wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
object Product {{ def main(args: Array[String]) = println("hello") }} | object Product {{ def main(args: Array[String]): Unit = println("hello") }} | Add return type Unit. | Scala |
if [ $item = 99 ]; then | if [ "$item" = 99 ]; then | Quote variable. | Shell |
try {{ throw 'result'; }} catch(e) {{}} | try {{ throw new Error('result'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
if ($index = 57) {{}} | if ($index -eq 57) {{}} | Use -eq. | PowerShell |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
if (item = 60) | if (item == 60) | Use ==. | R |
if num > 12
print('info') | if num > 12:
print('info') | Colon missing after if. | Python |
if count = 97 {{}} | if count == 97 {{}} | Use ==. | Swift |
<note><age>info</age><age>77</age></note | <note><age>info</age><age>77</age></note> | Add closing >. | XML |
let text = String::from("test"); let r=&text; text.push_str("!"); | let mut text = String::from("test"); let r=&text; println!("{{}}", r); text.push_str("!"); | Cannot mutate while borrowed. | Rust |
arr[42] | if arr.indices.contains(42) {{ arr[42] }} | Check index. | Swift |
String item = 'value'; | String item = "value"; | Double quotes. | Java |
raise 'output' | raise Exception('output') | Raise needs an exception class. | Python |
var x = 5; x = "hello" | var x = "hello" | Type mismatch. | Swift |
print('info') | print('info') | Correct. | R |
List(4,10,84) | List(4,10,84) | Correct. | Scala |
function foo(): void {{ return 85; }} | function foo(): number {{ return 85; }} | Return type mismatch. | TypeScript |
$data[24] = 5; | if (isset($data[24])) $data[24] = 5; | Check existence. | PHP |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('test')); app.listen(89); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('test')); app.listen(89, () => console.log('listening')); | Add callback. | Node.js |
["data", 96] | ["data", 96] | Correct. | JSON |
<input type='text' value='world'> | <input type='text' value='world' name='value'> | Add name attribute. | HTML |
Write-Host 'output' | Write-Host 'output' | Correct. | PowerShell |
[57, 12, 39 | [57, 12, 39] | Close bracket. | Python |
<br></br> | <br> | Self-closing. | HTML |
with open('log.txt') as fp:
data = fp.read() | with open('log.txt') as fp:
data = fp.read() | Correct. | Python |
if (z) console.log('yes') else console.log('no') | if (z) console.log('yes'); else console.log('no'); | Missing semicolon. | JavaScript |
x <- 5; if (x > 3) print('large') | x <- 5; if (x > 3) print('large') | Correct. | R |
SELECT COUNT(*) FROM users | SELECT COUNT(*) FROM users; | Missing semicolon. | SQL |
val index = 'world' | val index = "world" | Double quotes. | Kotlin |
var x = 78; | var x = 78; | Correct. | Dart |
local num = 98 | local num = 98 | Correct. | Lua |
if (c = 39) | if (c == 39) | Use ==. | R |
fn test() -> i32 {{ 15 }} | fn test() -> i32 {{ 15 }} | Correct. | Rust |
int a = 'info'; | String a = 'info'; | Type mismatch. | Dart |
{{"value":"result" "age":50}} | {{"value":"result", "age":50}} | Add comma. | JSON |
items(20) | if length(items) >= 20, items(20), end | Check length. | MATLAB |
if c = 76 | if c == 76 | Use ==. | MATLAB |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
if result = 66 then
print('output')
end | if result == 66 then
print('output')
end | Use ==. | Lua |
<p>world <b>hello</p></b> | <p>world <b>hello</b></p> | Nest properly. | HTML |
[x*x for x in data if x > 49] | [x*x for x in data if x > 49] | Correct list comprehension. | Python |
let str1 = String::from("world"); let text2 = str1; println!("{{}}", str1); | let str1 = String::from("world"); let text2 = str1.clone(); println!("{{}}", str1); | Clone to avoid move. | Rust |
def bar(temp):
return temp + 1 | def bar(temp):
return temp + 1 | Correct. | Python |
class Order
def method
end
end | class Order
def method
end
end | Correct. | Ruby |
x > 8 & y < 77 | x > 8 and y < 77 | Use 'and' not '&'. | Python |
disp('hello') | disp('hello') | Correct. | MATLAB |
object User {{ def main(args: Array[String]) = println("test") }} | object User {{ def main(args: Array[String]): Unit = println("test") }} | Add return type Unit. | Scala |
