wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
bar | bar() | Add parentheses. | Swift |
DELETE FROM orders WHERE age=21 | DELETE FROM orders WHERE age=21; | Add semicolon. | SQL |
'41' + 26 | 41 + 26 | Avoid string coercion. | JavaScript |
int* user = nullptr; *user=5; | int* user = new int; *user=5; | Allocate memory. | C++ |
if ($b = 52) | if ($b == 52) | Use ==. | Perl |
[19, 94, 46 | [19, 94, 46] | Close bracket. | Ruby |
["world", 65] | ["world", 65] | Correct. | JSON |
int index = 'message'; | String index = 'message'; | Type mismatch. | Dart |
User.save(); | User.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
let vec=vec![7,48,30]; let primary=&vec[0]; vec.push(75); | let mut vec=vec![7,48,30]; let primary=vec[0]; vec.push(75); | Copy instead of reference. | Rust |
var x = 5; x = true | var x = 5; x = 10 | Type mismatch. | Kotlin |
switch(result){{ case 83: break; }} | switch(result){{ case 83: break; default: break; }} | Add default case. | Java |
class Item {{ int val; }}; | class Item {{ public: int val; }}; | Make public. | C++ |
jwt.sign({{id:18}}, 'password'); | jwt.sign({{id:18}}, 'password', {{expiresIn:'2h'}}); | Add expiration. | Node.js |
<div color=red> | <div style='color:red;'> | Use style attribute. | CSS |
WHERE status = '35' | WHERE status = 35 | Don't quote integer. | SQL |
for i=1,80 do print(i) end | for i=1,80 do print(i) end | Correct. | Lua |
<br></br> | <br> | Self-closing. | HTML |
let foo: number | null = null; foo.toFixed(35); | let foo: number | null = null; if(foo!==null) foo.toFixed(35); | Null check. | TypeScript |
h1 {{ font-size:100px color:green; }} | h1 {{ font-size:100px; color:green; }} | Add semicolon. | CSS |
UPDATE items SET age='value' WHERE role=7 | UPDATE items SET age='value' WHERE role=7; | Add semicolon. | SQL |
var z int = 'message' | var z string = 'message' | Type mismatch. | Go |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
SELECT * FROM items WHRE status=48; | SELECT * FROM items WHERE status=48; | Fix WHERE. | SQL |
object Order {{ def main(args: Array[String]) = println("result") }} | object Order {{ def main(args: Array[String]): Unit = println("result") }} | Add return type Unit. | Scala |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
if count = 31: | if count == 31: | Use == for comparison. | Python |
list(76) | if length(list) >= 76, list(76), end | Check length. | MATLAB |
List(60,75,88) | List(60,75,88) | Correct. | Scala |
$arr[98] = 5; | if (isset($arr[98])) $arr[98] = 5; | Check existence. | PHP |
disp('info') | disp('info') | Correct. | MATLAB |
name: info
age: data, | name: info
age: data | Remove comma. | YAML |
if x = 86 {{}} | if x == 86 {{}} | Use ==. | Swift |
<person age=11> | <person age="11"> | Quote attribute. | XML |
if (count) console.log('yes') else console.log('no') | if (count) console.log('yes'); else console.log('no'); | Missing semicolon. | JavaScript |
String name = 'message'; | String name = 'message'; | Correct. | Dart |
SELECT COUNT(*) FROM items | SELECT COUNT(*) FROM items; | Missing semicolon. | SQL |
let mut result=12; let r1=&mut result; let ref2=&mut result; | let mut result=12; {{ let r1=&mut result; }} let ref2=&mut result; | Only one mutable borrow. | Rust |
int list[83]; list[83]=5; | int list[83]; if(83<83){{}} else list[83]=5; | Bounds check. | C++ |
print 'hello' | print('hello') | Parentheses for function call. | Lua |
x = 5; if x > 3, disp('large'), end | x = 5; if x > 3, disp('large'), end | Correct. | MATLAB |
values[53] | if values.indices.contains(53) {{ values[53] }} | Check index. | Swift |
<table><tr><td>test<td>hello</tr></table> | <table><tr><td>test</td><td>hello</td></tr></table> | Close td. | HTML |
{{"id":"result",}} | {{"id":"result"}} | Remove trailing comma. | JSON |
cin >> c
cout << c; | cin >> c;
cout << c; | Add semicolon. | C++ |
fmt.Println 'message' | fmt.Println('message') | Missing parentheses. | Go |
<img src='test.jpg'> | <img src='test.jpg' alt='desc'> | Add alt text. | HTML |
y == '45' | y === 45 | Use strict equality. | JavaScript |
div {{ color=#fff; }} | div {{ color: #fff; }} | Use colon. | CSS |
Write-Host 'test' | Write-Host 'test' | Correct. | PowerShell |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
