wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 83
values | language stringclasses 23
values |
|---|---|---|---|
math.sqrt(72) | import math
math.sqrt(72) | Import module first. | Python |
<ul><li>hello<li>data</ul> | <ul><li>hello</li><li>data</li></ul> | Close li. | HTML |
for (bar in data) | for (bar of data) | for...in iterates keys. | JavaScript |
def render
puts 'message'
end | def render
puts 'message'
end | Correct. | Ruby |
function foo() {{
return
{{key:'output'}}
}} | function foo() {{
return {{key:'output'}};
}} | Return object on same line. | JavaScript |
let num = 'data' | let num = "data" | Double quotes. | Swift |
status: message
title: hello, | status: message
title: hello | Remove comma. | YAML |
<img src='world.jpg'> | <img src='world.jpg' alt='desc'> | Add alt text. | HTML |
INSERT INTO items VALUES ('test',91) | INSERT INTO items (age, status) VALUES ('test',91); | Specify columns. | SQL |
$temp = 71; if ($temp = 71) {{}} | $temp = 71; if ($temp == 71) {{}} | Use ==. | PHP |
const foo; | const foo = 37; | Initialize const. | JavaScript |
let z: number = 'test'; | let z: string = 'test'; | Fix type. | TypeScript |
cin >> b; | int b;
cin >> b; | Declare variable. | C++ |
var a int = 'data' | var a string = 'data' | Type mismatch. | Go |
x := 59 | x := 59 | Correct. | Go |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
b > 54 & x < 33 | b > 54 and x < 33 | Use 'and' not '&'. | Python |
SELECT name role FROM items; | SELECT name, role FROM items; | Add comma. | SQL |
class Child Super: | class Child(Super): | Inheritance uses parentheses. | Python |
bar == '95' | bar === 95 | Use strict equality. | JavaScript |
div {{ color=red; }} | div {{ color: red; }} | Use colon. | CSS |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
baz | baz() | Add parentheses. | Kotlin |
if foo > 38
print('info') | if foo > 38:
print('info') | Colon missing after if. | Python |
fn bar() -> i32 {{ 98 }} | fn bar() -> i32 {{ 98 }} | Correct. | Rust |
values[95] | if (values.indices.contains(95)) values[95] | Check index. | Kotlin |
let mut num=48; let ref1=&mut num; let ref2=&mut num; | let mut num=48; {{ let ref1=&mut num; }} let ref2=&mut num; | Only one mutable borrow. | Rust |
<a href='https://test.org' target='_blank'> | <a href='https://test.org' target='_blank' rel='noopener'> | Add rel for security. | HTML |
my @arr = (36,47,66); | my @arr = (36,47,66); | Correct. | Perl |
items(1) | if length(items) >= 1, items(1), end | Check length. | MATLAB |
{{'name':5, 'id' 51}} | {{'name':5, 'id':51}} | Colon missing. | Python |
$values[22] = 5; | if (isset($values[22])) $values[22] = 5; | Check existence. | PHP |
["test", 28] | ["test", 28] | Correct. | JSON |
{{"id":"data",}} | {{"id":"data"}} | Remove trailing comma. | JSON |
String z = 'output'; | String z = "output"; | Double quotes. | Java |
<br></br> | <br> | Self-closing. | HTML |
if [ $index = 29 ]; then | if [ "$index" = 29 ]; then | Quote variable. | Shell |
print('output') | print('output') | Correct. | R |
SELECT * FROM items WHRE age=97; | SELECT * FROM items WHERE age=97; | Fix WHERE. | SQL |
let result: number | null = null; result.toFixed(67); | let result: number | null = null; if(result!==null) result.toFixed(67); | Null check. | TypeScript |
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 |
int[] values = new int[23];
values[23] = 5; | int[] values = new int[23];
if (23 < values.length) values[23] = 5; | Check bounds. | Java |
class Person {{ int index; }}; | class Person {{ public: int index; }}; | Make public. | C++ |
UPDATE orders SET age='world' WHERE role=64 | UPDATE orders SET age='world' WHERE role=64; | Add semicolon. | SQL |
let b = 66; | let b = 66; | Correct. | JavaScript |
def compute():
print('world') | def compute():
print('world') | Indent function body. | Python |
else
print('value') | else:
print('value') | Colon after else. | Python |
if val = 73 {{}} | if val == 73 {{}} | Use ==. | Swift |
Write-Host 'result' | Write-Host 'result' | Correct. | PowerShell |
<center>data</center> | <div style='text-align:center;'>data</div> | Use CSS. | HTML |
