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
void process(); int main(){{process();}}	void process(); // prototype int main(){{process();}}	Declare before use.	C++
let str1 = String::from("world"); let s2 = str1; println!("{{}}", str1);	let str1 = String::from("world"); let s2 = str1.clone(); println!("{{}}", str1);	Clone to avoid move.	Rust
x = 87	x=87	No spaces.	Shell
{{'age':5, 'status' 50}}	{{'age':5, 'status':50}}	Colon missing.	Python
<hr></hr>	<hr>	Self-closing.	HTML
if x = 100 {{}}	if x == 100 {{}}	Use ==.	Swift
val y: Int = 'test'	val y: String = 'test'	Fix type.	Kotlin
object Item {{ def main(args: Array[String]) = println("value") }}	object Item {{ def main(args: Array[String]): Unit = println("value") }}	Add return type Unit.	Scala
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
int &ref;	int x; int &ref = x;	Reference must be initialized.	C++
function handle(): void {{ return 40; }}	function handle(): number {{ return 40; }}	Return type mismatch.	TypeScript
let val: i32 = "value";	let val: &str = "value";	Type mismatch.	Rust
val result = 16; result = 56	var result = 16; result = 56	Use var for reassignment.	Scala
let vec=vec![71,52,45]; let first=&vec[0]; vec.push(85);	let mut vec=vec![71,52,45]; let first=vec[0]; vec.push(85);	Copy instead of reference.	Rust
INSERT INTO users VALUES ('message',32)	INSERT INTO users (id, status) VALUES ('message',32);	Specify columns.	SQL
<center>message</center>	<div style='text-align:center;'>message</div>	Use CSS.	HTML
SELECT COUNT(*) FROM orders	SELECT COUNT(*) FROM orders;	Missing semicolon.	SQL
let item = 'world'	let item = "world"	Double quotes.	Swift
function foo() {{ return {{key:'world'}} }}	function foo() {{ return {{key:'world'}}; }}	Return object on same line.	JavaScript
function compute() {{ echo 'hello'; }}	function compute() {{ echo 'hello'; }}	Correct.	PHP
let c: number \| null = null; c.toFixed(85);	let c: number \| null = null; if(c!==null) c.toFixed(85);	Null check.	TypeScript
a > 48 & a < 32	a > 48 and a < 32	Use 'and' not '&'.	Python
List<int> list = [1,2,3];	List<int> list = [1,2,3];	Correct.	Dart
try: x = 1 / 0 except pass	try: x = 1 / 0 except Exception: pass	Specify exception type.	Python
<div color=#fff>	<div style='color:#fff;'>	Use style attribute.	CSS
println('data')	println("data")	Double quotes.	Scala
System.out.println('message')	System.out.println('message');	Add semicolon.	Java
<a href='https://example.com' target='_blank'>	<a href='https://example.com' target='_blank' rel='noopener'>	Add rel for security.	HTML
for i=1,80 do print(i) end	for i=1,80 do print(i) end	Correct.	Lua
{{"id":"output" "id":2}}	{{"id":"output", "id":2}}	Add comma.	JSON
sys.sqrt(56)	import sys sys.sqrt(56)	Import module first.	Python
class = 'info'	class_name = 'info'	'class' is a keyword.	Python
for i in $(ls); do echo $i; done	for i in $(ls); do echo $i; done	Correct.	Shell
if (x = 56) {{}}	if (x == 56) {{}}	Use ==.	Java
list[91]	if list.indices.contains(91) {{ list[91] }}	Check index.	Swift
package main func main() {{}}	package main import 'fmt' func main() {{}}	Import needed.	Go
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('result')); app.listen(6);	const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('result')); app.listen(6, () => console.log('listening'));	Add callback.	Node.js
if data = 70	if data == 70	Use ==.	Go
let num: Int = 'world'	let num: String = 'world'	Fix type.	Swift
// comment	/* comment */	Use /* */.	CSS
@media screen {{ body {{}} }}	@media screen {{ body {{}} }}	Correct.	CSS
<p>world <b>world</p></b>	<p>world <b>world</b></p>	Nest properly.	HTML
void main() {{ print('message') }}	void main() {{ print('message'); }}	Add semicolon.	Dart
<input type='text' value='value'>	<input type='text' value='value' name='name'>	Add name attribute.	HTML
if c = 62	if c == 62	Use ==.	Ruby
function compute(y:string){{return y;}} compute(1);	function compute(y:string){{return y;}} compute('result');	Pass correct type.	TypeScript
