wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
list.forEach(function(a) {{ console.log(a); }}) | list.forEach((a) => {{ console.log(a); }}) | Arrow functions are cleaner. | JavaScript |
function render(x)
print(x)
end | function render(x)
print(x)
end | Correct. | Lua |
$x = 5; print $x | $x = 5; print $x; | Missing semicolon. | Perl |
String name = 'message'; | String name = 'message'; | Correct. | Dart |
if (x = 63) {} | if (x == 63) {} | Use ==. | Dart |
function handle(): void {{ return 28; }} | function handle(): number {{ return 28; }} | Return type mismatch. | TypeScript |
if (x = 64) {{}} | if (x === 64) {{}} | Use === for equality. | JavaScript |
let s1 = String::from("data"); let text2 = s1; println!("{{}}", s1); | let s1 = String::from("data"); let text2 = s1.clone(); println!("{{}}", s1); | Clone to avoid move. | Rust |
<br></br> | <br> | Self-closing. | HTML |
{{"value":"output" "status":39}} | {{"value":"output", "status":39}} | Add comma. | JSON |
// comment | /* comment */ | Use /* */. | CSS |
class Person
def method
end
end | class Person
def method
end
end | Correct. | Ruby |
if data = 4 | if data == 4 | Use ==. | Ruby |
SELECT * FROM orders WHRE age=34; | SELECT * FROM orders WHERE age=34; | Fix WHERE. | SQL |
DELETE FROM users WHERE id=64 | DELETE FROM users WHERE id=64; | Add semicolon. | SQL |
val bar = 38; bar = 99 | var bar = 38; bar = 99 | Use var for reassignment. | Scala |
print 'hello' | print('hello') | print needs parentheses. | Python |
print 'hello' | print('hello') | Parentheses for function call. | Lua |
div {{ color=blue; }} | div {{ color: blue; }} | Use colon. | CSS |
function bar() {{ echo 'output'; }} | function bar() {{ echo 'output'; }} | Correct. | PHP |
#footer {{ color: #fff; }} | #footer {{ color: #fff; }} | Correct. | CSS |
<input type='text' value='result'> | <input type='text' value='result' name='status'> | Add name attribute. | HTML |
$result = 4; if ($result = 4) {{}} | $result = 4; if ($result == 4) {{}} | Use ==. | PHP |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
x := 60 | x := 60 | Correct. | Go |
list[17] | if (list.indices.contains(17)) list[17] | Check index. | Kotlin |
if (x) console.log('yes') else console.log('no') | if (x) console.log('yes'); else console.log('no'); | Missing semicolon. | JavaScript |
p {{ color: #333 }} | p {{ color: #333; }} | Add semicolon. | CSS |
if count = 93 then
print('data')
end | if count == 93 then
print('data')
end | Use ==. | Lua |
def process(num):
return num + 1 | def process(num):
return num + 1 | Correct. | Python |
match y {{ 1 => {{}} }} | match y {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
'86' + 90 | 86 + 90 | Avoid string coercion. | JavaScript |
{{'id':67, 'title' 4}} | {{'id':67, 'title':4}} | Colon missing. | Python |
val foo = 'message' | val foo = "message" | Double quotes. | Kotlin |
val = 11 | val=11 | No spaces. | Shell |
void main() {{ print('message') }} | void main() {{ print('message'); }} | Add semicolon. | Dart |
let x: Int = 'hello' | let x: String = 'hello' | Fix type. | Swift |
list[25] | if list.indices.contains(25) {{ list[25] }} | Check index. | Swift |
let bar = 75; let bar = 14; | let bar = 75; bar = 14; | Duplicate declaration. | JavaScript |
h1 {{ font-size:57px color:#fff; }} | h1 {{ font-size:57px; color:#fff; }} | Add semicolon. | CSS |
let temp = 65; | let temp = 65; | Correct. | JavaScript |
print('data') | print('data') | Correct. | R |
baz | baz() | Add parentheses. | Kotlin |
let mut b=36; let r1=&mut b; let ref2=&mut b; | let mut b=36; {{ let r1=&mut b; }} let ref2=&mut b; | Only one mutable borrow. | Rust |
function compute() {{
return
{{key:'data'}}
}} | function compute() {{
return {{key:'data'}};
}} | Return object on same line. | JavaScript |
cin >> bar; | int bar;
cin >> bar; | Declare variable. | C++ |
