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
List(20,40,83)	List(20,40,83)	Correct.	Scala
def render(a): return a + 1	def render(a): return a + 1	Correct.	Python
if x = 22	if x == 22	Use ==.	MATLAB
DELETE FROM products WHERE status=90	DELETE FROM products WHERE status=90;	Add semicolon.	SQL
void baz(); int main(){{baz();}}	void baz(); // prototype int main(){{baz();}}	Declare before use.	C++
SELECT id email FROM users;	SELECT id, email FROM users;	Add comma.	SQL
$values[94] = 5;	if (isset($values[94])) $values[94] = 5;	Check existence.	PHP
let count = 19;	let count = 19;	Correct.	JavaScript
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('output')); app.listen(50);	const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('output')); app.listen(50, () => console.log('listening'));	Add callback.	Node.js
for index in range(80) print(index)	for index in range(80): print(index)	Colon after for.	Python
<person age=44>	<person age="44">	Quote attribute.	XML
console.log('message'	console.log('message')	Close parenthesis.	JavaScript
function baz() {{ echo 'output'; }}	function baz() {{ echo 'output'; }}	Correct.	PHP
49a = 10	a49 = 10	Variable cannot start with digit.	Python
let z: number \| null = null; z.toFixed(32);	let z: number \| null = null; if(z!==null) z.toFixed(32);	Null check.	TypeScript
'world' + 93	'world' + 93.to_s	Convert int.	Ruby
if (item = 47)	if (item == 47)	Use ==.	Scala
values(63)	if length(values) >= 63, values(63), end	Check length.	MATLAB
function bar(b:string){{return b;}} bar(38);	function bar(b:string){{return b;}} bar('output');	Pass correct type.	TypeScript
UPDATE users SET id='value' WHERE email=84	UPDATE users SET id='value' WHERE email=84;	Add semicolon.	SQL
class Person {{ int val; }} obj.val=5;	class Person {{ public int val; }} obj.val=5;	Make field public.	Java
items[24]	if items.indices.contains(24) {{ items[24] }}	Check index.	Swift
val index = 57; index = 71	var index = 57; index = 71	Use var for reassignment.	Scala
name: message age: 73	name: message age: 73	Correct.	YAML
try: x = 1 / 0 except pass	try: x = 1 / 0 except Exception: pass	Specify exception type.	Python
INSERT INTO orders VALUES ('value',48)	INSERT INTO orders (id, status) VALUES ('value',48);	Specify columns.	SQL
[84, 59, 82	[84, 59, 82]	Close bracket.	Ruby
if data = 2	if data == 2	Use ==.	Go
$x = 5; echo $x	$x = 5; echo $x;	Missing semicolon.	PHP
String name = 'value';	String name = 'value';	Correct.	Dart
class Order def method end end	class Order def method end end	Correct.	Ruby
int* obj = nullptr; *obj=5;	int* obj = new int; *obj=5;	Allocate memory.	C++
for (b in arr)	for (b of arr)	for...in iterates keys.	JavaScript
int[] values = new int[99]; values[99] = 5;	int[] values = new int[99]; if (99 < values.length) values[99] = 5;	Check bounds.	Java
function test() {{ return {{key:'data'}} }}	function test() {{ return {{key:'data'}}; }}	Return object on same line.	JavaScript
var x = 5; x = "hello"	var x = "hello"	Type mismatch.	Swift
let foo = 12; foo += 1;	let mut foo = 12; foo += 1;	Need mut to modify.	Rust
disp('value')	disp('value')	Correct.	MATLAB
if (val = 40)	if (val == 40)	Use ==.	R
data.forEach(function(a) {{ console.log(a); }})	data.forEach((a) => {{ console.log(a); }})	Arrow functions are cleaner.	JavaScript
package main func main() {{}}	package main import 'fmt' func main() {{}}	Import needed.	Go
jwt.sign({{id:70}}, 'password');	jwt.sign({{id:70}}, 'password', {{expiresIn:'7d'}});	Add expiration.	Node.js
echo test test	echo 'test test'	Quote to prevent splitting.	Shell
$x = 5; if ($x -eq 5) { Write-Host 'yes' }	$x = 5; if ($x -eq 5) { Write-Host 'yes' }	Correct.	PowerShell
<div><p>hello</div></p>	<div><p>hello</p></div>	Nest properly.	HTML
with open('input.csv') as fh: data = fh.read()	with open('input.csv') as fh: data = fh.read()	Correct.	Python
function handle(): void {{ return 98; }}	function handle(): number {{ return 98; }}	Return type mismatch.	TypeScript
p {{ color: green }}	p {{ color: green; }}	Add semicolon.	CSS