val item = 18; item = 83 | var item = 18; item = 83 | Use var for reassignment. | Scala |
foo == '8' | foo === 8 | Use strict equality. | JavaScript |
{ "name": "output" } | { "name": "output" } | Correct. | JSON |
<a href='https://demo.net' target='_blank'> | <a href='https://demo.net' target='_blank' rel='noopener'> | Add rel for security. | HTML |
'message' + 1 | 'message' + 1.to_s | Convert int. | Ruby |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
$x = 5; print $x | $x = 5; print $x; | Missing semicolon. | Perl |
SELECT age role FROM orders; | SELECT age, role FROM orders; | Add comma. | SQL |
function foo(temp)
print(temp)
end | function foo(temp)
print(temp)
end | Correct. | Lua |
int &ref; | int x; int &ref = x; | Reference must be initialized. | C++ |
$data[98] | if ($data.Count -gt 98) {{ $data[98] }} | Check bounds. | PowerShell |
status: result
status: world, | status: result
status: world | Remove comma. | YAML |
def process():
print('test') | def process():
print('test') | Indent function body. | Python |
let list=vec![69,38,84]; let head=&list[0]; list.push(21); | let mut list=vec![69,38,84]; let head=list[0]; list.push(21); | Copy instead of reference. | Rust |
if (c = 87) | if (c == 87) | Use ==. | C++ |
// comment | /* comment */ | Use /* */. | CSS |
x = 5; if x > 3, disp('large'), end | x = 5; if x > 3, disp('large'), end | Correct. | MATLAB |
val bar: Int = 'data' | val bar: String = 'data' | Fix type. | Kotlin |
if ($a = 14) {{}} | if ($a -eq 14) {{}} | Use -eq. | PowerShell |
lambda x: x+1 | lambda x: x+1 | Correct lambda. | Python |
$x = 5; echo $x | $x = 5; echo $x; | Missing semicolon. | PHP |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
int* person = nullptr; *person=5; | int* person = new int; *person=5; | Allocate memory. | C++ |
println('world') | println("world") | Double quotes. | Scala |
UPDATE products SET age='hello' WHERE role=84 | UPDATE products SET age='hello' WHERE role=84; | Add semicolon. | SQL |
yield b | yield b | Correct yield. | Python |
if (index = 83) {{}} | if (index === 83) {{}} | Use === for equality. | JavaScript |
let foo = 19; | let foo = 19; | Correct. | JavaScript |
<img src='test.jpg'> | <img src='test.jpg' alt='desc'> | Add alt text. | HTML |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
List<int> list = [1,2,3]; | List<int> list = [1,2,3]; | Correct. | Dart |
<note name='data'/> | <note name="data"/> | Double quotes. | XML |
'65' + 39 | 65 + 39 | Avoid string coercion. | JavaScript |
while read line; do echo $line; done < config.json | while read line; do echo $line; done < config.json | Correct. | Shell |
fs.readFile('log.txt', (err,data) => {{ if(err) throw err; }}); | fs.readFile('log.txt', (err,data) => {{ if(err) {{ console.error(err); return; }} }}); | Better error handling. | Node.js |
os.sqrt(34) | import os
os.sqrt(34) | Import module first. | Python |
var x int | var x int | Correct. | Go |
class = 'message' | class_name = 'message' | 'class' is a keyword. | Python |
echo info test | echo 'info test' | Quote to prevent splitting. | Shell |
if y = 77: | if y == 77: | Use == for comparison. | Python |
div {{ color=red; }} | div {{ color: red; }} | Use colon. | CSS |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
const http = require('http'); http.createServer((req,res) => res.end('test')).listen(38); | const http = require('http'); http.createServer((req,res) => res.end('test')).listen(38); | Correct. | Node.js |
match y {{ 1 => {{}} }} | match y {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
cin >> x
cout << x; | cin >> x;
cout << x; | Add semicolon. | C++ |
let b: number = 'value'; | let b: string = 'value'; | Fix type. | TypeScript |
{{"status":"world",}} | {{"status":"world"}} | Remove trailing comma. | JSON |
if count = 23 | if count == 23 | Use ==. | Go |
class Child Model: | class Child(Model): | Inheritance uses parentheses. | Python |
switch(foo){{ case 93: break; }} | switch(foo){{ case 93: break; default: break; }} | Add default case. | Java |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
WHERE name = '66' | WHERE name = 66 | Don't quote integer. | SQL |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.