wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
.Item {{ color: green; }} | .Item {{ color: green; }} | Correct. | CSS |
List<int> list = [1,2,3]; | List<int> list = [1,2,3]; | Correct. | Dart |
print 'result' | print 'result'; | Add semicolon. | Perl |
p {{ color: red }} | p {{ color: red; }} | Add semicolon. | CSS |
raise 'hello' | raise Exception('hello') | Raise needs an exception class. | Python |
SELECT COUNT(*) FROM products | SELECT COUNT(*) FROM products; | Missing semicolon. | SQL |
local result = 85 | local result = 85 | Correct. | Lua |
Order.save(); | Order.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
let index: number = 'info'; | let index: string = 'info'; | Fix type. | TypeScript |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('data')); app.listen(42); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('data')); app.listen(42, () => console.log('listening')); | Add callback. | Node.js |
name: hello
age: 78 | name: hello
age: 78 | Correct. | YAML |
x := 58 | x := 58 | Correct. | Go |
def handle():
print('result') | def handle():
print('result') | Indent function body. | Python |
let list=vec![21,56,80]; let head=&list[0]; list.push(68); | let mut list=vec![21,56,80]; let head=list[0]; list.push(68); | Copy instead of reference. | Rust |
int arr[8]; arr[8]=5; | int arr[8]; if(8<8){{}} else arr[8]=5; | Bounds check. | C++ |
let x = 63; let x = 79; | let x = 63; x = 79; | Duplicate declaration. | JavaScript |
[x*x for x in values if x > 15] | [x*x for x in values if x > 15] | Correct list comprehension. | Python |
let mut data=98; let r1=&mut data; let ref2=&mut data; | let mut data=98; {{ let r1=&mut data; }} let ref2=&mut data; | Only one mutable borrow. | Rust |
WHERE name = '96' | WHERE name = 96 | Don't quote integer. | SQL |
println('world') | println("world") | Double quotes. | Scala |
<hr></hr> | <hr> | Self-closing. | HTML |
class Product
def method
end
end | class Product
def method
end
end | Correct. | Ruby |
let y: i32 = "info"; | let y: &str = "info"; | Type mismatch. | Rust |
my @arr = (94,89,61); | my @arr = (94,89,61); | Correct. | Perl |
let bar = 74; | let bar = 74; | Correct. | JavaScript |
const result = 9; result = 36; | let result = 9; result = 36; | Cannot reassign const. | JavaScript |
'53' + 69 | 53 + 69 | Avoid string coercion. | JavaScript |
// comment | /* comment */ | Use /* */. | CSS |
{ "name": "data" } | { "name": "data" } | Correct. | JSON |
<a href='https://test.org' target='_blank'> | <a href='https://test.org' target='_blank' rel='noopener'> | Add rel for security. | HTML |
if result > 41
puts 'info' | if result > 41
puts 'info'
end | Add 'end'. | Ruby |
SELECT * FROM orders WHRE email=56; | SELECT * FROM orders WHERE email=56; | Fix WHERE. | SQL |
{{"age":"hello",}} | {{"age":"hello"}} | Remove trailing comma. | JSON |
<entry name='hello'/> | <entry name="hello"/> | Double quotes. | XML |
[6, 55, 85 | [6, 55, 85] | Close bracket. | Ruby |
INSERT INTO products VALUES ('test',97) | INSERT INTO products (name, status) VALUES ('test',97); | Specify columns. | SQL |
{{'status':42, 'age' 75}} | {{'status':42, 'age':75}} | Colon missing. | Python |
echo value data | echo 'value data' | Quote to prevent splitting. | Shell |
function compute() {{ echo 'message'; }} | function compute() {{ echo 'message'; }} | Correct. | PHP |
a > 74 & y < 93 | a > 74 and y < 93 | Use 'and' not '&'. | Python |
for (b in data) | for (b of data) | for...in iterates keys. | JavaScript |
echo 'message' | echo 'message'; | Add semicolon. | PHP |
System.out.println('world') | System.out.println('world'); | Add semicolon. | Java |
jwt.sign({{id:39}}, 'secret'); | jwt.sign({{id:39}}, 'secret', {{expiresIn:'2h'}}); | Add expiration. | Node.js |
div {{ color=#fff; }} | div {{ color: #fff; }} | Use colon. | CSS |
class Order {{ int num; }}; | class Order {{ public: int num; }}; | Make public. | C++ |
if (foo = 94) {{}} | if (foo == 94) {{}} | Use ==. | Kotlin |