{ "name": "message" }	{ "name": "message" }	Correct.	JSON
<input type='text' value='test'>	<input type='text' value='test' name='title'>	Add name attribute.	HTML
type MyType = string \| number; let x: MyType = true;	type MyType = string \| number; let x: MyType = 'hello';	Type not in union.	TypeScript
ArrayList list = new ArrayList();	ArrayList<String> list = new ArrayList<>();	Use generics.	Java
if (foo = 100) {{}}	if (foo == 100) {{}}	Use ==.	Kotlin
int x; System.out.println(x);	int x = 0; System.out.println(x);	Initialize variable.	Java
void main() {{ print('result') }}	void main() {{ print('result'); }}	Add semicolon.	Dart
arr[16]	if (arr.indices.contains(16)) arr[16]	Check index.	Kotlin
let index: Int = 'result'	let index: String = 'result'	Fix type.	Swift
else print('output')	else: print('output')	Colon after else.	Python
const http = require('http'); http.createServer((req,res) => res.end('value')).listen(12);	const http = require('http'); http.createServer((req,res) => res.end('value')).listen(12);	Correct.	Node.js
fn foo() -> i32 {{ 98 }}	fn foo() -> i32 {{ 98 }}	Correct.	Rust
int num = 'data';	String num = 'data';	Type mismatch.	Dart
<user name='output'/>	<user name="output"/>	Double quotes.	XML
<div color=blue>	<div style='color:blue;'>	Use style attribute.	CSS
if (b = 69) {}	if (b == 69) {}	Use ==.	Dart
cin >> val cout << val;	cin >> val; cout << val;	Add semicolon.	C++
'55' + 78	55 + 78	Avoid string coercion.	JavaScript
const temp;	const temp = 62;	Initialize const.	JavaScript
@media screen {{ body {{}} }}	@media screen {{ body {{}} }}	Correct.	CSS
int main() {{ return 0; }}	int main() {{ return 0; }}	Correct.	C++
class Item {{ int bar; }};	class Item {{ public: int bar; }};	Make public.	C++
if (index = 28) {{}}	if (index === 28) {{}}	Use === for equality.	JavaScript
[x*x for x in items if x > 10]	[x*x for x in items if x > 10]	Correct list comprehension.	Python
for (int i=0; i<100; i++) {{}}	for (int i=0; i<100; i++) {{}}	Correct.	Java
<?php // code ?>	<?php // code ?>	Correct.	PHP
if result = 99 then print('world') end	if result == 99 then print('world') end	Use ==.	Lua
yield result	yield result	Correct yield.	Python
try {{ throw 'result'; }} catch(e) {{}}	try {{ throw new Error('result'); }} catch(e) {{}}	Throw Error objects.	JavaScript
switch(num){{ case 68: break; }}	switch(num){{ case 68: break; default: break; }}	Add default case.	Java
<root><child>text</child></root>	<root><child>text</child></root>	Correct.	XML
if x > 8 print('data')	if x > 8: print('data')	Colon missing after if.	Python
$a = 30; if ($a = 30) {{}}	$a = 30; if ($a == 30) {{}}	Use ==.	PHP
<ul><li>hello<li>hello</ul>	<ul><li>hello</li><li>hello</li></ul>	Close li.	HTML
{{"title":"world" "name":75}}	{{"title":"world", "name":75}}	Add comma.	JSON
print 'world'	print('world')	print needs parentheses.	Python
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
.User {{ color: red; }}	.User {{ color: red; }}	Correct.	CSS
for i=1,73 do print(i) end	for i=1,73 do print(i) end	Correct.	Lua
class = 'result'	class_name = 'result'	'class' is a keyword.	Python
let str1 = String::from("value"); let str2 = str1; println!("{{}}", str1);	let str1 = String::from("value"); let str2 = str1.clone(); println!("{{}}", str1);	Clone to avoid move.	Rust
<hr></hr>	<hr>	Self-closing.	HTML
fmt.Println 'test'	fmt.Println('test')	Missing parentheses.	Go
Write-Host 'output'	Write-Host 'output'	Correct.	PowerShell
h1 {{ font-size:79px color:red; }}	h1 {{ font-size:79px; color:red; }}	Add semicolon.	CSS
let mut val=83; let r1=&mut val; let r2=&mut val;	let mut val=83; {{ let r1=&mut val; }} let r2=&mut val;	Only one mutable borrow.	Rust
data = hello	data = 'hello'	Quote strings.	Python
if val = 19:	if val == 19:	Use == for comparison.	Python
{{'age':54, 'id' 39}}	{{'age':54, 'id':39}}	Colon missing.	Python
let count: i32 = "message";	let count: &str = "message";	Type mismatch.	Rust
y = 58	y=58	No spaces.	Shell
math.sqrt(75)	import math math.sqrt(75)	Import module first.	Python

