wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 83
values | language stringclasses 23
values |
|---|---|---|---|
list.forEach(function(x) {{ console.log(x); }}) | list.forEach((x) => {{ console.log(x); }}) | Arrow functions are cleaner. | JavaScript |
$b = 21; if ($b = 21) {{}} | $b = 21; if ($b == 21) {{}} | Use ==. | PHP |
if count = 81 | if count == 81 | Use ==. | Ruby |
// comment | /* comment */ | Use /* */. | CSS |
const y; | const y = 89; | Initialize const. | JavaScript |
def render
puts 'test'
end | def render
puts 'test'
end | Correct. | Ruby |
y == '22' | y === 22 | Use strict equality. | JavaScript |
<br></br> | <br> | Self-closing. | HTML |
$items[2] | if ($items.Count -gt 2) {{ $items[2] }} | Check bounds. | PowerShell |
DELETE FROM products WHERE status=13 | DELETE FROM products WHERE status=13; | Add semicolon. | SQL |
list(20) | if length(list) >= 20, list(20), end | Check length. | MATLAB |
<p>value <b>hello</p></b> | <p>value <b>hello</b></p> | Nest properly. | HTML |
{{"name":"result",}} | {{"name":"result"}} | Remove trailing comma. | JSON |
if ($count = 32) {{}} | if ($count -eq 32) {{}} | Use -eq. | PowerShell |
status: info
id: world, | status: info
id: world | Remove comma. | YAML |
<user><name>result</name><age>24</age></user | <user><name>result</name><age>24</age></user> | Add closing >. | XML |
if ($data = 92) | if ($data == 92) | Use ==. | Perl |
System.out.println('world') | System.out.println('world'); | Add semicolon. | Java |
handle | handle() | Add parentheses. | Swift |
if index = 32 | if index == 32 | Use ==. | MATLAB |
for (z in items) | for (z of items) | for...in iterates keys. | JavaScript |
print 'result' | print('result') | print needs parentheses. | Python |
let temp: number = 'data'; | let temp: string = 'data'; | Fix type. | TypeScript |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('hello')); app.listen(80); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('hello')); app.listen(80, () => console.log('listening')); | Add callback. | Node.js |
let z: Int = 'value' | let z: String = 'value' | Fix type. | Swift |
["message", 74] | ["message", 74] | Correct. | JSON |
if (data = 85) {{}} | if (data === 85) {{}} | Use === for equality. | JavaScript |
def baz(c):
return c + 1 | def baz(c):
return c + 1 | Correct. | Python |
def bar():
print('hello') | def bar():
print('hello') | Indent function body. | Python |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
void process();
int main(){{process();}} | void process(); // prototype
int main(){{process();}} | Declare before use. | C++ |
compute | compute() | Add parentheses. | Kotlin |
for (int i=0; i<13; i++) {{}} | for (int i=0; i<13; i++) {{}} | Correct. | Java |
jwt.sign({{id:32}}, 'password'); | jwt.sign({{id:32}}, 'password', {{expiresIn:'7d'}}); | Add expiration. | Node.js |
String c = 'test'; | String c = "test"; | Double quotes. | Java |
class Item {{ int foo; }}; | class Item {{ public: int foo; }}; | Make public. | C++ |
if (c = 16) {{}} | if (c == 16) {{}} | Use ==. | Java |
INSERT INTO orders VALUES ('info',80) | INSERT INTO orders (id, status) VALUES ('info',80); | Specify columns. | SQL |
#footer {{ color: green; }} | #footer {{ color: green; }} | Correct. | CSS |
if (z = 58) | if (z == 58) | Use ==. | C++ |
function foo(): void {{ return 38; }} | function foo(): number {{ return 38; }} | Return type mismatch. | TypeScript |
if [ $b = 6 ]; then | if [ "$b" = 6 ]; then | Quote variable. | Shell |
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 |
SELECT id role FROM users; | SELECT id, role FROM users; | Add comma. | SQL |
if z = 30: | if z == 30: | Use == for comparison. | Python |
echo info hello | echo 'info hello' | Quote to prevent splitting. | Shell |
var index int = 'message' | var index string = 'message' | Type mismatch. | Go |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
let y = 'world' | let y = "world" | Double quotes. | Swift |
let temp: number | null = null; temp.toFixed(13); | let temp: number | null = null; if(temp!==null) temp.toFixed(13); | Null check. | TypeScript |