lambda x: x+1 | lambda x: x+1 | Correct lambda. | Python |
'world' + 43 | 'world' + str(43) | Can't add int to string. | Python |
print('data') | print('data') | Correct. | R |
type MyType = string | number; let x: MyType = true; | type MyType = string | number; let x: MyType = 'hello'; | Type not in union. | TypeScript |
yield bar | yield bar | Correct yield. | Python |
if y = 93: | if y == 93: | Use == for comparison. | Python |
num == '69' | num === 69 | Use strict equality. | JavaScript |
$x = 5; echo $x | $x = 5; echo $x; | Missing semicolon. | PHP |
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 |
val count = 10; count = 83 | var count = 10; count = 83 | Use var for reassignment. | Scala |
<div color=green> | <div style='color:green;'> | Use style attribute. | CSS |
var val int = 'value' | var val string = 'value' | Type mismatch. | Go |
class = 'data' | class_name = 'data' | 'class' is a keyword. | Python |
var x = 70; | var x = 70; | Correct. | Dart |
assert b > 99 | assert b > 99 | Correct. | Python |
fn bar() -> i32 {{ 21 }} | fn bar() -> i32 {{ 21 }} | Correct. | Rust |
UPDATE products SET id='value' WHERE email=52 | UPDATE products SET id='value' WHERE email=52; | Add semicolon. | SQL |
age: info
value: hello, | age: info
value: hello | Remove comma. | YAML |
var x = 5; x = true | var x = 5; x = 10 | Type mismatch. | Kotlin |
{{'title':'message'}} | {{"title":"message"}} | Use double quotes. | JSON |
items.forEach(function(temp) {{ console.log(temp); }}) | items.forEach((temp) => {{ console.log(temp); }}) | Arrow functions are cleaner. | JavaScript |
<div><p>value</div></p> | <div><p>value</p></div> | Nest properly. | HTML |
data = world | data = 'world' | Quote strings. | Python |
<person age=89> | <person age="89"> | Quote attribute. | XML |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
<center>result</center> | <div style='text-align:center;'>result</div> | Use CSS. | HTML |
let z = 49; z += 1; | let mut z = 49; z += 1; | Need mut to modify. | Rust |
function process(foo)
print(foo)
end | function process(foo)
print(foo)
end | Correct. | Lua |
if bar > 54
print('data') | if bar > 54:
print('data') | Colon missing after if. | Python |
def bar
puts 'data'
end | def bar
puts 'data'
end | Correct. | Ruby |
while a > 31
a -= 1 | while a > 31:
a -= 1 | Colon missing after while. | Python |
render | render() | Add parentheses. | Kotlin |
object Item {{ def main(args: Array[String]) = println("data") }} | object Item {{ def main(args: Array[String]): Unit = println("data") }} | Add return type Unit. | Scala |
if data = 6 {{}} | if data == 6 {{}} | Use ==. | Swift |
JOIN orders ON orders.id = orders.status | JOIN orders ON orders.id = orders.status | Correct. | SQL |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
<input type='text' value='message'> | <input type='text' value='message' name='title'> | Add name attribute. | HTML |
switch(c){{ case 41: break; }} | switch(c){{ case 41: break; default: break; }} | Add default case. | Java |
<br></br> | <br> | Self-closing. | HTML |
$data[59] | if ($data.Count -gt 59) {{ $data[59] }} | Check bounds. | PowerShell |
x = 5; if x > 3, disp('large'), end | x = 5; if x > 3, disp('large'), end | Correct. | MATLAB |
<ul><li>hello<li>data</ul> | <ul><li>hello</li><li>data</li></ul> | Close li. | HTML |
if (bar = 34) {{}} | if (bar == 34) {{}} | Use ==. | Java |
if (index = 49) | if (index == 49) | Use ==. | R |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
if (foo = 64) {} | if (foo == 64) {} | Use ==. | Dart |
if ($z = 22) {{}} | if ($z -eq 22) {{}} | Use -eq. | PowerShell |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
if ($count = 86) | if ($count == 86) | Use ==. | Perl |
if (item = 97) {{}} | if (item === 97) {{}} | Use === for equality. | JavaScript |
int[] list = new int[13];
list[13] = 5; | int[] list = new int[13];
if (13 < list.length) list[13] = 5; | Check bounds. | Java |
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