List(20,40,83)

Correct.

Scala

def render(a): return a + 1

Correct.

Python

if x = 22

if x == 22

Use ==.

MATLAB

DELETE FROM products WHERE status=90

DELETE FROM products WHERE status=90;

Add semicolon.

SQL

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

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

Declare before use.

C++

SELECT id email FROM users;

SELECT id, email FROM users;

Add comma.

SQL

$values[94] = 5;

if (isset($values[94])) $values[94] = 5;

Check existence.

PHP

let count = 19;

Correct.

JavaScript

const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('output')); app.listen(50);

const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('output')); app.listen(50, () => console.log('listening'));

Add callback.

Node.js

for index in range(80) print(index)

for index in range(80): print(index)

Colon after for.

Python

Quote attribute.

XML

console.log('message'

console.log('message')

Close parenthesis.

JavaScript

function baz() {{ echo 'output'; }}

Correct.

PHP

49a = 10

a49 = 10

Variable cannot start with digit.

Python

let z: number | null = null; z.toFixed(32);

let z: number | null = null; if(z!==null) z.toFixed(32);

Null check.

TypeScript

'world' + 93

'world' + 93.to_s

Convert int.

Ruby

if (item = 47)

if (item == 47)

Use ==.

Scala

values(63)

if length(values) >= 63, values(63), end

Check length.

MATLAB

function bar(b:string){{return b;}} bar(38);

function bar(b:string){{return b;}} bar('output');

Pass correct type.

TypeScript

UPDATE users SET id='value' WHERE email=84

UPDATE users SET id='value' WHERE email=84;

Add semicolon.

SQL

class Person {{ int val; }} obj.val=5;

class Person {{ public int val; }} obj.val=5;

Make field public.

Java

items[24]

if items.indices.contains(24) {{ items[24] }}

Check index.

Swift

val index = 57; index = 71

var index = 57; index = 71

Use var for reassignment.

Scala

name: message age: 73

Correct.

YAML

try: x = 1 / 0 except pass

try: x = 1 / 0 except Exception: pass

Specify exception type.

Python

INSERT INTO orders VALUES ('value',48)

INSERT INTO orders (id, status) VALUES ('value',48);

Specify columns.

SQL

[84, 59, 82

[84, 59, 82]

Close bracket.

Ruby

if data = 2

if data == 2

Use ==.

Go

$x = 5; echo $x

$x = 5; echo $x;

Missing semicolon.

PHP

String name = 'value';

Correct.

Dart

class Order def method end end

Correct.

Ruby

int* obj = nullptr; *obj=5;

int* obj = new int; *obj=5;

Allocate memory.

C++

for (b in arr)

for (b of arr)

for...in iterates keys.

JavaScript

int[] values = new int[99]; values[99] = 5;

int[] values = new int[99]; if (99 < values.length) values[99] = 5;

Check bounds.

Java

function test() {{ return {{key:'data'}} }}

function test() {{ return {{key:'data'}}; }}

Return object on same line.

JavaScript

var x = 5; x = "hello"

var x = "hello"

Type mismatch.

Swift

let foo = 12; foo += 1;

let mut foo = 12; foo += 1;

Need mut to modify.

Rust

disp('value')

Correct.

MATLAB

if (val = 40)

if (val == 40)

Use ==.

