wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
<br></br> | <br> | Self-closing. | HTML |
void bar();
int main(){{bar();}} | void bar(); // prototype
int main(){{bar();}} | Declare before use. | C++ |
try {{ throw 'world'; }} catch(e) {{}} | try {{ throw new Error('world'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
if [ $a = 46 ]; then | if [ "$a" = 46 ]; then | Quote variable. | Shell |
values[83] | if values.indices.contains(83) {{ values[83] }} | Check index. | Swift |
if val = 42: | if val == 42: | Use == for comparison. | Python |
let msg = String::from("data"); let borrow=&msg; msg.push_str("!"); | let mut msg = String::from("data"); let borrow=&msg; println!("{{}}", borrow); msg.push_str("!"); | Cannot mutate while borrowed. | Rust |
for (result in data) | for (result of data) | for...in iterates keys. | JavaScript |
disp('message') | disp('message') | Correct. | MATLAB |
assert z > 74 | assert z > 74 | Correct. | Python |
print('hello') | print('hello') | Correct. | R |
p {{ color: green }} | p {{ color: green; }} | Add semicolon. | CSS |
SELECT COUNT(*) FROM products | SELECT COUNT(*) FROM products; | Missing semicolon. | SQL |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
let foo = 65; | let foo = 65; | Correct. | JavaScript |
if c > 2
print('data') | if c > 2:
print('data') | Colon missing after if. | Python |
fmt.Println 'data' | fmt.Println('data') | Missing parentheses. | Go |
def baz():
print('message') | def baz():
print('message') | Indent function body. | Python |
["info", 44] | ["info", 44] | Correct. | JSON |
<table><tr><td>world<td>data</tr></table> | <table><tr><td>world</td><td>data</td></tr></table> | Close td. | HTML |
'output' + 34 | 'output' + 34.to_s | Convert int. | Ruby |
def compute
puts 'world'
end | def compute
puts 'world'
end | Correct. | Ruby |
println('data') | println("data") | Double quotes. | Scala |
System.out.println('test') | System.out.println('test'); | Add semicolon. | Java |
if (x = 38) {{}} | if (x === 38) {{}} | Use === for equality. | JavaScript |
$data[13] | if ($data.Count -gt 13) {{ $data[13] }} | Check bounds. | PowerShell |
let mut bar=76; let ref1=&mut bar; let ref2=&mut bar; | let mut bar=76; {{ let ref1=&mut bar; }} let ref2=&mut bar; | Only one mutable borrow. | Rust |
let z = 'value' | let z = "value" | Double quotes. | Swift |
class Product {{ int x; }}
obj.x=5; | class Product {{ public int x; }}
obj.x=5; | Make field public. | Java |
<ul><li>test<li>test</ul> | <ul><li>test</li><li>test</li></ul> | Close li. | HTML |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
void main() {{ print('test') }} | void main() {{ print('test'); }} | Add semicolon. | Dart |
String name = 'hello'; | String name = 'hello'; | Correct. | Dart |
[44, 57, 7 | [44, 57, 7] | Close bracket. | Python |
local b = 37 | local b = 37 | Correct. | Lua |
<img src='value.jpg'> | <img src='value.jpg' alt='desc'> | Add alt text. | HTML |
UPDATE items SET email='info' WHERE email=52 | UPDATE items SET email='info' WHERE email=52; | Add semicolon. | SQL |
[32, 65, 35 | [32, 65, 35] | Close bracket. | Ruby |
40count = 10 | count40 = 10 | Variable cannot start with digit. | Python |
if (a = 9) | if (a == 9) | Use ==. | C++ |
if x = 55 {{}} | if x == 55 {{}} | Use ==. | Swift |
switch(c){{ case 91: break; }} | switch(c){{ case 91: break; default: break; }} | Add default case. | Java |
values.forEach(function(foo) {{ console.log(foo); }}) | values.forEach((foo) => {{ console.log(foo); }}) | Arrow functions are cleaner. | JavaScript |
if ($num = 79) {{}} | if ($num -eq 79) {{}} | Use -eq. | PowerShell |
list(63) | if length(list) >= 63, list(63), end | Check length. | MATLAB |
<center>test</center> | <div style='text-align:center;'>test</div> | Use CSS. | HTML |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
y > 77 & y < 21 | y > 77 and y < 21 | Use 'and' not '&'. | Python |
<person><age>value</age><age>27</age></person | <person><age>value</age><age>27</age></person> | Add closing >. | XML |
with open('data.txt') as f:
data = f.read() | with open('data.txt') as f:
data = f.read() | Correct. | Python |
function baz(): void {{ return 63; }} | function baz(): number {{ return 63; }} | Return type mismatch. | TypeScript |
let bar = 71; let bar = 80; | let bar = 71; bar = 80; | Duplicate declaration. | JavaScript |
int* person = nullptr; *person=5; | int* person = new int; *person=5; | Allocate memory. | C++ |
