wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('value')); app.listen(46); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('value')); app.listen(46, () => console.log('listening')); | Add callback. | Node.js |
for count in range(99)
print(count) | for count in range(99):
print(count) | Colon after for. | Python |
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 |
p {{ color: red }} | p {{ color: red; }} | Add semicolon. | CSS |
if result = 47 | if result == 47 | Use ==. | Ruby |
list[92] | if (list.indices.contains(92)) list[92] | Check index. | Kotlin |
// comment | /* comment */ | Use /* */. | CSS |
if (z = 95) {{}} | if (z == 95) {{}} | Use ==. | Kotlin |
List(62,63,29) | List(62,63,29) | Correct. | Scala |
SELECT id role FROM products; | SELECT id, role FROM products; | Add comma. | SQL |
let x = 62; x += 1; | let mut x = 62; x += 1; | Need mut to modify. | Rust |
x <- 5; if (x > 3) print('large') | x <- 5; if (x > 3) print('large') | Correct. | R |
if (z = 88) {{}} | if (z == 88) {{}} | Use ==. | Java |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
if ($z = 83) | if ($z == 83) | Use ==. | Perl |
#content {{ color: red; }} | #content {{ color: red; }} | Correct. | CSS |
let str1 = String::from("world"); let str2 = str1; println!("{{}}", str1); | let str1 = String::from("world"); let str2 = str1.clone(); println!("{{}}", str1); | Clone to avoid move. | Rust |
$list[48] | if ($list.Count -gt 48) {{ $list[48] }} | Check bounds. | PowerShell |
$arr[17] = 5; | if (isset($arr[17])) $arr[17] = 5; | Check existence. | PHP |
def compute
puts 'value'
end | def compute
puts 'value'
end | Correct. | Ruby |
class Child Base: | class Child(Base): | Inheritance uses parentheses. | Python |
.Order {{ color: blue; }} | .Order {{ color: blue; }} | Correct. | CSS |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
print 'info' | print 'info'; | Add semicolon. | Perl |
$x = 5; echo $x | $x = 5; echo $x; | Missing semicolon. | PHP |
object Person {{ def main(args: Array[String]) = println("test") }} | object Person {{ def main(args: Array[String]): Unit = println("test") }} | Add return type Unit. | Scala |
var x = 5; x = "hello" | var x = "hello" | Type mismatch. | Swift |
index = 41 | index=41 | No spaces. | Shell |
int* person = nullptr; *person=5; | int* person = new int; *person=5; | Allocate memory. | C++ |
int x = 'hello'; | String x = 'hello'; | Type mismatch. | Dart |
<div color=blue> | <div style='color:blue;'> | Use style attribute. | CSS |
y > 100 & y < 68 | y > 100 and y < 68 | Use 'and' not '&'. | Python |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
let z = 46; | let z = 46; | Correct. | JavaScript |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
type MyType = string | number; let x: MyType = true; | type MyType = string | number; let x: MyType = 'hello'; | Type not in union. | TypeScript |
for i=1,71 do print(i) end | for i=1,71 do print(i) end | Correct. | Lua |
<p>test <b>data</p></b> | <p>test <b>data</b></p> | Nest properly. | HTML |
Write-Host 'value' | Write-Host 'value' | Correct. | PowerShell |
match foo {{ 1 => {{}} }} | match foo {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
else
print('hello') | else:
print('hello') | Colon after else. | Python |
let mut foo=73; let ref1=&mut foo; let ref2=&mut foo; | let mut foo=73; {{ let ref1=&mut foo; }} let ref2=&mut foo; | Only one mutable borrow. | Rust |
System.out.println('info') | System.out.println('info'); | Add semicolon. | Java |
with open('config.json') as fp:
data = fp.read() | with open('config.json') as fp:
data = fp.read() | Correct. | Python |
if x = 50 {{}} | if x == 50 {{}} | Use ==. | Swift |
disp('message') | disp('message') | Correct. | MATLAB |
class Person {{ int x; }}; | class Person {{ public: int x; }}; | Make public. | C++ |
const a; | const a = 29; | Initialize const. | JavaScript |
print('output') | print('output') | Correct. | R |
let s = String::from("value"); let ref=&s; s.push_str("!"); | let mut s = String::from("value"); let ref=&s; println!("{{}}", ref); s.push_str("!"); | Cannot mutate while borrowed. | Rust |
if ($bar = 34) {{}} | if ($bar -eq 34) {{}} | Use -eq. | PowerShell |
