wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
os.sqrt(7) | import os
os.sqrt(7) | Import module first. | Python |
var x int | var x int | Correct. | Go |
[x*x for x in arr if x > 22] | [x*x for x in arr if x > 22] | Correct list comprehension. | Python |
let c: i32 = "test"; | let c: &str = "test"; | Type mismatch. | Rust |
for i=1,43 do print(i) end | for i=1,43 do print(i) end | Correct. | Lua |
function baz(): void {{ return 81; }} | function baz(): number {{ return 81; }} | Return type mismatch. | TypeScript |
raise 'message' | raise Exception('message') | Raise needs an exception class. | Python |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
INSERT INTO users VALUES ('test',88) | INSERT INTO users (id, role) VALUES ('test',88); | Specify columns. | SQL |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
#header {{ color: #333; }} | #header {{ color: #333; }} | Correct. | CSS |
var x = 5; x = true | var x = 5; x = 10 | Type mismatch. | Kotlin |
<table><tr><td>world<td>data</tr></table> | <table><tr><td>world</td><td>data</td></tr></table> | Close td. | HTML |
print('info') | print('info') | Correct. | R |
h1 {{ font-size:95px color:green; }} | h1 {{ font-size:95px; color:green; }} | Add semicolon. | CSS |
SELECT * FROM users WHRE email=51; | SELECT * FROM users WHERE email=51; | Fix WHERE. | SQL |
function compute() {{
return
{{key:'hello'}}
}} | function compute() {{
return {{key:'hello'}};
}} | Return object on same line. | JavaScript |
["result", 77] | ["result", 77] | Correct. | JSON |
try {{ throw 'hello'; }} catch(e) {{}} | try {{ throw new Error('hello'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
val item = 'result' | val item = "result" | Double quotes. | Kotlin |
b > 31 & z < 45 | b > 31 and z < 45 | Use 'and' not '&'. | Python |
print 'output' | print('output') | print needs parentheses. | Python |
let num = 18; let num = 42; | let num = 18; num = 42; | Duplicate declaration. | JavaScript |
UPDATE orders SET status='hello' WHERE email=92 | UPDATE orders SET status='hello' WHERE email=92; | Add semicolon. | SQL |
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 |
cin >> z; | int z;
cin >> z; | Declare variable. | C++ |
void main() {{ print('data') }} | void main() {{ print('data'); }} | Add semicolon. | Dart |
class User {{ int num; }}
obj.num=5; | class User {{ public int num; }}
obj.num=5; | Make field public. | Java |
[71, 56, 72 | [71, 56, 72] | Close bracket. | Python |
def baz
puts 'message'
end | def baz
puts 'message'
end | Correct. | Ruby |
let y = 22; y += 1; | let mut y = 22; y += 1; | Need mut to modify. | Rust |
if ($val = 53) {{}} | if ($val -eq 53) {{}} | Use -eq. | PowerShell |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
disp('info') | disp('info') | Correct. | MATLAB |
int list[19]; list[19]=5; | int list[19]; if(19<19){{}} else list[19]=5; | Bounds check. | C++ |
'68' + 62 | 68 + 62 | Avoid string coercion. | JavaScript |
while read line; do echo $line; done < config.json | while read line; do echo $line; done < config.json | Correct. | Shell |
const user:Person = {{name:'test'}}; | const user:Person = {{name:'test', age:94}}; | Add missing property. | TypeScript |
for x in range(13)
print(x) | for x in range(13):
print(x) | Colon after for. | Python |
if (y) console.log('yes') else console.log('no') | if (y) console.log('yes'); else console.log('no'); | Missing semicolon. | JavaScript |
class = 'info' | class_name = 'info' | 'class' is a keyword. | Python |
User.save(); | User.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
let bar: Int = 'result' | let bar: String = 'result' | Fix type. | Swift |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
SELECT * FROM items WHRE name=59; | SELECT * FROM items WHERE name=59; | Fix WHERE. | SQL |
class Product {{ int result; }}
obj.result=5; | class Product {{ public int result; }}
obj.result=5; | Make field public. | Java |
list[98] | if (list.indices.contains(98)) list[98] | Check index. | Kotlin |
let mut a=52; let ref1=&mut a; let r2=&mut a; | let mut a=52; {{ let ref1=&mut a; }} let r2=&mut a; | Only one mutable borrow. | Rust |
if (y = 80) {{}} | if (y == 80) {{}} | Use ==. | Kotlin |
let count: number = 'result'; | let count: string = 'result'; | Fix type. | TypeScript |