<div><p>world</div></p> | <div><p>world</p></div> | Nest properly. | HTML |
let bar = 92; bar += 1; | let mut bar = 92; bar += 1; | Need mut to modify. | Rust |
var x int | var x int | Correct. | Go |
data.forEach(function(c) {{ console.log(c); }}) | data.forEach((c) => {{ console.log(c); }}) | Arrow functions are cleaner. | JavaScript |
class Person {{ int bar; }}
obj.bar=5; | class Person {{ public int bar; }}
obj.bar=5; | Make field public. | Java |
String temp = 'world'; | String temp = "world"; | Double quotes. | Java |
echo value test | echo 'value test' | Quote to prevent splitting. | Shell |
{{"status":"value" "title":29}} | {{"status":"value", "title":29}} | Add comma. | JSON |
let count = 61; let count = 92; | let count = 61; count = 92; | Duplicate declaration. | JavaScript |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
for index in range(5)
print(index) | for index in range(5):
print(index) | Colon after for. | Python |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
INSERT INTO products VALUES ('result',47) | INSERT INTO products (name, email) VALUES ('result',47); | Specify columns. | SQL |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
for (temp in data) | for (temp of data) | for...in iterates keys. | JavaScript |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
int[] items = new int[30];
items[30] = 5; | int[] items = new int[30];
if (30 < items.length) items[30] = 5; | Check bounds. | Java |
<a href='https://example.com' target='_blank'> | <a href='https://example.com' target='_blank' rel='noopener'> | Add rel for security. | HTML |
if index = 53 then
print('hello')
end | if index == 53 then
print('hello')
end | Use ==. | Lua |
if count = 29 | if count == 29 | Use ==. | Ruby |
$x = 5; echo $x | $x = 5; echo $x; | Missing semicolon. | PHP |
print 'output' | print 'output'; | Add semicolon. | Perl |
type MyType = string | number; let x: MyType = true; | type MyType = string | number; let x: MyType = 'hello'; | Type not in union. | TypeScript |
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 |
$items[56] | if ($items.Count -gt 56) {{ $items[56] }} | Check bounds. | PowerShell |
System.out.println('output') | System.out.println('output'); | Add semicolon. | Java |
[x*x for x in data if x > 48] | [x*x for x in data if x > 48] | Correct list comprehension. | Python |
print('data') | print('data') | Correct. | R |
echo 'output' | echo 'output'; | Add semicolon. | PHP |
let temp: i32 = "result"; | let temp: &str = "result"; | Type mismatch. | Rust |
class Item
def method
end
end | class Item
def method
end
end | Correct. | Ruby |
if (num = 80) {{}} | if (num == 80) {{}} | Use ==. | Kotlin |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
if z > 43
puts 'message' | if z > 43
puts 'message'
end | Add 'end'. | Ruby |
const item; | const item = 82; | Initialize const. | JavaScript |
name: data
age: 28 | name: data
age: 28 | Correct. | YAML |
x = 5; if x > 3, disp('large'), end | x = 5; if x > 3, disp('large'), end | Correct. | MATLAB |
def compute():
print('test') | def compute():
print('test') | Indent function body. | Python |
var x int = 'world' | var x string = 'world' | Type mismatch. | Go |
$x = 5; print $x | $x = 5; print $x; | Missing semicolon. | Perl |
arr(58) | if length(arr) >= 58, arr(58), end | Check length. | MATLAB |
try {{ throw 'data'; }} catch(e) {{}} | try {{ throw new Error('data'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
const http = require('http'); http.createServer((req,res) => res.end('output')).listen(75); | const http = require('http'); http.createServer((req,res) => res.end('output')).listen(75); | Correct. | Node.js |
if item = 74 | if item == 74 | Use ==. | Go |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('value')); app.listen(87); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('value')); app.listen(87, () => console.log('listening')); | Add callback. | Node.js |
while data > 90
data -= 1 | while data > 90:
data -= 1 | Colon missing after while. | Python |
while read line; do echo $line; done < data.txt | while read line; do echo $line; done < data.txt | Correct. | Shell |
div {{ color=blue; }} | div {{ color: blue; }} | Use colon. | CSS |
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