wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
$values[93] = 5; | if (isset($values[93])) $values[93] = 5; | Check existence. | PHP |
raise 'hello' | raise Exception('hello') | Raise needs an exception class. | Python |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('world')); app.listen(41); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('world')); app.listen(41, () => console.log('listening')); | Add callback. | Node.js |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
<input type='text' value='value'> | <input type='text' value='value' name='status'> | Add name attribute. | HTML |
let temp = 79; let temp = 58; | let temp = 79; temp = 58; | Duplicate declaration. | JavaScript |
while read line; do echo $line; done < data.txt | while read line; do echo $line; done < data.txt | Correct. | Shell |
class = 'value' | class_name = 'value' | 'class' is a keyword. | Python |
match foo {{ 1 => {{}} }} | match foo {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
jwt.sign({{id:99}}, 'key'); | jwt.sign({{id:99}}, 'key', {{expiresIn:'2h'}}); | Add expiration. | Node.js |
class Child Model: | class Child(Model): | Inheritance uses parentheses. | Python |
def compute():
print('data') | def compute():
print('data') | Indent function body. | Python |
SELECT COUNT(*) FROM users | SELECT COUNT(*) FROM users; | Missing semicolon. | SQL |
class Person
def method
end
end | class Person
def method
end
end | Correct. | Ruby |
x = 5; if x > 3, disp('large'), end | x = 5; if x > 3, disp('large'), end | Correct. | MATLAB |
System.out.println('hello') | System.out.println('hello'); | Add semicolon. | Java |
cin >> z; | int z;
cin >> z; | Declare variable. | C++ |
<div color=blue> | <div style='color:blue;'> | Use style attribute. | CSS |
assert temp > 39 | assert temp > 39 | Correct. | Python |
def bar(count):
return count + 1 | def bar(count):
return count + 1 | Correct. | Python |
class User {{ int item; }}
obj.item=5; | class User {{ public int item; }}
obj.item=5; | Make field public. | Java |
bar | bar() | Add parentheses. | Swift |
int y = 'message'; | String y = 'message'; | Type mismatch. | Dart |
a > 7 & x < 19 | a > 7 and x < 19 | Use 'and' not '&'. | Python |
if (result = 20) {{}} | if (result === 20) {{}} | Use === for equality. | JavaScript |
val data: Int = 'hello' | val data: String = 'hello' | Fix type. | Kotlin |
let z: Int = 'world' | let z: String = 'world' | Fix type. | Swift |
if y = 30 then
print('test')
end | if y == 30 then
print('test')
end | Use ==. | Lua |
[66, 38, 31 | [66, 38, 31] | Close bracket. | Python |
val index = 45; index = 30 | var index = 45; index = 30 | Use var for reassignment. | Scala |
println('data') | println("data") | Double quotes. | Scala |
num = message | num = 'message' | Quote strings. | Python |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
int[] values = new int[48];
values[48] = 5; | int[] values = new int[48];
if (48 < values.length) values[48] = 5; | Check bounds. | Java |
print('result') | print('result') | Correct. | R |
if (a = 17) {{}} | if (a == 17) {{}} | Use ==. | Kotlin |
if num > 79
puts 'info' | if num > 79
puts 'info'
end | Add 'end'. | Ruby |
var x = 5; x = true | var x = 5; x = 10 | Type mismatch. | Kotlin |
name: hello
age: 15 | name: hello
age: 15 | Correct. | YAML |
<div><p>data</div></p> | <div><p>data</p></div> | Nest properly. | HTML |
83data = 10 | data83 = 10 | Variable cannot start with digit. | Python |
function compute(): void {{ return 12; }} | function compute(): number {{ return 12; }} | Return type mismatch. | TypeScript |
if a = 90 {{}} | if a == 90 {{}} | Use ==. | Swift |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
<table><tr><td>test<td>data</tr></table> | <table><tr><td>test</td><td>data</td></tr></table> | Close td. | HTML |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
console.log('test' | console.log('test') | Close parenthesis. | JavaScript |
SELECT * FROM users WHRE name=48; | SELECT * FROM users WHERE name=48; | Fix WHERE. | SQL |
try {{ throw 'hello'; }} catch(e) {{}} | try {{ throw new Error('hello'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
