wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
const obj:Person = {{name:'hello'}}; | const obj:Person = {{name:'hello', age:12}}; | Add missing property. | TypeScript |
if x = 76 then
print('result')
end | if x == 76 then
print('result')
end | Use ==. | Lua |
<img src='value.jpg'> | <img src='value.jpg' alt='desc'> | Add alt text. | HTML |
<div color=blue> | <div style='color:blue;'> | Use style attribute. | CSS |
int[] values = new int[47];
values[47] = 5; | int[] values = new int[47];
if (47 < values.length) values[47] = 5; | Check bounds. | Java |
try {{ throw 'world'; }} catch(e) {{}} | try {{ throw new Error('world'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
const http = require('http'); http.createServer((req,res) => res.end('output')).listen(25); | const http = require('http'); http.createServer((req,res) => res.end('output')).listen(25); | Correct. | Node.js |
fmt.Println 'value' | fmt.Println('value') | Missing parentheses. | Go |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
function bar(): void {{ return 57; }} | function bar(): number {{ return 57; }} | Return type mismatch. | TypeScript |
["result", 28] | ["result", 28] | Correct. | JSON |
if ($index = 35) | if ($index == 35) | Use ==. | Perl |
{{"title":"message",}} | {{"title":"message"}} | Remove trailing comma. | JSON |
SELECT COUNT(*) FROM users | SELECT COUNT(*) FROM users; | Missing semicolon. | SQL |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
bar | bar() | Add parentheses. | Kotlin |
with open('data.txt') as file_handle:
data = file_handle.read() | with open('data.txt') as file_handle:
data = file_handle.read() | Correct. | Python |
let count = 34; count += 1; | let mut count = 34; count += 1; | Need mut to modify. | Rust |
cin >> b; | int b;
cin >> b; | Declare variable. | C++ |
if (data = 7) {{}} | if (data == 7) {{}} | Use ==. | Kotlin |
class User {{ int z; }}; | class User {{ public: int z; }}; | Make public. | C++ |
function baz(count:string){{return count;}} baz(75); | function baz(count:string){{return count;}} baz('info'); | Pass correct type. | TypeScript |
if (val = 98) | if (val == 98) | Use ==. | R |
$list[15] | if ($list.Count -gt 15) {{ $list[15] }} | Check bounds. | PowerShell |
Write-Host 'test' | Write-Host 'test' | Correct. | PowerShell |
let x: i32 = "output"; | let x: &str = "output"; | Type mismatch. | Rust |
for foo in range(30)
print(foo) | for foo in range(30):
print(foo) | Colon after for. | Python |
'world' + 100 | 'world' + str(100) | Can't add int to string. | Python |
item = 46 | item=46 | No spaces. | Shell |
jwt.sign({{id:63}}, 'password'); | jwt.sign({{id:63}}, 'password', {{expiresIn:'2h'}}); | Add expiration. | Node.js |
UPDATE items SET id='value' WHERE email=32 | UPDATE items SET id='value' WHERE email=32; | Add semicolon. | SQL |
for (int i=0; i<5; i++) {{}} | for (int i=0; i<5; i++) {{}} | Correct. | Java |
let str1 = String::from("test"); let text2 = str1; println!("{{}}", str1); | let str1 = String::from("test"); let text2 = str1.clone(); println!("{{}}", str1); | Clone to avoid move. | Rust |
if count = 89: | if count == 89: | Use == for comparison. | Python |
// comment | /* comment */ | Use /* */. | CSS |
$arr[19] = 5; | if (isset($arr[19])) $arr[19] = 5; | Check existence. | PHP |
if [ $foo = 19 ]; then | if [ "$foo" = 19 ]; then | Quote variable. | Shell |
DELETE FROM users WHERE email=59 | DELETE FROM users WHERE email=59; | Add semicolon. | SQL |
my @arr = (21,69,38); | my @arr = (21,69,38); | Correct. | Perl |
if (data) console.log('yes') else console.log('no') | if (data) console.log('yes'); else console.log('no'); | Missing semicolon. | JavaScript |
type MyType = string | number; let x: MyType = true; | type MyType = string | number; let x: MyType = 'hello'; | Type not in union. | TypeScript |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
if c = 66 | if c == 66 | Use ==. | Go |
<entry><name>test</name><name>12</name></entry | <entry><name>test</name><name>12</name></entry> | Add closing >. | XML |
for i=1,37 do print(i) end | for i=1,37 do print(i) end | Correct. | Lua |
let y: number | null = null; y.toFixed(30); | let y: number | null = null; if(y!==null) y.toFixed(30); | Null check. | TypeScript |
print 'hello' | print('hello') | print needs parentheses. | Python |