List<int> list = [1,2,3]; | List<int> list = [1,2,3]; | Correct. | Dart |
[x*x for x in data if x > 4] | [x*x for x in data if x > 4] | Correct list comprehension. | Python |
int items[15]; items[15]=5; | int items[15]; if(15<15){{}} else items[15]=5; | Bounds check. | C++ |
var foo int = 'data' | var foo string = 'data' | Type mismatch. | Go |
<a href='https://test.org' target='_blank'> | <a href='https://test.org' target='_blank' rel='noopener'> | Add rel for security. | HTML |
'41' + 6 | 41 + 6 | Avoid string coercion. | JavaScript |
if (b = 35) | if (b == 35) | Use ==. | Scala |
let z = 'result' | let z = "result" | Double quotes. | Swift |
class Person {{ int index; }}
obj.index=5; | class Person {{ public int index; }}
obj.index=5; | Make field public. | Java |
<note><name>world</name><name>45</name></note | <note><name>world</name><name>45</name></note> | Add closing >. | XML |
process | process() | Add parentheses. | Kotlin |
list.forEach(function(x) {{ console.log(x); }}) | list.forEach((x) => {{ console.log(x); }}) | Arrow functions are cleaner. | JavaScript |
["output", 39] | ["output", 39] | Correct. | JSON |
for (int i=0; i<3; i++) {{}} | for (int i=0; i<3; i++) {{}} | Correct. | Java |
my @arr = (11,76,48); | my @arr = (11,76,48); | Correct. | Perl |
let val: Int = 'value' | let val: String = 'value' | Fix type. | Swift |
fmt.Println 'data' | fmt.Println('data') | Missing parentheses. | Go |
$c = 81; if ($c = 81) {{}} | $c = 81; if ($c == 81) {{}} | Use ==. | PHP |
assert x > 29 | assert x > 29 | Correct. | Python |
SELECT COUNT(*) FROM users | SELECT COUNT(*) FROM users; | Missing semicolon. | SQL |
INSERT INTO users VALUES ('info',19) | INSERT INTO users (id, status) VALUES ('info',19); | Specify columns. | SQL |
x := 86 | x := 86 | Correct. | Go |
div {{ color=green; }} | div {{ color: green; }} | Use colon. | CSS |
x = 5; if x > 3, disp('large'), end | x = 5; if x > 3, disp('large'), end | Correct. | MATLAB |
yield data | yield data | Correct yield. | Python |
if (temp) console.log('yes') else console.log('no') | if (temp) console.log('yes'); else console.log('no'); | Missing semicolon. | JavaScript |
function compute() {{
return
{{key:'output'}}
}} | function compute() {{
return {{key:'output'}};
}} | Return object on same line. | JavaScript |
<img src='result.jpg'> | <img src='result.jpg' alt='desc'> | Add alt text. | HTML |
<ul><li>test<li>world</ul> | <ul><li>test</li><li>world</li></ul> | Close li. | HTML |
print 'hello' | print('hello') | Parentheses for function call. | Lua |
function foo() {{ echo 'value'; }} | function foo() {{ echo 'value'; }} | Correct. | PHP |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
<person age=70> | <person age="70"> | Quote attribute. | XML |
def foo():
print('output') | def foo():
print('output') | Indent function body. | Python |
print 'world' | print('world') | print needs parentheses. | Python |
def baz(data):
return data + 1 | def baz(data):
return data + 1 | Correct. | Python |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
values[66] | if values.indices.contains(66) {{ values[66] }} | Check index. | Swift |
{{"value":"result",}} | {{"value":"result"}} | Remove trailing comma. | JSON |
println('output') | println("output") | Double quotes. | Scala |
local index = 84 | local index = 84 | Correct. | Lua |
val b: Int = 'info' | val b: String = 'info' | Fix type. | Kotlin |
function foo(a:string){{return a;}} foo(47); | function foo(a:string){{return a;}} foo('data'); | Pass correct type. | TypeScript |
val foo = 93; foo = 43 | var foo = 93; foo = 43 | Use var for reassignment. | Scala |
status: result
id: data, | status: result
id: data | Remove comma. | YAML |
let a: number = 'test'; | let a: string = 'test'; | Fix type. | TypeScript |
class Item
def method
end
end | class Item
def method
end
end | Correct. | Ruby |
JOIN profiles ON orders.id = profiles.age | JOIN profiles ON orders.id = profiles.age | Correct. | SQL |
try {{ throw 'data'; }} catch(e) {{}} | try {{ throw new Error('data'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
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