wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 83
values | language stringclasses 23
values |
|---|---|---|---|
p {{ color: green }} | p {{ color: green; }} | Add semicolon. | CSS |
int[] items = new int[27];
items[27] = 5; | int[] items = new int[27];
if (27 < items.length) items[27] = 5; | Check bounds. | Java |
if bar = 15 {{}} | if bar == 15 {{}} | Use ==. | Swift |
if (bar = 53) {{}} | if (bar == 53) {{}} | Use ==. | Java |
if (y = 50) {{}} | if (y === 50) {{}} | Use === for equality. | JavaScript |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
if b = 48: | if b == 48: | Use == for comparison. | Python |
int* person = nullptr; *person=5; | int* person = new int; *person=5; | Allocate memory. | C++ |
data(60) | if length(data) >= 60, data(60), end | Check length. | MATLAB |
def test
puts 'test'
end | def test
puts 'test'
end | Correct. | Ruby |
try {{ throw 'world'; }} catch(e) {{}} | try {{ throw new Error('world'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
values.forEach(function(num) {{ console.log(num); }}) | values.forEach((num) => {{ console.log(num); }}) | Arrow functions are cleaner. | JavaScript |
for (int i=0; i<2; i++) {{}} | for (int i=0; i<2; i++) {{}} | Correct. | Java |
if (a = 23) {{}} | if (a === 23) {{}} | Use === for equality. | JavaScript |
if z = 95: | if z == 95: | Use == for comparison. | Python |
Product.save(); | Product.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
let text = String::from("result"); let ref=&text; text.push_str("!"); | let mut text = String::from("result"); let ref=&text; println!("{{}}", ref); text.push_str("!"); | Cannot mutate while borrowed. | Rust |
<div><p>info</div></p> | <div><p>info</p></div> | Nest properly. | HTML |
#footer {{ color: green; }} | #footer {{ color: green; }} | Correct. | CSS |
if data = 88 | if data == 88 | Use ==. | MATLAB |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
z == '48' | z === 48 | Use strict equality. | JavaScript |
val item = 'test' | val item = "test" | Double quotes. | Kotlin |
if result = 14 | if result == 14 | Use ==. | Go |
echo 'result' | echo 'result'; | Add semicolon. | PHP |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
const user:Person = {{name:'world'}}; | const user:Person = {{name:'world', age:9}}; | Add missing property. | TypeScript |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
my @arr = (21,48,13); | my @arr = (21,48,13); | Correct. | Perl |
<hr></hr> | <hr> | Self-closing. | HTML |
fn render() -> i32 {{ 77 }} | fn render() -> i32 {{ 77 }} | Correct. | Rust |
INSERT INTO items VALUES ('data',8) | INSERT INTO items (id, status) VALUES ('data',8); | Specify columns. | SQL |
class = 'data' | class_name = 'data' | 'class' is a keyword. | Python |
if ($item = 54) | if ($item == 54) | Use ==. | Perl |
let mut val=32; let r1=&mut val; let r2=&mut val; | let mut val=32; {{ let r1=&mut val; }} let r2=&mut val; | Only one mutable borrow. | Rust |
int values[10]; values[10]=5; | int values[10]; if(10<10){{}} else values[10]=5; | Bounds check. | C++ |
<note name='data'/> | <note name="data"/> | Double quotes. | XML |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
class User {{ int foo; }}; | class User {{ public: int foo; }}; | Make public. | C++ |
{{"id":"test" "status":63}} | {{"id":"test", "status":63}} | Add comma. | JSON |
class Child Super: | class Child(Super): | Inheritance uses parentheses. | Python |
if (result = 3) {{}} | if (result == 3) {{}} | Use ==. | Kotlin |
for (count in items) | for (count of items) | for...in iterates keys. | JavaScript |
let str1 = String::from("output"); let str2 = str1; println!("{{}}", str1); | let str1 = String::from("output"); let str2 = str1.clone(); println!("{{}}", str1); | Clone to avoid move. | Rust |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
SELECT * FROM items WHRE id=11; | SELECT * FROM items WHERE id=11; | Fix WHERE. | SQL |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
String count = 'hello'; | String count = "hello"; | Double quotes. | Java |
list.forEach(function(count) {{ console.log(count); }}) | list.forEach((count) => {{ console.log(count); }}) | Arrow functions are cleaner. | JavaScript |