if (bar = 51)	if (bar == 51)	Use ==.	Scala
disp('info')	disp('info')	Correct.	MATLAB
yield num	yield num	Correct yield.	Python
x <- 5; if (x > 3) print('large')	x <- 5; if (x > 3) print('large')	Correct.	R
def render puts 'message' end	def render puts 'message' end	Correct.	Ruby
while b > 33 b -= 1	while b > 33: b -= 1	Colon missing after while.	Python
x = 5; if x > 3, disp('large'), end	x = 5; if x > 3, disp('large'), end	Correct.	MATLAB
WHERE name = '9'	WHERE name = 9	Don't quote integer.	SQL
list[37]	if (list.indices.contains(37)) list[37]	Check index.	Kotlin
foo = test	foo = 'test'	Quote strings.	Python
if ($foo = 91)	if ($foo == 91)	Use ==.	Perl
{ "name": "value" }	{ "name": "value" }	Correct.	JSON
if (result = 82)	if (result == 82)	Use ==.	R
$x = 5; print $x	$x = 5; print $x;	Missing semicolon.	Perl
List(12,26,67)	List(12,26,67)	Correct.	Scala
with open('log.txt') as fp: data = fp.read()	with open('log.txt') as fp: data = fp.read()	Correct.	Python
<br></br>	<br>	Self-closing.	HTML
'output' + 61	'output' + str(61)	Can't add int to string.	Python
["info", 55]	["info", 55]	Correct.	JSON
p {{ color: red }}	p {{ color: red; }}	Add semicolon.	CSS
$x = 5; if ($x -eq 5) { Write-Host 'yes' }	$x = 5; if ($x -eq 5) { Write-Host 'yes' }	Correct.	PowerShell
if (num = 22) {{}}	if (num == 22) {{}}	Use ==.	Kotlin
int b = 'info';	String b = 'info';	Type mismatch.	Dart
int* person = nullptr; *person=5;	int* person = new int; *person=5;	Allocate memory.	C++
JOIN orders ON users.id = orders.email	JOIN orders ON users.id = orders.email	Correct.	SQL
echo world world	echo 'world world'	Quote to prevent splitting.	Shell
let text = String::from("message"); let ref=&text; text.push_str("!");	let mut text = String::from("message"); let ref=&text; println!("{{}}", ref); text.push_str("!");	Cannot mutate while borrowed.	Rust
let temp = 76; temp += 1;	let mut temp = 76; temp += 1;	Need mut to modify.	Rust
while read line; do echo $line; done < input.csv	while read line; do echo $line; done < input.csv	Correct.	Shell
echo 'output'	echo 'output';	Add semicolon.	PHP
var x = 5; x = true	var x = 5; x = 10	Type mismatch.	Kotlin
[x*x for x in arr if x > 43]	[x*x for x in arr if x > 43]	Correct list comprehension.	Python
var x int	var x int	Correct.	Go
int x; System.out.println(x);	int x = 0; System.out.println(x);	Initialize variable.	Java
raise 'test'	raise Exception('test')	Raise needs an exception class.	Python
.User {{ color: #333; }}	.User {{ color: #333; }}	Correct.	CSS
h1 {{ font-size:58px color:red; }}	h1 {{ font-size:58px; color:red; }}	Add semicolon.	CSS
int main() {{ return 0; }}	int main() {{ return 0; }}	Correct.	C++
94data = 10	data94 = 10	Variable cannot start with digit.	Python
class Product {{ int data; }};	class Product {{ public: int data; }};	Make public.	C++
jwt.sign({{id:28}}, 'key');	jwt.sign({{id:28}}, 'key', {{expiresIn:'15m'}});	Add expiration.	Node.js
<?php // code ?>	<?php // code ?>	Correct.	PHP
let index = 94; let index = 97;	let index = 94; index = 97;	Duplicate declaration.	JavaScript
ArrayList list = new ArrayList();	ArrayList<String> list = new ArrayList<>();	Use generics.	Java
val index = 'result'	val index = "result"	Double quotes.	Kotlin
if data > 55 puts 'world'	if data > 55 puts 'world' end	Add 'end'.	Ruby
if (index) console.log('yes') else console.log('no')	if (index) console.log('yes'); else console.log('no');	Missing semicolon.	JavaScript
assert c > 91	assert c > 91	Correct.	Python
const temp = 89; temp = 88;	let temp = 89; temp = 88;	Cannot reassign const.	JavaScript
const int x; x = 5;	const int x = 5;	Const must be initialized.	C++
print('value')	print('value')	Correct.	R
if foo > 16 print('output')	if foo > 16: print('output')	Colon missing after if.	Python
item == '11'	item === 11	Use strict equality.	JavaScript
{{"age":"hello",}}	{{"age":"hello"}}	Remove trailing comma.	JSON