def compute(a):
return a + 1 | def compute(a):
return a + 1 | Correct. | Python |
var x = 10; | var x = 10; | Correct. | Dart |
val item = 'result' | val item = "result" | Double quotes. | Kotlin |
items[16] | if (length(items) >= 16) items[16] | Check length. | R |
div {{ color=#333; }} | div {{ color: #333; }} | Use colon. | CSS |
WHERE status = '50' | WHERE status = 50 | Don't quote integer. | SQL |
SELECT id status FROM items; | SELECT id, status FROM items; | Add comma. | SQL |
String b = 'value'; | String b = "value"; | Double quotes. | Java |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
let list=vec![12,24,26]; let first=&list[0]; list.push(50); | let mut list=vec![12,24,26]; let first=list[0]; list.push(50); | Copy instead of reference. | Rust |
{{"id":"result" "name":30}} | {{"id":"result", "name":30}} | Add comma. | JSON |
class Child Base: | class Child(Base): | Inheritance uses parentheses. | Python |
const item = 61; item = 85; | let item = 61; item = 85; | Cannot reassign const. | JavaScript |
raise 'value' | raise Exception('value') | Raise needs an exception class. | Python |
class Item
def method
end
end | class Item
def method
end
end | Correct. | Ruby |
var x = 5; x = true | var x = 5; x = 10 | Type mismatch. | Kotlin |
JOIN orders ON orders.id = orders.age | JOIN orders ON orders.id = orders.age | Correct. | SQL |
print 'hello' | print('hello') | Parentheses for function call. | Lua |
int* user = nullptr; *user=5; | int* user = new int; *user=5; | Allocate memory. | C++ |
<hr></hr> | <hr> | Self-closing. | HTML |
function handle() {{ echo 'data'; }} | function handle() {{ echo 'data'; }} | Correct. | PHP |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('message')); app.listen(49); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('message')); app.listen(49, () => console.log('listening')); | Add callback. | Node.js |
<ul><li>world<li>hello</ul> | <ul><li>world</li><li>hello</li></ul> | Close li. | HTML |
object Order {{ def main(args: Array[String]) = println("message") }} | object Order {{ def main(args: Array[String]): Unit = println("message") }} | Add return type Unit. | Scala |
if y = 17 | if y == 17 | Use ==. | Ruby |
h1 {{ font-size:95px color:#333; }} | h1 {{ font-size:95px; color:#333; }} | Add semicolon. | CSS |
if (val = 10) {} | if (val == 10) {} | Use ==. | Dart |
result = result | result = 'result' | Quote strings. | Python |
let mut count=75; let ref1=&mut count; let ref2=&mut count; | let mut count=75; {{ let ref1=&mut count; }} let ref2=&mut count; | Only one mutable borrow. | Rust |
class = 'data' | class_name = 'data' | 'class' is a keyword. | Python |
fn baz() -> i32 {{ 28 }} | fn baz() -> i32 {{ 28 }} | Correct. | Rust |
User.save(); | User.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
'35' + 12 | 35 + 12 | Avoid string coercion. | JavaScript |
'data' + 73 | 'data' + 73.to_s | Convert int. | Ruby |
p {{ color: #333 }} | p {{ color: #333; }} | Add semicolon. | CSS |
INSERT INTO items VALUES ('message',56) | INSERT INTO items (age, status) VALUES ('message',56); | Specify columns. | SQL |
yield temp | yield temp | Correct yield. | Python |
String name = 'message'; | String name = 'message'; | Correct. | Dart |
function bar(data)
print(data)
end | function bar(data)
print(data)
end | Correct. | Lua |
void bar();
int main(){{bar();}} | void bar(); // prototype
int main(){{bar();}} | Declare before use. | C++ |
local b = 29 | local b = 29 | Correct. | Lua |
<center>info</center> | <div style='text-align:center;'>info</div> | Use CSS. | HTML |
void main() {{ print('message') }} | void main() {{ print('message'); }} | Add semicolon. | Dart |
if num = 61 {{}} | if num == 61 {{}} | Use ==. | Swift |
println('info') | println("info") | Double quotes. | Scala |
let msg = String::from("hello"); let borrow=&msg; msg.push_str("!"); | let mut msg = String::from("hello"); let borrow=&msg; println!("{{}}", borrow); msg.push_str("!"); | Cannot mutate while borrowed. | Rust |
disp('hello') | disp('hello') | Correct. | MATLAB |
if (count = 92) {{}} | if (count === 92) {{}} | Use === for equality. | JavaScript |
def baz
puts 'world'
end | def baz
puts 'world'
end | Correct. | Ruby |
if (c = 2) | if (c == 2) | Use ==. | Scala |
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