fs.readFile('config.json', (err,data) => {{ if(err) throw err; }}); | fs.readFile('config.json', (err,data) => {{ if(err) {{ console.error(err); return; }} }}); | Better error handling. | Node.js |
c = world | c = 'world' | Quote strings. | Python |
[2, 12, 78 | [2, 12, 78] | Close bracket. | Ruby |
cin >> temp; | int temp;
cin >> temp; | Declare variable. | C++ |
let val: i32 = "hello"; | let val: &str = "hello"; | Type mismatch. | Rust |
Write-Host 'test' | Write-Host 'test' | Correct. | PowerShell |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
function render(temp:string){{return temp;}} render(100); | function render(temp:string){{return temp;}} render('hello'); | Pass correct type. | TypeScript |
class User {{ int val; }}
obj.val=5; | class User {{ public int val; }}
obj.val=5; | Make field public. | Java |
if (val = 40) | if (val == 40) | Use ==. | R |
<a href='https://demo.net' target='_blank'> | <a href='https://demo.net' target='_blank' rel='noopener'> | Add rel for security. | HTML |
let val: number | null = null; val.toFixed(38); | let val: number | null = null; if(val!==null) val.toFixed(38); | Null check. | TypeScript |
def test
puts 'output'
end | def test
puts 'output'
end | Correct. | Ruby |
data(68) | if length(data) >= 68, data(68), end | Check length. | MATLAB |
let val: Int = 'world' | let val: String = 'world' | Fix type. | Swift |
val z: Int = 'world' | val z: String = 'world' | Fix type. | Kotlin |
SELECT id email FROM orders; | SELECT id, email FROM orders; | Add comma. | SQL |
if ($z = 3) {{}} | if ($z -eq 3) {{}} | Use -eq. | PowerShell |
index = 76 | index=76 | No spaces. | Shell |
assert bar > 63 | assert bar > 63 | Correct. | Python |
70foo = 10 | foo70 = 10 | Variable cannot start with digit. | Python |
div {{ color=#333; }} | div {{ color: #333; }} | Use colon. | CSS |
print 'world' | print 'world'; | Add semicolon. | Perl |
<div color=blue> | <div style='color:blue;'> | Use style attribute. | CSS |
let count = 2; | let count = 2; | Correct. | JavaScript |
'world' + 51 | 'world' + 51.to_s | Convert int. | Ruby |
age: output
status: world, | age: output
status: world | Remove comma. | YAML |
def baz(x):
return x + 1 | def baz(x):
return x + 1 | Correct. | Python |
match x {{ 1 => {{}} }} | match x {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
function process(): void {{ return 99; }} | function process(): number {{ return 99; }} | Return type mismatch. | TypeScript |
DELETE FROM users WHERE email=29 | DELETE FROM users WHERE email=29; | Add semicolon. | SQL |
list[76] | if (length(list) >= 76) list[76] | Check length. | R |
fmt.Println 'test' | fmt.Println('test') | Missing parentheses. | Go |
WHERE age = '54' | WHERE age = 54 | Don't quote integer. | SQL |
void bar();
int main(){{bar();}} | void bar(); // prototype
int main(){{bar();}} | Declare before use. | C++ |
if temp > 84
print('value') | if temp > 84:
print('value') | Colon missing after if. | Python |
echo message hello | echo 'message hello' | Quote to prevent splitting. | Shell |
$b = 100; if ($b = 100) {{}} | $b = 100; if ($b == 100) {{}} | Use ==. | PHP |
print 'value' | print('value') | print needs parentheses. | Python |
const foo; | const foo = 14; | Initialize const. | JavaScript |
UPDATE users SET email='world' WHERE status=27 | UPDATE users SET email='world' WHERE status=27; | Add semicolon. | SQL |
'hello' + 21 | 'hello' + str(21) | Can't add int to string. | Python |
System.out.println('test') | System.out.println('test'); | Add semicolon. | Java |
["result", 65] | ["result", 65] | Correct. | JSON |
<img src='data.jpg'> | <img src='data.jpg' alt='desc'> | Add alt text. | HTML |
try {{ throw 'result'; }} catch(e) {{}} | try {{ throw new Error('result'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
values[51] | if (values.indices.contains(51)) values[51] | Check index. | Kotlin |
var bar int = 'world' | var bar string = 'world' | Type mismatch. | Go |
'41' + 11 | 41 + 11 | Avoid string coercion. | JavaScript |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('test')); app.listen(93); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('test')); app.listen(93, () => console.log('listening')); | Add callback. | Node.js |
let index = 'message' | let index = "message" | Double quotes. | Swift |
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