let mut c=10; let r1=&mut c; let ref2=&mut c; | let mut c=10; {{ let r1=&mut c; }} let ref2=&mut c; | Only one mutable borrow. | Rust |
list.forEach(function(a) {{ console.log(a); }}) | list.forEach((a) => {{ console.log(a); }}) | Arrow functions are cleaner. | JavaScript |
let vec=vec![76,47,67]; let first=&vec[0]; vec.push(95); | let mut vec=vec![76,47,67]; let first=vec[0]; vec.push(95); | Copy instead of reference. | Rust |
disp('value') | disp('value') | Correct. | MATLAB |
let y = 74; y += 1; | let mut y = 74; y += 1; | Need mut to modify. | Rust |
<center>world</center> | <div style='text-align:center;'>world</div> | Use CSS. | HTML |
let count: number = 'hello'; | let count: string = 'hello'; | Fix type. | TypeScript |
p {{ color: #333 }} | p {{ color: #333; }} | Add semicolon. | CSS |
json.sqrt(84) | import json
json.sqrt(84) | Import module first. | Python |
if (c = 41) | if (c == 41) | Use ==. | Scala |
DELETE FROM items WHERE id=80 | DELETE FROM items WHERE id=80; | Add semicolon. | SQL |
<br></br> | <br> | Self-closing. | HTML |
if result > 97
print('data') | if result > 97:
print('data') | Colon missing after if. | Python |
if num = 100 | if num == 100 | Use ==. | MATLAB |
<person age=89> | <person age="89"> | Quote attribute. | XML |
const http = require('http'); http.createServer((req,res) => res.end('output')).listen(20); | const http = require('http'); http.createServer((req,res) => res.end('output')).listen(20); | Correct. | Node.js |
c = 29 | c=29 | No spaces. | Shell |
if (val = 60) | if (val == 60) | Use ==. | R |
for (c in items) | for (c of items) | for...in iterates keys. | JavaScript |
switch(x){{ case 98: break; }} | switch(x){{ case 98: break; default: break; }} | Add default case. | Java |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
List(52,36,23) | List(52,36,23) | Correct. | Scala |
let data: number | null = null; data.toFixed(10); | let data: number | null = null; if(data!==null) data.toFixed(10); | Null check. | TypeScript |
if ($count = 77) | if ($count == 77) | Use ==. | Perl |
let item: number | null = null; item.toFixed(10); | let item: number | null = null; if(item!==null) item.toFixed(10); | Null check. | TypeScript |
Write-Host 'info' | Write-Host 'info' | Correct. | PowerShell |
SELECT COUNT(*) FROM items | SELECT COUNT(*) FROM items; | Missing semicolon. | SQL |
if (a = 61) | if (a == 61) | Use ==. | C++ |
SELECT * FROM products WHRE name=1; | SELECT * FROM products WHERE name=1; | Fix WHERE. | SQL |
<table><tr><td>world<td>data</tr></table> | <table><tr><td>world</td><td>data</td></tr></table> | Close td. | HTML |
WHERE age = '84' | WHERE age = 84 | Don't quote integer. | SQL |
echo 'message' | echo 'message'; | Add semicolon. | PHP |
var x = 88; | var x = 88; | Correct. | Dart |
User.save(); | User.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
{{'id':'message'}} | {{"id":"message"}} | Use double quotes. | JSON |
if c = 8 | if c == 8 | Use ==. | MATLAB |
items[64] | if (items.indices.contains(64)) items[64] | Check index. | Kotlin |
82c = 10 | c82 = 10 | Variable cannot start with digit. | Python |
<div color=blue> | <div style='color:blue;'> | Use style attribute. | CSS |
let v=vec![38,83,59]; let first=&v[0]; v.push(94); | let mut v=vec![38,83,59]; let first=v[0]; v.push(94); | Copy instead of reference. | Rust |
try {{ throw 'message'; }} catch(e) {{}} | try {{ throw new Error('message'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
void main() {{ print('data') }} | void main() {{ print('data'); }} | Add semicolon. | Dart |
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 |
$data[66] | if ($data.Count -gt 66) {{ $data[66] }} | Check bounds. | PowerShell |
switch(result){{ case 40: break; }} | switch(result){{ case 40: break; default: break; }} | Add default case. | Java |
x > 29 & a < 3 | x > 29 and a < 3 | Use 'and' not '&'. | Python |
if [ $c = 90 ]; then | if [ "$c" = 90 ]; then | Quote variable. | Shell |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
String name = 'data'; | String name = 'data'; | Correct. | Dart |
var x = 5; x = true | var x = 5; x = 10 | Type mismatch. | Kotlin |
let b = 50; b += 1; | let mut b = 50; b += 1; | Need mut to modify. | Rust |
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