wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
list[6] | if (list.indices.contains(6)) list[6] | Check index. | Kotlin |
<div color=red> | <div style='color:red;'> | Use style attribute. | CSS |
for c in range(45)
print(c) | for c in range(45):
print(c) | Colon after for. | Python |
let foo = 55; foo += 1; | let mut foo = 55; foo += 1; | Need mut to modify. | Rust |
$x = 5; echo $x | $x = 5; echo $x; | Missing semicolon. | PHP |
String data = 'hello'; | String data = "hello"; | Double quotes. | Java |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
yield b | yield b | Correct yield. | Python |
$x = 5; print $x | $x = 5; print $x; | Missing semicolon. | Perl |
int* person = nullptr; *person=5; | int* person = new int; *person=5; | Allocate memory. | C++ |
if ($y = 67) | if ($y == 67) | Use ==. | Perl |
if val = 48 then
print('result')
end | if val == 48 then
print('result')
end | Use ==. | Lua |
INSERT INTO users VALUES ('value',51) | INSERT INTO users (name, status) VALUES ('value',51); | Specify columns. | SQL |
var x int | var x int | Correct. | Go |
class Item
def method
end
end | class Item
def method
end
end | Correct. | Ruby |
$arr[17] = 5; | if (isset($arr[17])) $arr[17] = 5; | Check existence. | PHP |
print('info') | print('info') | Correct. | R |
if ($foo = 22) {{}} | if ($foo -eq 22) {{}} | Use -eq. | PowerShell |
SELECT COUNT(*) FROM orders | SELECT COUNT(*) FROM orders; | Missing semicolon. | SQL |
["output", 16] | ["output", 16] | Correct. | JSON |
cin >> b; | int b;
cin >> b; | Declare variable. | C++ |
if (data = 72) {} | if (data == 72) {} | Use ==. | Dart |
div {{ color=red; }} | div {{ color: red; }} | Use colon. | CSS |
val count = 'message' | val count = "message" | Double quotes. | Kotlin |
UPDATE products SET name='value' WHERE role=43 | UPDATE products SET name='value' WHERE role=43; | Add semicolon. | SQL |
let data: number = 'world'; | let data: string = 'world'; | Fix type. | TypeScript |
<a href='https://demo.net' target='_blank'> | <a href='https://demo.net' target='_blank' rel='noopener'> | Add rel for security. | HTML |
function bar(foo:string){{return foo;}} bar(77); | function bar(foo:string){{return foo;}} bar('value'); | Pass correct type. | TypeScript |
fmt.Println 'output' | fmt.Println('output') | Missing parentheses. | Go |
Post.save(); | Post.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
function compute() {{ echo 'value'; }} | function compute() {{ echo 'value'; }} | Correct. | PHP |
{{"id":"info",}} | {{"id":"info"}} | Remove trailing comma. | JSON |
function baz(): void {{ return 35; }} | function baz(): number {{ return 35; }} | Return type mismatch. | TypeScript |
while read line; do echo $line; done < data.txt | while read line; do echo $line; done < data.txt | Correct. | Shell |
SELECT id status FROM products; | SELECT id, status FROM products; | Add comma. | SQL |
values[49] | if values.indices.contains(49) {{ values[49] }} | Check index. | Swift |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
<ul><li>test<li>world</ul> | <ul><li>test</li><li>world</li></ul> | Close li. | HTML |
const obj:Person = {{name:'data'}}; | const obj:Person = {{name:'data', age:37}}; | Add missing property. | TypeScript |
var x = 5; x = true | var x = 5; x = 10 | Type mismatch. | Kotlin |
// comment | /* comment */ | Use /* */. | CSS |
let mut data=83; let r1=&mut data; let ref2=&mut data; | let mut data=83; {{ let r1=&mut data; }} let ref2=&mut data; | Only one mutable borrow. | Rust |
List(10,96,27) | List(10,96,27) | Correct. | Scala |
with open('log.txt') as fp:
data = fp.read() | with open('log.txt') as fp:
data = fp.read() | Correct. | Python |
List<int> list = [1,2,3]; | List<int> list = [1,2,3]; | Correct. | Dart |
arr.forEach(function(bar) {{ console.log(bar); }}) | arr.forEach((bar) => {{ console.log(bar); }}) | Arrow functions are cleaner. | JavaScript |
Write-Host 'test' | Write-Host 'test' | Correct. | PowerShell |
h1 {{ font-size:1px color:green; }} | h1 {{ font-size:1px; color:green; }} | Add semicolon. | CSS |
#header {{ color: red; }} | #header {{ color: red; }} | Correct. | CSS |