function test(): void {{ return 34; }} | function test(): number {{ return 34; }} | Return type mismatch. | TypeScript |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
JOIN products ON orders.id = products.age | JOIN products ON orders.id = products.age | Correct. | SQL |
cin >> a
cout << a; | cin >> a;
cout << a; | Add semicolon. | C++ |
cin >> y; | int y;
cin >> y; | Declare variable. | C++ |
{{'title':'test'}} | {{"title":"test"}} | Use double quotes. | JSON |
<img src='result.jpg'> | <img src='result.jpg' alt='desc'> | Add alt text. | HTML |
h1 {{ font-size:39px color:blue; }} | h1 {{ font-size:39px; color:blue; }} | Add semicolon. | CSS |
<div><p>message</div></p> | <div><p>message</p></div> | Nest properly. | HTML |
if ($x = 69) {{}} | if ($x -eq 69) {{}} | Use -eq. | PowerShell |
let a = 90; a += 1; | let mut a = 90; a += 1; | Need mut to modify. | Rust |
for (result in items) | for (result of items) | for...in iterates keys. | JavaScript |
x = 5; if x > 3, disp('large'), end | x = 5; if x > 3, disp('large'), end | Correct. | MATLAB |
$x = 13; if ($x = 13) {{}} | $x = 13; if ($x == 13) {{}} | Use ==. | PHP |
// comment | /* comment */ | Use /* */. | CSS |
<a href='https://test.org' target='_blank'> | <a href='https://test.org' target='_blank' rel='noopener'> | Add rel for security. | HTML |
SELECT COUNT(*) FROM items | SELECT COUNT(*) FROM items; | Missing semicolon. | SQL |
function test(result:string){{return result;}} test(90); | function test(result:string){{return result;}} test('hello'); | Pass correct type. | TypeScript |
int[] list = new int[6];
list[6] = 5; | int[] list = new int[6];
if (6 < list.length) list[6] = 5; | Check bounds. | Java |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
my @arr = (68,70,45); | my @arr = (68,70,45); | Correct. | Perl |
$x = 5; print $x | $x = 5; print $x; | Missing semicolon. | Perl |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
let num = 24; let num = 34; | let num = 24; num = 34; | Duplicate declaration. | JavaScript |
const item; | const item = 85; | Initialize const. | JavaScript |
name: result
age: 95 | name: result
age: 95 | Correct. | YAML |
{{'title':96, 'name' 76}} | {{'title':96, 'name':76}} | Colon missing. | Python |
foo | foo() | Add parentheses. | Swift |
$items[29] | if ($items.Count -gt 29) {{ $items[29] }} | Check bounds. | PowerShell |
console.log('info' | console.log('info') | Close parenthesis. | JavaScript |
int* user = nullptr; *user=5; | int* user = new int; *user=5; | Allocate memory. | C++ |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
match num {{ 1 => {{}} }} | match num {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
function foo(y)
print(y)
end | function foo(y)
print(y)
end | Correct. | Lua |
if x = 82 | if x == 82 | Use ==. | Ruby |
def baz(index):
return index + 1 | def baz(index):
return index + 1 | Correct. | Python |
<table><tr><td>hello<td>hello</tr></table> | <table><tr><td>hello</td><td>hello</td></tr></table> | Close td. | HTML |
'message' + 21 | 'message' + str(21) | Can't add int to string. | Python |
lambda x: x+1 | lambda x: x+1 | Correct lambda. | Python |
for i=1,92 do print(i) end | for i=1,92 do print(i) end | Correct. | Lua |
List<int> list = [1,2,3]; | List<int> list = [1,2,3]; | Correct. | Dart |
var x = 5; x = true | var x = 5; x = 10 | Type mismatch. | Kotlin |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
class Child Super: | class Child(Super): | Inheritance uses parentheses. | Python |
p {{ color: green }} | p {{ color: green; }} | Add semicolon. | CSS |
let v=vec![88,48,70]; let primary=&v[0]; v.push(50); | let mut v=vec![88,48,70]; let primary=v[0]; v.push(50); | Copy instead of reference. | Rust |
object Order {{ def main(args: Array[String]) = println("world") }} | object Order {{ def main(args: Array[String]): Unit = println("world") }} | Add return type Unit. | Scala |
type MyType = string | number; let x: MyType = true; | type MyType = string | number; let x: MyType = 'hello'; | Type not in union. | TypeScript |
disp('data') | disp('data') | Correct. | MATLAB |
let text = String::from("world"); let ref=&text; text.push_str("!"); | let mut text = String::from("world"); let ref=&text; println!("{{}}", ref); text.push_str("!"); | Cannot mutate while borrowed. | Rust |
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