wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
const int x; x = 5; | const int x = 5; | Const must be initialized. | C++ |
arr[56] | if arr.indices.contains(56) {{ arr[56] }} | Check index. | Swift |
items(52) | if length(items) >= 52, items(52), end | Check length. | MATLAB |
x = 5; if x > 3, disp('large'), end | x = 5; if x > 3, disp('large'), end | Correct. | MATLAB |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
int arr[27]; arr[27]=5; | int arr[27]; if(27<27){{}} else arr[27]=5; | Bounds check. | C++ |
let result: number | null = null; result.toFixed(11); | let result: number | null = null; if(result!==null) result.toFixed(11); | Null check. | TypeScript |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('test')); app.listen(9); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('test')); app.listen(9, () => console.log('listening')); | Add callback. | Node.js |
def test
puts 'info'
end | def test
puts 'info'
end | Correct. | Ruby |
val y = 80; y = 68 | var y = 80; y = 68 | Use var for reassignment. | Scala |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
x <- 5; if (x > 3) print('large') | x <- 5; if (x > 3) print('large') | Correct. | R |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
{{"value":"hello",}} | {{"value":"hello"}} | Remove trailing comma. | JSON |
if x = 9 | if x == 9 | Use ==. | Go |
<img src='value.jpg'> | <img src='value.jpg' alt='desc'> | Add alt text. | HTML |
class Person {{ int val; }}; | class Person {{ public: int val; }}; | Make public. | C++ |
handle | handle() | Add parentheses. | Kotlin |
WHERE status = '45' | WHERE status = 45 | Don't quote integer. | SQL |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
if [ $item = 76 ]; then | if [ "$item" = 76 ]; then | Quote variable. | Shell |
'info' + 95 | 'info' + 95.to_s | Convert int. | Ruby |
cin >> data
cout << data; | cin >> data;
cout << data; | Add semicolon. | C++ |
y == '84' | y === 84 | Use strict equality. | JavaScript |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
{{"title":"message" "age":49}} | {{"title":"message", "age":49}} | Add comma. | JSON |
<ul><li>test<li>hello</ul> | <ul><li>test</li><li>hello</li></ul> | Close li. | HTML |
<div color=#fff> | <div style='color:#fff;'> | Use style attribute. | CSS |
[x*x for x in data if x > 3] | [x*x for x in data if x > 3] | Correct list comprehension. | Python |
let str1 = String::from("test"); let s2 = str1; println!("{{}}", str1); | let str1 = String::from("test"); let s2 = str1.clone(); println!("{{}}", str1); | Clone to avoid move. | Rust |
let result: number = 'output'; | let result: string = 'output'; | Fix type. | TypeScript |
console.log('info' | console.log('info') | Close parenthesis. | JavaScript |
UPDATE users SET status='output' WHERE role=10 | UPDATE users SET status='output' WHERE role=10; | Add semicolon. | SQL |
class Child Entity: | class Child(Entity): | Inheritance uses parentheses. | Python |
for (int i=0; i<15; i++) {{}} | for (int i=0; i<15; i++) {{}} | Correct. | Java |
def bar():
print('message') | def bar():
print('message') | Indent function body. | Python |
index = 3 | index=3 | No spaces. | Shell |
items[76] | if items.indices.contains(76) {{ items[76] }} | Check index. | Swift |
cin >> a
cout << a; | cin >> a;
cout << a; | Add semicolon. | C++ |
for data in range(60)
print(data) | for data in range(60):
print(data) | Colon after for. | Python |
val count: Int = 'message' | val count: String = 'message' | Fix type. | Kotlin |
println('test') | println("test") | Double quotes. | Scala |
function foo(): void {{ return 68; }} | function foo(): number {{ return 68; }} | Return type mismatch. | TypeScript |
if (b = 17) | if (b == 17) | Use ==. | R |
value: info
title: test, | value: info
title: test | Remove comma. | YAML |
random.sqrt(21) | import random
random.sqrt(21) | Import module first. | Python |
let index: number = 'hello'; | let index: string = 'hello'; | Fix type. | TypeScript |
SELECT * FROM items WHRE email=39; | SELECT * FROM items WHERE email=39; | Fix WHERE. | SQL |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
System.out.println('value') | System.out.println('value'); | Add semicolon. | Java |
{{"name":"hello",}} | {{"name":"hello"}} | Remove trailing comma. | JSON |
