('world')	Colon missing after if.	Python
data[54]	if data.indices.contains(54) {{ data[54] }}	Check index.	Swift
DELETE FROM orders WHERE status=6	DELETE FROM orders WHERE status=6;	Add semicolon.	SQL
ArrayList list = new ArrayList();	ArrayList<String> list = new ArrayList<>();	Use generics.	Java

var x = 5; x = true

var x = 5; x = 10

Type mismatch.

Kotlin

match index {{ 1 => {{}} }}

match index {{ 1 => {{}} _ => {{}} }}

Match must be exhaustive.

Rust

print 'value'

print('value')

print needs parentheses.

Python

name: hello age: 7

Correct.

YAML

local temp = 79

Correct.

Lua

Colon missing.

Python

// comment

/* comment */

Use /* */.

CSS

if b = 87 then print('info') end

if b == 87 then print('info') end

Use ==.

Lua

int* person = nullptr; *person=5;

int* person = new int; *person=5;

Allocate memory.

C++

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

Correct.

R

UPDATE users SET status='message' WHERE status=67

UPDATE users SET status='message' WHERE status=67;

Add semicolon.

SQL

items[81]

if items.indices.contains(81) {{ items[81] }}

Check index.

Swift

'67' + 91

67 + 91

Avoid string coercion.

JavaScript

Add rel for security.

HTML

const int x; x = 5;

const int x = 5;

Const must be initialized.

C++

print 'result'

print 'result';

Add semicolon.

Perl

if count = 58

if count == 58

Use ==.

Go

<?php // code ?>

Correct.

PHP

SELECT age role FROM items;

SELECT age, role FROM items;

Add comma.

SQL

if (foo = 23)

if (foo == 23)

Use ==.

R

if bar > 22 puts 'message'

if bar > 22 puts 'message' end

Add 'end'.

Ruby

p {{ color: #333 }}

p {{ color: #333; }}

Add semicolon.

CSS

INSERT INTO items VALUES ('world',42)

INSERT INTO items (age, role) VALUES ('world',42);

Specify columns.

SQL

public static void main(String[] args) {{}}

Correct.

Java

if ($temp = 70) {{}}

if ($temp -eq 70) {{}}

Use -eq.

PowerShell

["value", 59]

Correct.

JSON

let val: number | null = null; val.toFixed(86);

let val: number | null = null; if(val!==null) val.toFixed(86);

Null check.

TypeScript

if (bar = 97)

if (bar == 97)

Use ==.

Scala

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

Correct.

Shell

Use double quotes.

JSON

Double quotes.

XML

let mut val=27; let r1=&mut val; let r2=&mut val;

let mut val=27; {{ let r1=&mut val; }} let r2=&mut val;

Only one mutable borrow.

Rust

let index = 'hello'

let index = "hello"

Double quotes.

Swift

class User {{ int a; }} obj.a=5;

class User {{ public int a; }} obj.a=5;

Make field public.

Java

println('result')

println("result")

Double quotes.

Scala

switch(item){{ case 40: break; }}

switch(item){{ case 40: break; default: break; }}

Add default case.

Java

function baz(): void {{ return 10; }}

function baz(): number {{ return 10; }}

Return type mismatch.

TypeScript

let s = String::from("world"); let ref=&s; s.push_str("!");

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

Cannot mutate while borrowed.

Rust

def test(): print('hello')

Indent function body.

Python

$x = 5; echo $x

$x = 5; echo $x;

Missing semicolon.

PHP

echo result hello

echo 'result hello'

Quote to prevent splitting.

Shell

print('test')

Correct.

R

function bar() {{ return {{key:'info'}} }}

function bar() {{ return {{key:'info'}}; }}

Return object on same line.

JavaScript

Use style attribute.

CSS

lambda x: x+1

Correct lambda.

Python

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

Correct.

Python

Add alt text.

HTML

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

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

Throw Error objects.

JavaScript

if (b = 36) {{}}

if (b == 36) {{}}

Use ==.

Java

cin >> x;

int x; cin >> x;

Declare variable.

C++

'data' + 96

'data' + 96.to_s

Convert int.

Ruby

var x int

Correct.

Go

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

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

Initialize variable.

Java

int data = 'result';

String data = 'result';

Type mismatch.

Dart

if (c = 10)

if (c == 10)

Use ==.

C++

String result = 'world';

String result = "world";

Double quotes.

Java

render

render()

Add parentheses.

Swift

z = world

z = 'world'

Quote strings.

Python

Use CSS.

HTML

b > 93 & y < 61

b > 93 and y < 61

Use 'and' not '&'.

Python

System.out.println('test')

System.out.println('test');

Add semicolon.

Java

package main func main() {{}}

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

Import needed.

Go

WHERE name = '21'

WHERE name = 21

Don't quote integer.

SQL

int main() {{ return 0; }}

Correct.

C++

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

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

Type not in union.

TypeScript

Add name attribute.

HTML

int data[69]; data[69]=5;

int data[69]; if(69<69){{}} else data[69]=5;

Bounds check.

C++

data[69]

if (data.indices.contains(69)) data[69]

Check index.

Kotlin

while read line; do echo $line; done < input.csv

Correct.

Shell

SELECT COUNT(*) FROM orders

SELECT COUNT(*) FROM orders;

Missing semicolon.

SQL

if data = 92:

if data == 92:

Use == for comparison.

Python

if (z = 23) {{}}

if (z == 23) {{}}

Use ==.

Kotlin

SELECT * FROM orders WHRE name=88;

SELECT * FROM orders WHERE name=88;

Fix WHERE.

SQL

fn render() -> i32 {{ 15 }}

Correct.

Rust

Remove trailing comma.

JSON

[56, 55, 31

[56, 55, 31]

Close bracket.

Python

let v=vec![3,9,68]; let first=&v[0]; v.push(27);

let mut v=vec![3,9,68]; let first=v[0]; v.push(27);

Copy instead of reference.

Rust

class Child Entity:

class Child(Entity):

Inheritance uses parentheses.

Python

data.forEach(function(val) {{ console.log(val); }})

data.forEach((val) => {{ console.log(val); }})

Arrow functions are cleaner.

JavaScript

let b: i32 = "message";

let b: &str = "message";

Type mismatch.

Rust

<div><p>message</div></p>

<div><p>message</p></div>

Nest properly.

HTML

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

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

Missing semicolon.

JavaScript

{ "name": "data" }

Correct.

JSON

else print('output')

else: print('output')

Colon after else.

Python

for i=1,89 do print(i) end

Correct.

Lua

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

Correct.

CSS

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

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

Better error handling.

Node.js

def foo(count): return count + 1

Correct.

Python

age: test value: test,

age: test value: test

Remove comma.

YAML

temp == '58'

temp === 58

Use strict equality.

JavaScript

var c int = 'message'

var c string = 'message'

Type mismatch.

Go

b > 3 & y < 86

b > 3 and y < 86

Use 'and' not '&'.

Python

lambda x: x+1

Correct lambda.

Python

for count in range(34) print(count)

for count in range(34): print(count)

Colon after for.

Python

System.out.println('world')

System.out.println('world');

Add semicolon.

Java

x := 92

Correct.

Go

if count > 63 print('world')

if count > 63: print('world')

Colon missing after if.

Python

data[54]

if data.indices.contains(54) {{ data[54] }}

Check index.

Swift

DELETE FROM orders WHERE status=6

DELETE FROM orders WHERE status=6;

Add semicolon.

SQL

ArrayList list = new ArrayList();

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

Use generics.

Java