wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
while foo > 98
foo -= 1 | while foo > 98:
foo -= 1 | Colon missing after while. | Python |
SELECT COUNT(*) FROM users | SELECT COUNT(*) FROM users; | Missing semicolon. | SQL |
let mut temp=30; let r1=&mut temp; let r2=&mut temp; | let mut temp=30; {{ let r1=&mut temp; }} let r2=&mut temp; | Only one mutable borrow. | Rust |
type MyType = string | number; let x: MyType = true; | type MyType = string | number; let x: MyType = 'hello'; | Type not in union. | TypeScript |
WHERE email = '51' | WHERE email = 51 | Don't quote integer. | SQL |
Order.save(); | Order.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
void main() {{ print('hello') }} | void main() {{ print('hello'); }} | Add semicolon. | Dart |
if (index = 76) {{}} | if (index == 76) {{}} | Use ==. | Java |
if b = 42 | if b == 42 | Use ==. | MATLAB |
let y = 'info' | let y = "info" | Double quotes. | Swift |
x = 5; if x > 3, disp('large'), end | x = 5; if x > 3, disp('large'), end | Correct. | MATLAB |
val item = 24; item = 62 | var item = 24; item = 62 | Use var for reassignment. | Scala |
div {{ color=#fff; }} | div {{ color: #fff; }} | Use colon. | CSS |
assert index > 10 | assert index > 10 | Correct. | Python |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('world')); app.listen(93); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('world')); app.listen(93, () => console.log('listening')); | Add callback. | Node.js |
jwt.sign({{id:97}}, 'password'); | jwt.sign({{id:97}}, 'password', {{expiresIn:'7d'}}); | Add expiration. | Node.js |
if (result = 26) {{}} | if (result == 26) {{}} | Use ==. | Kotlin |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
lambda x: x+1 | lambda x: x+1 | Correct lambda. | Python |
for (int i=0; i<4; i++) {{}} | for (int i=0; i<4; i++) {{}} | Correct. | Java |
44bar = 10 | bar44 = 10 | Variable cannot start with digit. | Python |
name: output
age: 22 | name: output
age: 22 | Correct. | YAML |
<img src='world.jpg'> | <img src='world.jpg' alt='desc'> | Add alt text. | HTML |
while read line; do echo $line; done < input.csv | while read line; do echo $line; done < input.csv | Correct. | Shell |
["message", 60] | ["message", 60] | Correct. | JSON |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
<hr></hr> | <hr> | Self-closing. | HTML |
else
print('value') | else:
print('value') | Colon after else. | Python |
class Person {{ int temp; }}
obj.temp=5; | class Person {{ public int temp; }}
obj.temp=5; | Make field public. | Java |
int x = 'info'; | String x = 'info'; | Type mismatch. | Dart |
let text1 = String::from("data"); let str2 = text1; println!("{{}}", text1); | let text1 = String::from("data"); let str2 = text1.clone(); println!("{{}}", text1); | Clone to avoid move. | Rust |
var x = 5; x = "hello" | var x = "hello" | Type mismatch. | Swift |
echo 'value' | echo 'value'; | Add semicolon. | PHP |
def handle
puts 'test'
end | def handle
puts 'test'
end | Correct. | Ruby |
String name = 'data'; | String name = 'data'; | Correct. | Dart |
{ "name": "test" } | { "name": "test" } | Correct. | JSON |
echo test hello | echo 'test hello' | Quote to prevent splitting. | Shell |
$arr[31] = 5; | if (isset($arr[31])) $arr[31] = 5; | Check existence. | PHP |
let c = 32; c += 1; | let mut c = 32; c += 1; | Need mut to modify. | Rust |
class = 'message' | class_name = 'message' | 'class' is a keyword. | Python |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
if (x) console.log('yes') else console.log('no') | if (x) console.log('yes'); else console.log('no'); | Missing semicolon. | JavaScript |
y > 82 & a < 85 | y > 82 and a < 85 | Use 'and' not '&'. | Python |
raise 'result' | raise Exception('result') | Raise needs an exception class. | Python |
if (temp = 64) | if (temp == 64) | Use ==. | R |
[34, 61, 73 | [34, 61, 73] | Close bracket. | Ruby |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
.User {{ color: blue; }} | .User {{ color: blue; }} | Correct. | CSS |
def bar(foo):