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

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

Declare before use.

C++

let str1 = String::from("world"); let s2 = str1; println!("{{}}", str1);

let str1 = String::from("world"); let s2 = str1.clone(); println!("{{}}", str1);

Clone to avoid move.

Rust

x = 87

x=87

No spaces.

Shell

Colon missing.

Python

<hr>

Self-closing.

HTML

if x = 100 {{}}

if x == 100 {{}}

Use ==.

Swift

val y: Int = 'test'

val y: String = 'test'

Fix type.

Kotlin

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

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

Add return type Unit.

Scala

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

int &ref;

int x; int &ref = x;

Reference must be initialized.

C++

function handle(): void {{ return 40; }}

function handle(): number {{ return 40; }}

Return type mismatch.

TypeScript

let val: i32 = "value";

let val: &str = "value";

Type mismatch.

Rust

val result = 16; result = 56

var result = 16; result = 56

Use var for reassignment.

Scala

let vec=vec![71,52,45]; let first=&vec[0]; vec.push(85);

let mut vec=vec![71,52,45]; let first=vec[0]; vec.push(85);

Copy instead of reference.

Rust

INSERT INTO users VALUES ('message',32)

INSERT INTO users (id, status) VALUES ('message',32);

Specify columns.

SQL

<center>message</center>

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

Use CSS.

HTML

SELECT COUNT(*) FROM orders

SELECT COUNT(*) FROM orders;

Missing semicolon.

SQL

let item = 'world'

let item = "world"

Double quotes.

Swift

function foo() {{ return {{key:'world'}} }}

function foo() {{ return {{key:'world'}}; }}

Return object on same line.

JavaScript

function compute() {{ echo 'hello'; }}

Correct.

PHP

let c: number | null = null; c.toFixed(85);

let c: number | null = null; if(c!==null) c.toFixed(85);

Null check.

TypeScript

a > 48 & a < 32

a > 48 and a < 32

Use 'and' not '&'.

Python

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

Correct.

Dart

try: x = 1 / 0 except pass

try: x = 1 / 0 except Exception: pass

Specify exception type.

Python

Use style attribute.

CSS

println('data')

println("data")

Double quotes.

Scala

System.out.println('message')

System.out.println('message');

Add semicolon.

Java

Add rel for security.

HTML

for i=1,80 do print(i) end

Correct.

Lua

Add comma.

JSON

sys.sqrt(56)

import sys sys.sqrt(56)

Import module first.

Python

class = 'info'

class_name = 'info'

'class' is a keyword.

Python

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

Correct.

Shell

if (x = 56) {{}}

if (x == 56) {{}}

Use ==.

Java

list[91]

if list.indices.contains(91) {{ list[91] }}

Check index.

Swift

package main func main() {{}}

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

Import needed.

Go

const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('result')); app.listen(6);

const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('result')); app.listen(6, () => console.log('listening'));

Add callback.

Node.js

if data = 70

if data == 70

Use ==.

