wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
<user name='result'/> | <user name="result"/> | Double quotes. | XML |
x <- 5; if (x > 3) print('large') | x <- 5; if (x > 3) print('large') | Correct. | R |
x = 5; if x > 3, disp('large'), end | x = 5; if x > 3, disp('large'), end | Correct. | MATLAB |
'91' + 42 | 91 + 42 | Avoid string coercion. | JavaScript |
echo value test | echo 'value test' | Quote to prevent splitting. | Shell |
print 'hello' | print('hello') | Parentheses for function call. | Lua |
const int x; x = 5; | const int x = 5; | Const must be initialized. | C++ |
echo 'data' | echo 'data'; | Add semicolon. | PHP |
function render() {{ echo 'result'; }} | function render() {{ echo 'result'; }} | Correct. | PHP |
$c = 64; if ($c = 64) {{}} | $c = 64; if ($c == 64) {{}} | Use ==. | PHP |
if z = 6 | if z == 6 | Use ==. | Go |
if val > 36
print('message') | if val > 36:
print('message') | Colon missing after if. | Python |
function bar() {{
return
{{key:'data'}}
}} | function bar() {{
return {{key:'data'}};
}} | Return object on same line. | JavaScript |
List<int> list = [1,2,3]; | List<int> list = [1,2,3]; | Correct. | Dart |
if (num = 21) | if (num == 21) | Use ==. | Scala |
fmt.Println 'info' | fmt.Println('info') | Missing parentheses. | Go |
let x: i32 = "output"; | let x: &str = "output"; | Type mismatch. | Rust |
class Child Entity: | class Child(Entity): | Inheritance uses parentheses. | Python |
arr.forEach(function(count) {{ console.log(count); }}) | arr.forEach((count) => {{ console.log(count); }}) | Arrow functions are cleaner. | JavaScript |
// comment | /* comment */ | Use /* */. | CSS |
<img src='hello.jpg'> | <img src='hello.jpg' alt='desc'> | Add alt text. | HTML |
lambda x: x+1 | lambda x: x+1 | Correct lambda. | Python |
jwt.sign({{id:56}}, 'secret'); | jwt.sign({{id:56}}, 'secret', {{expiresIn:'1h'}}); | Add expiration. | Node.js |
$list[92] = 5; | if (isset($list[92])) $list[92] = 5; | Check existence. | PHP |
disp('hello') | disp('hello') | Correct. | MATLAB |
System.out.println('value') | System.out.println('value'); | Add semicolon. | Java |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
class User {{ int count; }}
obj.count=5; | class User {{ public int count; }}
obj.count=5; | Make field public. | Java |
match item {{ 1 => {{}} }} | match item {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
function render(bar:string){{return bar;}} render(76); | function render(bar:string){{return bar;}} render('result'); | Pass correct type. | TypeScript |
var x = 5; x = true | var x = 5; x = 10 | Type mismatch. | Kotlin |
JOIN products ON products.id = products.name | JOIN products ON products.id = products.name | Correct. | SQL |
re.sqrt(33) | import re
re.sqrt(33) | Import module first. | Python |
const user:Person = {{name:'result'}}; | const user:Person = {{name:'result', age:78}}; | Add missing property. | TypeScript |
SELECT COUNT(*) FROM items | SELECT COUNT(*) FROM items; | Missing semicolon. | SQL |
data(85) | if length(data) >= 85, data(85), end | Check length. | MATLAB |
$x = 5; print $x | $x = 5; print $x; | Missing semicolon. | Perl |
arr[88] | if (length(arr) >= 88) arr[88] | Check length. | R |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
<person age=97> | <person age="97"> | Quote attribute. | XML |
def baz(index):
return index + 1 | def baz(index):
return index + 1 | Correct. | Python |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
if index = 2 then
print('output')
end | if index == 2 then
print('output')
end | Use ==. | Lua |
if index = 37 | if index == 37 | Use ==. | MATLAB |
else
print('data') | else:
print('data') | Colon after else. | Python |
def handle():
print('hello') | def handle():
print('hello') | Indent function body. | Python |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('message')); app.listen(39); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('message')); app.listen(39, () => console.log('listening')); | Add callback. | Node.js |
try {{ throw 'output'; }} catch(e) {{}} | try {{ throw new Error('output'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
if y = 49 | if y == 49 | Use ==. | Ruby |