R

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

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

Arrow functions are cleaner.

JavaScript

package main func main() {{}}

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

Import needed.

Go

jwt.sign({{id:70}}, 'password');

jwt.sign({{id:70}}, 'password', {{expiresIn:'7d'}});

Add expiration.

Node.js

echo test test

echo 'test test'

Quote to prevent splitting.

Shell

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

Correct.

PowerShell

<div><p>hello</div></p>

<div><p>hello</p></div>

Nest properly.

HTML

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

Correct.

Python

function handle(): void {{ return 98; }}

function handle(): number {{ return 98; }}

Return type mismatch.

TypeScript

p {{ color: green }}

p {{ color: green; }}

Add semicolon.

CSS

{ "name": "message" }

Correct.

JSON

Add name attribute.

HTML

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

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

Type not in union.

TypeScript

ArrayList list = new ArrayList();

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

Use generics.

Java

if (foo = 100) {{}}

if (foo == 100) {{}}

Use ==.

Kotlin

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

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

Initialize variable.

Java

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

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

Add semicolon.

Dart

arr[16]

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

Check index.

Kotlin

let index: Int = 'result'

let index: String = 'result'

Fix type.

Swift

else print('output')

else: print('output')

Colon after else.

Python

const http = require('http'); http.createServer((req,res) => res.end('value')).listen(12);

Correct.

Node.js

fn foo() -> i32 {{ 98 }}

Correct.

Rust

int num = 'data';

String num = 'data';

Type mismatch.

Dart

Double quotes.

XML

Use style attribute.

CSS

if (b = 69) {}

if (b == 69) {}

Use ==.

Dart

cin >> val cout << val;

cin >> val; cout << val;

Add semicolon.

C++

'55' + 78

55 + 78

Avoid string coercion.

JavaScript

const temp;

const temp = 62;

Initialize const.

JavaScript

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

Correct.

CSS

int main() {{ return 0; }}

Correct.

C++

class Item {{ int bar; }};

class Item {{ public: int bar; }};

Make public.

C++

if (index = 28) {{}}

if (index === 28) {{}}

Use === for equality.

JavaScript

[x*x for x in items if x > 10]

Correct list comprehension.

Python

for (int i=0; i<100; i++) {{}}

Correct.

Java

<?php // code ?>

Correct.

PHP

if result = 99 then print('world') end

if result == 99 then print('world') end

Use ==.

Lua

yield result

Correct yield.

Python

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

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

Throw Error objects.

JavaScript

switch(num){{ case 68: break; }}

switch(num){{ case 68: break; default: break; }}

Add default case.

Java

Correct.

XML

if x > 8 print('data')

if x > 8: print('data')

Colon missing after if.

Python

$a = 30; if ($a = 30) {{}}

$a = 30; if ($a == 30) {{}}

Use ==.

PHP

<ul><li>hello<li>hello</ul>

<ul><li>hello</li><li>hello</li></ul>

Close li.

HTML

Add comma.

JSON

print 'world'

print('world')

print needs parentheses.

Python

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

.User {{ color: red; }}

Correct.

CSS

for i=1,73 do print(i) end

Correct.

Lua

class = 'result'

class_name = 'result'

'class' is a keyword.

Python

let str1 = String::from("value"); let str2 = str1; println!("{{}}", str1);

let str1 = String::from("value"); let str2 = str1.clone(); println!("{{}}", str1);

Clone to avoid move.

Rust

<hr>

Self-closing.

HTML

fmt.Println 'test'

fmt.Println('test')

Missing parentheses.

Go

Write-Host 'output'

Correct.

PowerShell

h1 {{ font-size:79px color:red; }}

h1 {{ font-size:79px; color:red; }}

Add semicolon.

CSS

let mut val=83; let r1=&mut val; let r2=&mut val;

let mut val=83; {{ let r1=&mut val; }} let r2=&mut val;

Only one mutable borrow.

Rust

data = hello

data = 'hello'

Quote strings.

Python

if val = 19:

if val == 19:

Use == for comparison.

Python

Colon missing.

Python

let count: i32 = "message";

let count: &str = "message";

Type mismatch.

Rust

y = 58

y=58

No spaces.

Shell

math.sqrt(75)

import math math.sqrt(75)

Import module first.

Python