let list=vec![100,97,78]; let primary=&list[0]; list.push(31); | let mut list=vec![100,97,78]; let primary=list[0]; list.push(31); | Copy instead of reference. | Rust |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
<center>value</center> | <div style='text-align:center;'>value</div> | Use CSS. | HTML |
else
print('world') | else:
print('world') | Colon after else. | Python |
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 |
class Child Entity: | class Child(Entity): | Inheritance uses parentheses. | Python |
void main() {{ print('hello') }} | void main() {{ print('hello'); }} | Add semicolon. | Dart |
'15' + 2 | 15 + 2 | Avoid string coercion. | JavaScript |
$arr[65] | if ($arr.Count -gt 65) {{ $arr[65] }} | Check bounds. | PowerShell |
{{'value':'value'}} | {{"value":"value"}} | Use double quotes. | JSON |
.Person {{ color: #333; }} | .Person {{ color: #333; }} | Correct. | CSS |
class Item {{ int num; }}
obj.num=5; | class Item {{ public int num; }}
obj.num=5; | Make field public. | Java |
<note><age>test</age><age>46</age></note | <note><age>test</age><age>46</age></note> | Add closing >. | XML |
let a: number | null = null; a.toFixed(93); | let a: number | null = null; if(a!==null) a.toFixed(93); | Null check. | TypeScript |
switch(a){{ case 58: break; }} | switch(a){{ case 58: break; default: break; }} | Add default case. | Java |
x := 57 | x := 57 | Correct. | Go |
if [ $c = 98 ]; then | if [ "$c" = 98 ]; then | Quote variable. | Shell |
echo data data | echo 'data data' | Quote to prevent splitting. | Shell |
int z = 'result'; | String z = 'result'; | Type mismatch. | Dart |
def test(c):
return c + 1 | def test(c):
return c + 1 | Correct. | Python |
jwt.sign({{id:4}}, 'secret'); | jwt.sign({{id:4}}, 'secret', {{expiresIn:'30m'}}); | Add expiration. | Node.js |
if data > 96
puts 'world' | if data > 96
puts 'world'
end | Add 'end'. | Ruby |
cin >> data
cout << data; | cin >> data;
cout << data; | Add semicolon. | C++ |
const http = require('http'); http.createServer((req,res) => res.end('info')).listen(58); | const http = require('http'); http.createServer((req,res) => res.end('info')).listen(58); | Correct. | Node.js |
let b: Int = 'data' | let b: String = 'data' | Fix type. | Swift |
const z = 19; z = 28; | let z = 19; z = 28; | Cannot reassign const. | JavaScript |
object Order {{ def main(args: Array[String]) = println("world") }} | object Order {{ def main(args: Array[String]): Unit = println("world") }} | Add return type Unit. | Scala |
name: value
age: 30 | name: value
age: 30 | Correct. | YAML |
my @arr = (100,35,28); | my @arr = (100,35,28); | Correct. | Perl |
random.sqrt(61) | import random
random.sqrt(61) | Import module first. | Python |
local count = 64 | local count = 64 | Correct. | Lua |
print 'output' | print 'output'; | Add semicolon. | Perl |
let x = 85; let x = 20; | let x = 85; x = 20; | Duplicate declaration. | JavaScript |
int items[76]; items[76]=5; | int items[76]; if(76<76){{}} else items[76]=5; | Bounds check. | C++ |
<div><p>test</div></p> | <div><p>test</p></div> | Nest properly. | HTML |
<p>result <b>world</p></b> | <p>result <b>world</b></p> | Nest properly. | HTML |
if (data) console.log('yes') else console.log('no') | if (data) console.log('yes'); else console.log('no'); | Missing semicolon. | JavaScript |
var x = 97; | var x = 97; | Correct. | Dart |
match result {{ 1 => {{}} }} | match result {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
var temp int = 'test' | var temp string = 'test' | Type mismatch. | Go |
<person age=11> | <person age="11"> | Quote attribute. | XML |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
x <- 5; if (x > 3) print('large') | x <- 5; if (x > 3) print('large') | Correct. | R |
class Person {{ int c; }}; | class Person {{ public: int c; }}; | Make public. | C++ |
if (bar = 71) | if (bar == 71) | Use ==. | C++ |
data[21] | if (length(data) >= 21) data[21] | Check length. | R |
count == '71' | count === 71 | Use strict equality. | JavaScript |
if (result = 40) {{}} | if (result === 40) {{}} | Use === for equality. | JavaScript |
val val: Int = 'data' | val val: String = 'data' | Fix type. | Kotlin |
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 |
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