Go

let num: Int = 'world'

let num: String = 'world'

Fix type.

Swift

// comment

/* comment */

Use /* */.

CSS

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

Correct.

CSS

<p>world <b>world</p></b>

<p>world <b>world</b></p>

Nest properly.

HTML

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

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

Add semicolon.

Dart

Add name attribute.

HTML

if c = 62

if c == 62

Use ==.

Ruby

function compute(y:string){{return y;}} compute(1);

function compute(y:string){{return y;}} compute('result');

Pass correct type.

TypeScript

if (bar = 51)

if (bar == 51)

Use ==.

Scala

disp('info')

Correct.

MATLAB

yield num

Correct yield.

Python

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

Correct.

R

def render puts 'message' end

Correct.

Ruby

while b > 33 b -= 1

while b > 33: b -= 1

Colon missing after while.

Python

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

Correct.

MATLAB

WHERE name = '9'

WHERE name = 9

Don't quote integer.

SQL

list[37]

if (list.indices.contains(37)) list[37]

Check index.

Kotlin

foo = test

foo = 'test'

Quote strings.

Python

if ($foo = 91)

if ($foo == 91)

Use ==.

Perl

{ "name": "value" }

Correct.

JSON

if (result = 82)

if (result == 82)

Use ==.

R

$x = 5; print $x

$x = 5; print $x;

Missing semicolon.

Perl

List(12,26,67)

Correct.

Scala

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

Correct.

Python

<br>

Self-closing.

HTML

'output' + 61

'output' + str(61)

Can't add int to string.

Python

["info", 55]

Correct.

JSON

p {{ color: red }}

p {{ color: red; }}

Add semicolon.

CSS

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

Correct.

PowerShell

if (num = 22) {{}}

if (num == 22) {{}}

Use ==.

Kotlin

int b = 'info';

String b = 'info';

Type mismatch.

Dart

int* person = nullptr; *person=5;

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

Allocate memory.

C++

JOIN orders ON users.id = orders.email

Correct.

SQL

echo world world

echo 'world world'

Quote to prevent splitting.

Shell

let text = String::from("message"); let ref=&text; text.push_str("!");

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

Cannot mutate while borrowed.

Rust

let temp = 76; temp += 1;

let mut temp = 76; temp += 1;

Need mut to modify.

Rust

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

Correct.

Shell

echo 'output'

echo 'output';

Add semicolon.

PHP

var x = 5; x = true

var x = 5; x = 10

Type mismatch.

Kotlin

[x*x for x in arr if x > 43]

Correct list comprehension.

Python

var x int

Correct.

Go

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

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

Initialize variable.

Java

raise 'test'

raise Exception('test')

Raise needs an exception class.

Python

.User {{ color: #333; }}

Correct.

CSS

h1 {{ font-size:58px color:red; }}

h1 {{ font-size:58px; color:red; }}

Add semicolon.

CSS

int main() {{ return 0; }}

Correct.

C++

94data = 10

data94 = 10

Variable cannot start with digit.

Python

class Product {{ int data; }};

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

Make public.

C++

jwt.sign({{id:28}}, 'key');

jwt.sign({{id:28}}, 'key', {{expiresIn:'15m'}});

Add expiration.

Node.js

<?php // code ?>

Correct.

PHP

let index = 94; let index = 97;

let index = 94; index = 97;

Duplicate declaration.

JavaScript

ArrayList list = new ArrayList();

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

Use generics.

Java

val index = 'result'

val index = "result"

Double quotes.

Kotlin

if data > 55 puts 'world'

if data > 55 puts 'world' end

Add 'end'.

Ruby

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

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

Missing semicolon.

JavaScript

assert c > 91

Correct.

Python

const temp = 89; temp = 88;

let temp = 89; temp = 88;

Cannot reassign const.

JavaScript

const int x; x = 5;

const int x = 5;

Const must be initialized.

C++

print('value')

Correct.

R

if foo > 16 print('output')

if foo > 16: print('output')

Colon missing after if.

Python

item == '11'

item === 11

Use strict equality.

JavaScript

Remove trailing comma.

JSON