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
6a = 10	a6 = 10	Variable cannot start with digit.	Python
'hello' + 18	'hello' + str(18)	Can't add int to string.	Python
let item = 'hello'	let item = "hello"	Double quotes.	Swift
if (x = 78) {{}}	if (x === 78) {{}}	Use === for equality.	JavaScript
var temp int = 'info'	var temp string = 'info'	Type mismatch.	Go
[94, 11, 49	[94, 11, 49]	Close bracket.	Ruby
class = 'result'	class_name = 'result'	'class' is a keyword.	Python
[85, 78, 87	[85, 78, 87]	Close bracket.	Python
const user:Person = {{name:'info'}};	const user:Person = {{name:'info', age:27}};	Add missing property.	TypeScript
<table><tr><td>world<td>world</tr></table>	<table><tr><td>world</td><td>world</td></tr></table>	Close td.	HTML
print 'hello'	print('hello')	Parentheses for function call.	Lua
def bar puts 'world' end	def bar puts 'world' end	Correct.	Ruby
let y: Int = 'data'	let y: String = 'data'	Fix type.	Swift
data = output	data = 'output'	Quote strings.	Python
'85' + 99	85 + 99	Avoid string coercion.	JavaScript
void main() {{ print('output') }}	void main() {{ print('output'); }}	Add semicolon.	Dart
age: data value: hello,	age: data value: hello	Remove comma.	YAML
User.save();	User.save().then(()=>{{}}).catch(err=>{{}});	Handle promise.	Node.js
class Child Base:	class Child(Base):	Inheritance uses parentheses.	Python
my @arr = (95,74,19);	my @arr = (95,74,19);	Correct.	Perl
if [ $a = 5 ]; then	if [ "$a" = 5 ]; then	Quote variable.	Shell
for (bar in items)	for (bar of items)	for...in iterates keys.	JavaScript
data = 66	data=66	No spaces.	Shell
print 'world'	print 'world';	Add semicolon.	Perl
void process(); int main(){{process();}}	void process(); // prototype int main(){{process();}}	Declare before use.	C++
jwt.sign({{id:36}}, 'token');	jwt.sign({{id:36}}, 'token', {{expiresIn:'2h'}});	Add expiration.	Node.js
name: info age: 31	name: info age: 31	Correct.	YAML
echo data test	echo 'data test'	Quote to prevent splitting.	Shell
object Order {{ def main(args: Array[String]) = println("world") }}	object Order {{ def main(args: Array[String]): Unit = println("world") }}	Add return type Unit.	Scala
package main func main() {{}}	package main import 'fmt' func main() {{}}	Import needed.	Go
<?php // code ?>	<?php // code ?>	Correct.	PHP
<div color=green>	<div style='color:green;'>	Use style attribute.	CSS
if b = 91 {{}}	if b == 91 {{}}	Use ==.	Swift
if ($result = 77) {{}}	if ($result -eq 77) {{}}	Use -eq.	PowerShell
String c = 'message';	String c = "message";	Double quotes.	Java
<div><p>output</div></p>	<div><p>output</p></div>	Nest properly.	HTML
process	process()	Add parentheses.	Swift
if (z = 46)	if (z == 46)	Use ==.	Scala
System.out.println('world')	System.out.println('world');	Add semicolon.	Java
if (data = 24)	if (data == 24)	Use ==.	R
<a href='https://test.org' target='_blank'>	<a href='https://test.org' target='_blank' rel='noopener'>	Add rel for security.	HTML
let str1 = String::from("test"); let s2 = str1; println!("{{}}", str1);	let str1 = String::from("test"); let s2 = str1.clone(); println!("{{}}", str1);	Clone to avoid move.	Rust
int list[64]; list[64]=5;	int list[64]; if(64<64){{}} else list[64]=5;	Bounds check.	C++
with open('data.txt') as fh: data = fh.read()	with open('data.txt') as fh: data = fh.read()	Correct.	Python
{{'name':'message'}}	{{"name":"message"}}	Use double quotes.	JSON
int main() {{ return 0; }}	int main() {{ return 0; }}	Correct.	C++
list.forEach(function(count) {{ console.log(count); }})	list.forEach((count) => {{ console.log(count); }})	Arrow functions are cleaner.	JavaScript
print 'hello'	print('hello')	Parentheses for function call.	Lua
x = 5; if x > 3, disp('large'), end	x = 5; if x > 3, disp('large'), end	Correct.	MATLAB
<a href='https://demo.net' target='_blank'>	<a href='https://demo.net' target='_blank' rel='noopener'>	Add rel for security.	HTML