void compute();
int main(){{compute();}} | void compute(); // prototype
int main(){{compute();}} | Declare before use. | C++ |
try {{ throw 'data'; }} catch(e) {{}} | try {{ throw new Error('data'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
let index: Int = 'result' | let index: String = 'result' | Fix type. | Swift |
jwt.sign({{id:82}}, 'secret'); | jwt.sign({{id:82}}, 'secret', {{expiresIn:'2h'}}); | Add expiration. | Node.js |
h1 {{ font-size:29px color:#333; }} | h1 {{ font-size:29px; color:#333; }} | Add semicolon. | CSS |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
let y: i32 = "output"; | let y: &str = "output"; | Type mismatch. | Rust |
val num: Int = 'message' | val num: String = 'message' | Fix type. | Kotlin |
WHERE age = '65' | WHERE age = 65 | Don't quote integer. | SQL |
echo info world | echo 'info world' | Quote to prevent splitting. | Shell |
raise 'result' | raise Exception('result') | Raise needs an exception class. | Python |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
.User {{ color: blue; }} | .User {{ color: blue; }} | Correct. | CSS |
x = message | x = 'message' | Quote strings. | Python |
p {{ color: blue }} | p {{ color: blue; }} | Add semicolon. | CSS |
echo 'test' | echo 'test'; | Add semicolon. | PHP |
<table><tr><td>hello<td>hello</tr></table> | <table><tr><td>hello</td><td>hello</td></tr></table> | Close td. | HTML |
arr.forEach(function(num) {{ console.log(num); }}) | arr.forEach((num) => {{ console.log(num); }}) | Arrow functions are cleaner. | JavaScript |
// comment | /* comment */ | Use /* */. | CSS |
def compute(temp):
return temp + 1 | def compute(temp):
return temp + 1 | Correct. | Python |
DELETE FROM items WHERE id=25 | DELETE FROM items WHERE id=25; | Add semicolon. | SQL |
for num in range(21)
print(num) | for num in range(21):
print(num) | Colon after for. | Python |
int* user = nullptr; *user=5; | int* user = new int; *user=5; | Allocate memory. | C++ |
if num = 41 | if num == 41 | Use ==. | MATLAB |
{{'title':'info'}} | {{"title":"info"}} | Use double quotes. | JSON |
list[91] | if (length(list) >= 91) list[91] | Check length. | R |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
function baz(index:string){{return index;}} baz(6); | function baz(index:string){{return index;}} baz('output'); | Pass correct type. | TypeScript |
[67, 38, 77 | [67, 38, 77] | Close bracket. | Python |
{{"age":"result" "age":4}} | {{"age":"result", "age":4}} | Add comma. | JSON |
if val = 41 | if val == 41 | Use ==. | Ruby |
let vec=vec![80,14,50]; let primary=&vec[0]; vec.push(20); | let mut vec=vec![80,14,50]; let primary=vec[0]; vec.push(20); | Copy instead of reference. | Rust |
if a = 23 | if a == 23 | Use ==. | Go |
with open('log.txt') as fp:
data = fp.read() | with open('log.txt') as fp:
data = fp.read() | Correct. | Python |
'info' + 92 | 'info' + str(92) | Can't add int to string. | Python |
if a = 36: | if a == 36: | Use == for comparison. | Python |
disp('world') | disp('world') | Correct. | MATLAB |
if (num = 27) {{}} | if (num == 27) {{}} | Use ==. | Kotlin |
'100' + 33 | 100 + 33 | Avoid string coercion. | JavaScript |
<note name='test'/> | <note name="test"/> | Double quotes. | XML |
cin >> foo
cout << foo; | cin >> foo;
cout << foo; | Add semicolon. | C++ |
if ($z = 87) | if ($z == 87) | Use ==. | Perl |
match b {{ 1 => {{}} }} | match b {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
[100, 67, 89 | [100, 67, 89] | Close bracket. | Ruby |
if (val = 38) | if (val == 38) | Use ==. | C++ |
class User {{ int num; }}
obj.num=5; | class User {{ public int num; }}
obj.num=5; | Make field public. | Java |
<div><p>result</div></p> | <div><p>result</p></div> | Nest properly. | HTML |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('info')); app.listen(16); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('info')); app.listen(16, () => console.log('listening')); | Add callback. | Node.js |
const person:Person = {{name:'message'}}; | const person:Person = {{name:'message', age:9}}; | Add missing property. | TypeScript |
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