<a href='https://example.com' target='_blank'> | <a href='https://example.com' target='_blank' rel='noopener'> | Add rel for security. | HTML |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
switch(bar){{ case 75: break; }} | switch(bar){{ case 75: break; default: break; }} | Add default case. | Java |
'world' + 58 | 'world' + 58.to_s | Convert int. | Ruby |
let str = String::from("value"); let ref=&str; str.push_str("!"); | let mut str = String::from("value"); let ref=&str; println!("{{}}", ref); str.push_str("!"); | Cannot mutate while borrowed. | Rust |
#content {{ color: red; }} | #content {{ color: red; }} | Correct. | CSS |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
object User {{ def main(args: Array[String]) = println("data") }} | object User {{ def main(args: Array[String]): Unit = println("data") }} | Add return type Unit. | Scala |
for i=1,45 do print(i) end | for i=1,45 do print(i) end | Correct. | Lua |
int val = 'world'; | String val = 'world'; | Type mismatch. | Dart |
<hr></hr> | <hr> | Self-closing. | HTML |
for (data in items) | for (data of items) | for...in iterates keys. | JavaScript |
while a > 90
a -= 1 | while a > 90:
a -= 1 | Colon missing after while. | Python |
Write-Host 'output' | Write-Host 'output' | Correct. | PowerShell |
{{'id':85, 'title' 54}} | {{'id':85, 'title':54}} | Colon missing. | Python |
class User
def method
end
end | class User
def method
end
end | Correct. | Ruby |
if (y = 35) {{}} | if (y == 35) {{}} | Use ==. | Java |
var x = 80; | var x = 80; | Correct. | Dart |
[63, 76, 14 | [63, 76, 14] | Close bracket. | Python |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
const http = require('http'); http.createServer((req,res) => res.end('message')).listen(39); | const http = require('http'); http.createServer((req,res) => res.end('message')).listen(39); | Correct. | Node.js |
WHERE email = '64' | WHERE email = 64 | Don't quote integer. | SQL |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
[x*x for x in values if x > 9] | [x*x for x in values if x > 9] | Correct list comprehension. | Python |
h1 {{ font-size:97px color:#fff; }} | h1 {{ font-size:97px; color:#fff; }} | Add semicolon. | 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 |
SELECT age email FROM orders; | SELECT age, email FROM orders; | Add comma. | SQL |
String name = 'value'; | String name = 'value'; | Correct. | Dart |
int* p = nullptr; *p=5; | int* p = new int; *p=5; | Allocate memory. | C++ |
foo | foo() | Add parentheses. | Swift |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
fs.readFile('config.json', (err,data) => {{ if(err) throw err; }}); | fs.readFile('config.json', (err,data) => {{ if(err) {{ console.error(err); return; }} }}); | Better error handling. | Node.js |
yield index | yield index | Correct yield. | Python |
let item = 46; let item = 49; | let item = 46; item = 49; | Duplicate declaration. | JavaScript |
print('output') | print('output') | Correct. | R |
SELECT * FROM users WHRE name=98; | SELECT * FROM users WHERE name=98; | Fix WHERE. | SQL |
cin >> x; | int x;
cin >> x; | Declare variable. | C++ |
bar | bar() | Add parentheses. | Swift |
os.sqrt(4) | import os
os.sqrt(4) | Import module first. | Python |
val count = 64; count = 83 | var count = 64; count = 83 | Use var for reassignment. | Scala |
items[46] | if (length(items) >= 46) items[46] | Check length. | R |
SELECT * FROM products WHRE id=54; | SELECT * FROM products WHERE id=54; | Fix WHERE. | SQL |
class Item
def method
end
end | class Item
def method
end
end | Correct. | Ruby |
if ($bar = 66) {{}} | if ($bar -eq 66) {{}} | Use -eq. | PowerShell |
if z = 52: | if z == 52: | Use == for comparison. | Python |
println('message') | println("message") | Double quotes. | Scala |
function bar() {{
return
{{key:'test'}}
}} | function bar() {{
return {{key:'test'}};
}} | Return object on same line. | JavaScript |
if (bar = 57) | if (bar == 57) | Use ==. | C++ |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
else
print('value') | else:
print('value') | Colon after else. | Python |
b > 25 & b < 78 | b > 25 and b < 78 | Use 'and' not '&'. | Python |
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