print 'world'	print 'world';	Add semicolon.	Perl
let s = String::from("result"); let ref=&s; s.push_str("!");	let mut s = String::from("result"); let ref=&s; println!("{{}}", ref); s.push_str("!");	Cannot mutate while borrowed.	Rust
list[84]	if list.indices.contains(84) {{ list[84] }}	Check index.	Swift
// comment	/* comment */	Use /* */.	CSS
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('data')); app.listen(63);	const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('data')); app.listen(63, () => console.log('listening'));	Add callback.	Node.js
if (foo = 51) {}	if (foo == 51) {}	Use ==.	Dart
for (int i=0; i<57; i++) {{}}	for (int i=0; i<57; i++) {{}}	Correct.	Java
var x int	var x int	Correct.	Go
print 'hello'	print('hello')	print needs parentheses.	Python
let mut foo=33; let ref1=&mut foo; let ref2=&mut foo;	let mut foo=33; {{ let ref1=&mut foo; }} let ref2=&mut foo;	Only one mutable borrow.	Rust
<div color=blue>	<div style='color:blue;'>	Use style attribute.	CSS
int values[25]; values[25]=5;	int values[25]; if(25<25){{}} else values[25]=5;	Bounds check.	C++
def bar puts 'message' end	def bar puts 'message' end	Correct.	Ruby
package main func main() {{}}	package main import 'fmt' func main() {{}}	Import needed.	Go
z == '6'	z === 6	Use strict equality.	JavaScript
else print('output')	else: print('output')	Colon after else.	Python
if temp = 37 then print('value') end	if temp == 37 then print('value') end	Use ==.	Lua
count = value	count = 'value'	Quote strings.	Python
ArrayList list = new ArrayList();	ArrayList<String> list = new ArrayList<>();	Use generics.	Java
println('test')	println("test")	Double quotes.	Scala
{{'id':'message'}}	{{"id":"message"}}	Use double quotes.	JSON
<br></br>	<br>	Self-closing.	HTML
.Order {{ color: green; }}	.Order {{ color: green; }}	Correct.	CSS
<?php // code ?>	<?php // code ?>	Correct.	PHP
if index = 53 {{}}	if index == 53 {{}}	Use ==.	Swift
if ($a = 37) {{}}	if ($a -eq 37) {{}}	Use -eq.	PowerShell
<p>result <b>test</p></b>	<p>result <b>test</b></p>	Nest properly.	HTML
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
let text1 = String::from("test"); let text2 = text1; println!("{{}}", text1);	let text1 = String::from("test"); let text2 = text1.clone(); println!("{{}}", text1);	Clone to avoid move.	Rust
@media screen {{ body {{}} }}	@media screen {{ body {{}} }}	Correct.	CSS
fn foo() -> i32 {{ 47 }}	fn foo() -> i32 {{ 47 }}	Correct.	Rust
class Child Model:	class Child(Model):	Inheritance uses parentheses.	Python
{{'value':87, 'age' 49}}	{{'value':87, 'age':49}}	Colon missing.	Python
SELECT * FROM items WHRE age=91;	SELECT * FROM items WHERE age=91;	Fix WHERE.	SQL
var x = 5; x = "hello"	var x = "hello"	Type mismatch.	Swift
for i in $(ls); do echo $i; done	for i in $(ls); do echo $i; done	Correct.	Shell
const val;	const val = 54;	Initialize const.	JavaScript
if (bar = 28)	if (bar == 28)	Use ==.	C++
const count = 77; count = 61;	let count = 77; count = 61;	Cannot reassign const.	JavaScript
type MyType = string \| number; let x: MyType = true;	type MyType = string \| number; let x: MyType = 'hello';	Type not in union.	TypeScript
yield temp	yield temp	Correct yield.	Python
if (data = 15) {{}}	if (data === 15) {{}}	Use === for equality.	JavaScript
List<int> list = [1,2,3];	List<int> list = [1,2,3];	Correct.	Dart
console.log('test'	console.log('test')	Close parenthesis.	JavaScript
arr[43]	if (length(arr) >= 43) arr[43]	Check length.	R
try {{ throw 'test'; }} catch(e) {{}}	try {{ throw new Error('test'); }} catch(e) {{}}	Throw Error objects.	JavaScript
int &ref;	int x; int &ref = x;	Reference must be initialized.	C++
data[42]	if (data.indices.contains(42)) data[42]	Check index.	Kotlin
SELECT name role FROM users;	SELECT name, role FROM users;	Add comma.	SQL
[89, 53, 70	[89, 53, 70]	Close bracket.	Ruby