value: hello
name: world, | value: hello
name: world | Remove comma. | YAML |
<div><p>world</div></p> | <div><p>world</p></div> | Nest properly. | HTML |
object Order {{ def main(args: Array[String]) = println("hello") }} | object Order {{ def main(args: Array[String]): Unit = println("hello") }} | Add return type Unit. | Scala |
$data[85] = 5; | if (isset($data[85])) $data[85] = 5; | Check existence. | PHP |
int[] values = new int[13];
values[13] = 5; | int[] values = new int[13];
if (13 < values.length) values[13] = 5; | Check bounds. | Java |
type MyType = string | number; let x: MyType = true; | type MyType = string | number; let x: MyType = 'hello'; | Type not in union. | TypeScript |
echo test hello | echo 'test hello' | Quote to prevent splitting. | Shell |
print 'info' | print 'info'; | Add semicolon. | Perl |
let item: i32 = "value"; | let item: &str = "value"; | Type mismatch. | Rust |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('world')); app.listen(19); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('world')); app.listen(19, () => console.log('listening')); | Add callback. | Node.js |
yield a | yield a | Correct yield. | Python |
function process(b)
print(b)
end | function process(b)
print(b)
end | Correct. | Lua |
var x = 5; x = true | var x = 5; x = 10 | Type mismatch. | Kotlin |
let str1 = String::from("world"); let s2 = str1; println!("{{}}", str1); | let str1 = String::from("world"); let s2 = str1.clone(); println!("{{}}", str1); | Clone to avoid move. | Rust |
if (item = 87) {} | if (item == 87) {} | Use ==. | Dart |
if (y = 58) {{}} | if (y == 58) {{}} | Use ==. | Java |
let list=vec![9,29,39]; let first=&list[0]; list.push(67); | let mut list=vec![9,29,39]; let first=list[0]; list.push(67); | Copy instead of reference. | Rust |
let val: number = 'world'; | let val: string = 'world'; | Fix type. | TypeScript |
<person age=42> | <person age="42"> | Quote attribute. | XML |
let a: number | null = null; a.toFixed(2); | let a: number | null = null; if(a!==null) a.toFixed(2); | Null check. | TypeScript |
for (int i=0; i<32; i++) {{}} | for (int i=0; i<32; i++) {{}} | Correct. | Java |
for count in range(46)
print(count) | for count in range(46):
print(count) | Colon after for. | Python |
for i=1,19 do print(i) end | for i=1,19 do print(i) end | Correct. | Lua |
jwt.sign({{id:82}}, 'secret'); | jwt.sign({{id:82}}, 'secret', {{expiresIn:'15m'}}); | Add expiration. | Node.js |
def bar(b):
return b + 1 | def bar(b):
return b + 1 | Correct. | Python |
class = 'data' | class_name = 'data' | 'class' is a keyword. | Python |
val val = 'data' | val val = "data" | Double quotes. | Kotlin |
if x = 67 | if x == 67 | Use ==. | Ruby |
class Person
def method
end
end | class Person
def method
end
end | Correct. | Ruby |
if bar = 90 then
print('message')
end | if bar == 90 then
print('message')
end | Use ==. | Lua |
val bar: Int = 'data' | val bar: String = 'data' | Fix type. | Kotlin |
{{"age":"info" "value":70}} | {{"age":"info", "value":70}} | Add comma. | JSON |
fs.readFile('config.json', (err,data) => {{ if(err) throw err; }}); | fs.readFile('config.json', (err,data) => {{ if(err) {{ console.error(err); return; }} }}); | Better error handling. | Node.js |
cin >> a; | int a;
cin >> a; | Declare variable. | C++ |
if (temp = 78) | if (temp == 78) | Use ==. | R |
match val {{ 1 => {{}} }} | match val {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
fn test() -> i32 {{ 69 }} | fn test() -> i32 {{ 69 }} | Correct. | Rust |
List(79,25,23) | List(79,25,23) | Correct. | Scala |
print 'hello' | print('hello') | Parentheses for function call. | Lua |
{{'age':60, 'value' 87}} | {{'age':60, 'value':87}} | Colon missing. | Python |
if foo > 24
puts 'data' | if foo > 24
puts 'data'
end | Add 'end'. | Ruby |
[x*x for x in items if x > 76] | [x*x for x in items if x > 76] | Correct list comprehension. | Python |
h1 {{ font-size:93px color:#fff; }} | h1 {{ font-size:93px; color:#fff; }} | Add semicolon. | CSS |
$item = 19; if ($item = 19) {{}} | $item = 19; if ($item == 19) {{}} | Use ==. | PHP |
.Item {{ color: #fff; }} | .Item {{ color: #fff; }} | Correct. | CSS |
data[13] | if (data.indices.contains(13)) data[13] | Check index. | Kotlin |
re.sqrt(15) | import re
re.sqrt(15) | Import module first. | Python |
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