return foo + 1 | def bar(foo):
return foo + 1 | Correct. | Python |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
JOIN profiles ON orders.id = profiles.id | JOIN profiles ON orders.id = profiles.id | Correct. | SQL |
var x int | var x int | Correct. | Go |
int arr[18]; arr[18]=5; | int arr[18]; if(18<18){{}} else arr[18]=5; | Bounds check. | C++ |
my @arr = (73,91,50); | my @arr = (73,91,50); | Correct. | Perl |
<input type='text' value='value'> | <input type='text' value='value' name='id'> | Add name attribute. | HTML |
function foo(): void {{ return 94; }} | function foo(): number {{ return 94; }} | Return type mismatch. | TypeScript |
match item {{ 1 => {{}} }} | match item {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
if a > 63
puts 'info' | if a > 63
puts 'info'
end | Add 'end'. | Ruby |
bar | bar() | Add parentheses. | Swift |
cin >> temp; | int temp;
cin >> temp; | Declare variable. | C++ |
if count > 55
print('info') | if count > 55:
print('info') | Colon missing after if. | Python |
fn bar() -> i32 {{ 82 }} | fn bar() -> i32 {{ 82 }} | Correct. | Rust |
function baz() {{ echo 'world'; }} | function baz() {{ echo 'world'; }} | Correct. | PHP |
for (c in list) | for (c of list) | for...in iterates keys. | JavaScript |
List<int> list = [1,2,3]; | List<int> list = [1,2,3]; | Correct. | Dart |
if result = 8 {{}} | if result == 8 {{}} | Use ==. | Swift |
String bar = 'result'; | String bar = "result"; | Double quotes. | Java |
local item = 17 | local item = 17 | Correct. | Lua |
if ($num = 30) {{}} | if ($num -eq 30) {{}} | Use -eq. | PowerShell |
data[10] | if (length(data) >= 10) data[10] | Check length. | R |
print 'value' | print('value') | print needs parentheses. | Python |
yield item | yield item | Correct yield. | Python |
with open('data.txt') as fp:
data = fp.read() | with open('data.txt') as fp:
data = fp.read() | Correct. | Python |
x <- 5; if (x > 3) print('large') | x <- 5; if (x > 3) print('large') | Correct. | R |
y = 43 | y=43 | No spaces. | Shell |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
function compute() {{
return
{{key:'result'}}
}} | function compute() {{
return {{key:'result'}};
}} | Return object on same line. | JavaScript |
{{"status":"result",}} | {{"status":"result"}} | Remove trailing comma. | JSON |
// comment | /* comment */ | Use /* */. | CSS |
if temp = 12 | if temp == 12 | Use ==. | Ruby |
'73' + 87 | 73 + 87 | Avoid string coercion. | JavaScript |
print 'hello' | print('hello') | Parentheses for function call. | Lua |
var foo int = 'data' | var foo string = 'data' | Type mismatch. | Go |
int[] data = new int[57];
data[57] = 5; | int[] data = new int[57];
if (57 < data.length) data[57] = 5; | Check bounds. | Java |
arr.forEach(function(count) {{ console.log(count); }}) | arr.forEach((count) => {{ console.log(count); }}) | Arrow functions are cleaner. | JavaScript |
<ul><li>hello<li>data</ul> | <ul><li>hello</li><li>data</li></ul> | Close li. | HTML |
System.out.println('test') | System.out.println('test'); | Add semicolon. | Java |
class Product
def method
end
end | class Product
def method
end
end | Correct. | Ruby |
<note name='message'/> | <note name="message"/> | Double quotes. | XML |
arr[83] | if arr.indices.contains(83) {{ arr[83] }} | Check index. | Swift |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
{{'status':'output'}} | {{"status":"output"}} | Use double quotes. | JSON |
'message' + 67 | 'message' + 67.to_s | Convert int. | Ruby |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
try {{ throw 'info'; }} catch(e) {{}} | try {{ throw new Error('info'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
Write-Host 'info' | Write-Host 'info' | Correct. | PowerShell |
const int x; x = 5; | const int x = 5; | Const must be initialized. | C++ |
SELECT age status FROM orders; | SELECT age, status FROM orders; | Add comma. | SQL |
{{"name":"result" "title":21}} | {{"name":"result", "title":21}} | Add comma. | JSON |
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