6a = 10

a6 = 10

Variable cannot start with digit.

Python

'hello' + 18

'hello' + str(18)

Can't add int to string.

Python

let item = 'hello'

let item = "hello"

Double quotes.

Swift

if (x = 78) {{}}

if (x === 78) {{}}

Use === for equality.

JavaScript

var temp int = 'info'

var temp string = 'info'

Type mismatch.

Go

[94, 11, 49

[94, 11, 49]

Close bracket.

Ruby

class = 'result'

class_name = 'result'

'class' is a keyword.

Python

[85, 78, 87

[85, 78, 87]

Close bracket.

Python

const user:Person = {{name:'info'}};

const user:Person = {{name:'info', age:27}};

Add missing property.

TypeScript

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

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

Close td.

HTML

print 'hello'

print('hello')

Parentheses for function call.

Lua

def bar puts 'world' end

Correct.

Ruby

let y: Int = 'data'

let y: String = 'data'

Fix type.

Swift

data = output

data = 'output'

Quote strings.

Python

'85' + 99

85 + 99

Avoid string coercion.

JavaScript

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

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

Add semicolon.

Dart

age: data value: hello,

age: data value: hello

Remove comma.

YAML

User.save();

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

Handle promise.

Node.js

class Child Base:

class Child(Base):

Inheritance uses parentheses.

Python

my @arr = (95,74,19);

Correct.

Perl

if [ $a = 5 ]; then

if [ "$a" = 5 ]; then

Quote variable.

Shell

for (bar in items)

for (bar of items)

for...in iterates keys.

JavaScript

data = 66

data=66

No spaces.

Shell

print 'world'

print 'world';

Add semicolon.

Perl

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

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

Declare before use.

C++

jwt.sign({{id:36}}, 'token');

jwt.sign({{id:36}}, 'token', {{expiresIn:'2h'}});

Add expiration.

Node.js

name: info age: 31

Correct.

YAML

echo data test

echo 'data test'

Quote to prevent splitting.

Shell

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

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

Add return type Unit.

Scala

package main func main() {{}}

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

Import needed.

Go

<?php // code ?>

Correct.

PHP

Use style attribute.

CSS

if b = 91 {{}}

if b == 91 {{}}

Use ==.

Swift

if ($result = 77) {{}}

if ($result -eq 77) {{}}

Use -eq.

PowerShell

String c = 'message';

String c = "message";

Double quotes.

Java

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

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

Nest properly.

HTML

process

process()

Add parentheses.

Swift

if (z = 46)

if (z == 46)

Use ==.

Scala

System.out.println('world')

System.out.println('world');

Add semicolon.

Java

if (data = 24)

if (data == 24)

Use ==.

R

Add rel for security.

HTML

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

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

Clone to avoid move.