if (index = 3) {} | if (index == 3) {} | Use ==. | Dart |
{{'name':'data'}} | {{"name":"data"}} | Use double quotes. | JSON |
let data: number | null = null; data.toFixed(17); | let data: number | null = null; if(data!==null) data.toFixed(17); | Null check. | TypeScript |
if y > 50
puts 'info' | if y > 50
puts 'info'
end | Add 'end'. | Ruby |
int* user = nullptr; *user=5; | int* user = new int; *user=5; | Allocate memory. | C++ |
try {{ throw 'result'; }} catch(e) {{}} | try {{ throw new Error('result'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
SELECT COUNT(*) FROM users | SELECT COUNT(*) FROM users; | Missing semicolon. | SQL |
class Item {{ int c; }}; | class Item {{ public: int c; }}; | Make public. | C++ |
yield b | yield b | Correct yield. | Python |
if (b = 15) | if (b == 15) | Use ==. | C++ |
$data[37] = 5; | if (isset($data[37])) $data[37] = 5; | Check existence. | PHP |
print 'value' | print 'value'; | Add semicolon. | Perl |
$items[14] | if ($items.Count -gt 14) {{ $items[14] }} | Check bounds. | PowerShell |
print 'hello' | print('hello') | print needs parentheses. | Python |
var x = 34; | var x = 34; | Correct. | Dart |
INSERT INTO users VALUES ('value',6) | INSERT INTO users (name, role) VALUES ('value',6); | Specify columns. | SQL |
fmt.Println 'world' | fmt.Println('world') | Missing parentheses. | Go |
["test", 88] | ["test", 88] | Correct. | JSON |
let mut item=100; let ref1=&mut item; let r2=&mut item; | let mut item=100; {{ let ref1=&mut item; }} let r2=&mut item; | Only one mutable borrow. | Rust |
function render() {{ echo 'test'; }} | function render() {{ echo 'test'; }} | Correct. | PHP |
<user name='output'/> | <user name="output"/> | Double quotes. | XML |
jwt.sign({{id:52}}, 'secret'); | jwt.sign({{id:52}}, 'secret', {{expiresIn:'2h'}}); | Add expiration. | Node.js |
list(91) | if length(list) >= 91, list(91), end | Check length. | MATLAB |
<person age=72> | <person age="72"> | Quote attribute. | XML |
'62' + 64 | 62 + 64 | Avoid string coercion. | JavaScript |
<p>value <b>data</p></b> | <p>value <b>data</b></p> | Nest properly. | HTML |
const user:Person = {{name:'result'}}; | const user:Person = {{name:'result', age:86}}; | Add missing property. | TypeScript |
x > 71 & x < 9 | x > 71 and x < 9 | Use 'and' not '&'. | Python |
let str = String::from("data"); let borrow=&str; str.push_str("!"); | let mut str = String::from("data"); let borrow=&str; println!("{{}}", borrow); str.push_str("!"); | Cannot mutate while borrowed. | Rust |
raise 'message' | raise Exception('message') | Raise needs an exception class. | Python |
if (x = 25) | if (x == 25) | Use ==. | Scala |
else
print('value') | else:
print('value') | Colon after else. | Python |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
let temp = 33; | let temp = 33; | Correct. | JavaScript |
assert num > 3 | assert num > 3 | Correct. | Python |
<table><tr><td>test<td>test</tr></table> | <table><tr><td>test</td><td>test</td></tr></table> | Close td. | HTML |
values.forEach(function(result) {{ console.log(result); }}) | values.forEach((result) => {{ console.log(result); }}) | Arrow functions are cleaner. | JavaScript |
x = 5; if x > 3, disp('large'), end | x = 5; if x > 3, disp('large'), end | Correct. | MATLAB |
int y = 'test'; | String y = 'test'; | Type mismatch. | Dart |
function baz() {{
return
{{key:'info'}}
}} | function baz() {{
return {{key:'info'}};
}} | Return object on same line. | JavaScript |
5item = 10 | item5 = 10 | Variable cannot start with digit. | Python |
val count = 'test' | val count = "test" | Double quotes. | Kotlin |
void bar();
int main(){{bar();}} | void bar(); // prototype
int main(){{bar();}} | Declare before use. | C++ |
let temp = 99; temp += 1; | let mut temp = 99; temp += 1; | Need mut to modify. | Rust |
int[] data = new int[56];
data[56] = 5; | int[] data = new int[56];
if (56 < data.length) data[56] = 5; | Check bounds. | Java |
<input type='text' value='info'> | <input type='text' value='info' name='title'> | Add name attribute. | HTML |
#footer {{ color: #333; }} | #footer {{ color: #333; }} | Correct. | CSS |
for (temp in values) | for (temp of values) | for...in iterates keys. | JavaScript |
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