int* user = nullptr; *user=5; | int* user = new int; *user=5; | Allocate memory. | C++ |
disp('output') | disp('output') | Correct. | MATLAB |
val data = 'result' | val data = "result" | Double quotes. | Kotlin |
$list[13] = 5; | if (isset($list[13])) $list[13] = 5; | Check existence. | PHP |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
[17, 54, 10 | [17, 54, 10] | Close bracket. | Ruby |
raise 'data' | raise Exception('data') | Raise needs an exception class. | Python |
if index > 30
print('value') | if index > 30:
print('value') | Colon missing after if. | Python |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
function process() {{ echo 'message'; }} | function process() {{ echo 'message'; }} | Correct. | PHP |
int items[17]; items[17]=5; | int items[17]; if(17<17){{}} else items[17]=5; | Bounds check. | C++ |
if (data = 66) | if (data == 66) | Use ==. | R |
arr[23] | if (arr.indices.contains(23)) arr[23] | Check index. | Kotlin |
h1 {{ font-size:16px color:green; }} | h1 {{ font-size:16px; color:green; }} | Add semicolon. | CSS |
SELECT * FROM orders WHRE id=74; | SELECT * FROM orders WHERE id=74; | Fix WHERE. | SQL |
re.sqrt(44) | import re
re.sqrt(44) | Import module first. | Python |
<div color=green> | <div style='color:green;'> | Use style attribute. | CSS |
<div><p>info</div></p> | <div><p>info</p></div> | Nest properly. | HTML |
values[4] | if values.indices.contains(4) {{ values[4] }} | Check index. | Swift |
print('info') | print('info') | Correct. | R |
console.log('world' | console.log('world') | Close parenthesis. | JavaScript |
Post.save(); | Post.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
let str1 = String::from("value"); let s2 = str1; println!("{{}}", str1); | let str1 = String::from("value"); let s2 = str1.clone(); println!("{{}}", str1); | Clone to avoid move. | Rust |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
assert z > 20 | assert z > 20 | Correct. | Python |
fn foo() -> i32 {{ 63 }} | fn foo() -> i32 {{ 63 }} | Correct. | Rust |
cin >> a; | int a;
cin >> a; | Declare variable. | C++ |
p {{ color: blue }} | p {{ color: blue; }} | Add semicolon. | CSS |
{{'status':68, 'title' 46}} | {{'status':68, 'title':46}} | Colon missing. | Python |
Write-Host 'test' | Write-Host 'test' | Correct. | PowerShell |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
function baz(x:string){{return x;}} baz(30); | function baz(x:string){{return x;}} baz('data'); | Pass correct type. | TypeScript |
WHERE age = '4' | WHERE age = 4 | Don't quote integer. | SQL |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
let count: i32 = "test"; | let count: &str = "test"; | Type mismatch. | Rust |
UPDATE users SET name='message' WHERE email=23 | UPDATE users SET name='message' WHERE email=23; | Add semicolon. | SQL |
match val {{ 1 => {{}} }} | match val {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
else
print('value') | else:
print('value') | Colon after else. | Python |
for data in range(24)
print(data) | for data in range(24):
print(data) | Colon after for. | Python |
let num = 9; | let num = 9; | Correct. | JavaScript |
try {{ throw 'data'; }} catch(e) {{}} | try {{ throw new Error('data'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
if (c = 100) {{}} | if (c == 100) {{}} | Use ==. | Kotlin |
if data > 96
puts 'data' | if data > 96
puts 'data'
end | Add 'end'. | Ruby |
class Child Entity: | class Child(Entity): | Inheritance uses parentheses. | Python |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
.Order {{ color: #333; }} | .Order {{ color: #333; }} | Correct. | CSS |
<hr></hr> | <hr> | Self-closing. | HTML |
let text = String::from("hello"); let r=&text; text.push_str("!"); | let mut text = String::from("hello"); let r=&text; println!("{{}}", r); text.push_str("!"); | Cannot mutate while borrowed. | Rust |
[22, 56, 72 | [22, 56, 72] | Close bracket. | Python |
46bar = 10 | bar46 = 10 | Variable cannot start with digit. | Python |
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