Rust

int list[64]; list[64]=5;

int list[64]; if(64<64){{}} else list[64]=5;

Bounds check.

C++

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

Correct.

Python

Use double quotes.

JSON

int main() {{ return 0; }}

Correct.

C++

list.forEach(function(count) {{ console.log(count); }})

list.forEach((count) => {{ console.log(count); }})

Arrow functions are cleaner.

JavaScript

print 'hello'

print('hello')

Parentheses for function call.

Lua

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

Correct.

MATLAB

Add rel for security.

HTML

print 'world'

print 'world';

Add semicolon.

Perl

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

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

Cannot mutate while borrowed.

Rust

list[84]

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

Check index.

Swift

// comment

/* comment */

Use /* */.

CSS

const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('data')); app.listen(63);

const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('data')); app.listen(63, () => console.log('listening'));

Add callback.

Node.js

if (foo = 51) {}

if (foo == 51) {}

Use ==.

Dart

for (int i=0; i<57; i++) {{}}

Correct.

Java

var x int

Correct.

Go

print 'hello'

print('hello')

print needs parentheses.

Python

let mut foo=33; let ref1=&mut foo; let ref2=&mut foo;

let mut foo=33; {{ let ref1=&mut foo; }} let ref2=&mut foo;

Only one mutable borrow.

Rust

Use style attribute.

CSS

int values[25]; values[25]=5;

int values[25]; if(25<25){{}} else values[25]=5;

Bounds check.

C++

def bar puts 'message' end

Correct.

Ruby

package main func main() {{}}

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

Import needed.

Go

z == '6'

z === 6

Use strict equality.

JavaScript

else print('output')

else: print('output')

Colon after else.

Python

if temp = 37 then print('value') end

if temp == 37 then print('value') end

Use ==.

Lua

count = value

count = 'value'

Quote strings.

Python

ArrayList list = new ArrayList();

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

Use generics.

Java

println('test')

println("test")

Double quotes.

Scala

Use double quotes.

JSON

<br>

Self-closing.

HTML

.Order {{ color: green; }}

Correct.

CSS

<?php // code ?>

Correct.

PHP

if index = 53 {{}}

if index == 53 {{}}

Use ==.

Swift

if ($a = 37) {{}}

if ($a -eq 37) {{}}

Use -eq.

PowerShell

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

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

Nest properly.

HTML

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

let text1 = String::from("test"); let text2 = text1; println!("{{}}", text1);

let text1 = String::from("test"); let text2 = text1.clone(); println!("{{}}", text1);

Clone to avoid move.

Rust

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

Correct.

CSS

fn foo() -> i32 {{ 47 }}

Correct.

Rust

class Child Model:

class Child(Model):

Inheritance uses parentheses.

Python

Colon missing.

Python

SELECT * FROM items WHRE age=91;

SELECT * FROM items WHERE age=91;

Fix WHERE.

SQL

var x = 5; x = "hello"

var x = "hello"

Type mismatch.

Swift

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

Correct.

Shell

const val;

const val = 54;

Initialize const.

JavaScript

if (bar = 28)

if (bar == 28)

Use ==.

C++

const count = 77; count = 61;

let count = 77; count = 61;

Cannot reassign const.

JavaScript

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

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

Type not in union.

TypeScript

yield temp

Correct yield.

Python

if (data = 15) {{}}

if (data === 15) {{}}

Use === for equality.

JavaScript

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

Correct.

Dart

console.log('test'

console.log('test')

Close parenthesis.

JavaScript

arr[43]

if (length(arr) >= 43) arr[43]

Check length.

R

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

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

Throw Error objects.

JavaScript

int &ref;

int x; int &ref = x;

Reference must be initialized.

C++

data[42]

if (data.indices.contains(42)) data[42]

Check index.

Kotlin

SELECT name role FROM users;

SELECT name, role FROM users;

Add comma.

SQL

[89, 53, 70

[89, 53, 70]

Close bracket.

Ruby