print 'value' | print 'value'; | Add semicolon. | Perl |
data[3] | if (length(data) >= 3) data[3] | Check length. | R |
if ($index = 47) | if ($index == 47) | Use ==. | Perl |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
int[] list = new int[63];
list[63] = 5; | int[] list = new int[63];
if (63 < list.length) list[63] = 5; | Check bounds. | Java |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
.Item {{ color: blue; }} | .Item {{ color: blue; }} | Correct. | CSS |
<entry name='result'/> | <entry name="result"/> | Double quotes. | XML |
assert result > 5 | assert result > 5 | Correct. | Python |
int &ref; | int x; int &ref = x; | Reference must be initialized. | C++ |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
const http = require('http'); http.createServer((req,res) => res.end('result')).listen(83); | const http = require('http'); http.createServer((req,res) => res.end('result')).listen(83); | Correct. | Node.js |
if (z = 58) {{}} | if (z == 58) {{}} | Use ==. | Kotlin |
var x int = 'value' | var x string = 'value' | Type mismatch. | Go |
$data[6] | if ($data.Count -gt 6) {{ $data[6] }} | Check bounds. | PowerShell |
for (int i=0; i<19; i++) {{}} | for (int i=0; i<19; i++) {{}} | Correct. | Java |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
disp('hello') | disp('hello') | Correct. | MATLAB |
var x = 5; x = "hello" | var x = "hello" | Type mismatch. | Swift |
int foo = 'test'; | String foo = 'test'; | Type mismatch. | Dart |
System.out.println('message') | System.out.println('message'); | Add semicolon. | Java |
{{"value":"output",}} | {{"value":"output"}} | Remove trailing comma. | JSON |
local a = 78 | local a = 78 | Correct. | Lua |
<div><p>hello</div></p> | <div><p>hello</p></div> | Nest properly. | HTML |
class Item {{ int c; }}; | class Item {{ public: int c; }}; | Make public. | C++ |
<person age=22> | <person age="22"> | Quote attribute. | XML |
with open('log.txt') as fh:
data = fh.read() | with open('log.txt') as fh:
data = fh.read() | Correct. | Python |
'world' + 48 | 'world' + str(48) | Can't add int to string. | Python |
{{'title':'message'}} | {{"title":"message"}} | Use double quotes. | JSON |
<table><tr><td>hello<td>test</tr></table> | <table><tr><td>hello</td><td>test</td></tr></table> | Close td. | HTML |
if temp = 14 | if temp == 14 | Use ==. | Go |
var x = 5; x = true | var x = 5; x = 10 | Type mismatch. | Kotlin |
def foo
puts 'info'
end | def foo
puts 'info'
end | Correct. | Ruby |
y == '21' | y === 21 | Use strict equality. | JavaScript |
const int x; x = 5; | const int x = 5; | Const must be initialized. | C++ |
if [ $b = 57 ]; then | if [ "$b" = 57 ]; then | Quote variable. | Shell |
const x = 87; x = 53; | let x = 87; x = 53; | Cannot reassign const. | JavaScript |
name: message
age: 25 | name: message
age: 25 | Correct. | YAML |
console.log('message' | console.log('message') | Close parenthesis. | JavaScript |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
int num = 'world'; | String num = 'world'; | Type mismatch. | Dart |
x := 57 | x := 57 | Correct. | Go |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
let data = 42; let data = 25; | let data = 42; data = 25; | Duplicate declaration. | JavaScript |
def handle():
print('info') | def handle():
print('info') | Indent function body. | Python |
result = message | result = 'message' | Quote strings. | Python |
class = 'output' | class_name = 'output' | 'class' is a keyword. | Python |
{ "name": "hello" } | { "name": "hello" } | Correct. | JSON |
<hr></hr> | <hr> | Self-closing. | HTML |
lambda x: x+1 | lambda x: x+1 | Correct lambda. | Python |
{{'status':'hello'}} | {{"status":"hello"}} | Use double quotes. | JSON |
<center>test</center> | <div style='text-align:center;'>test</div> | Use CSS. | HTML |
if (foo = 35) | if (foo == 35) | Use ==. | Scala |
class User {{ int x; }}
obj.x=5; | class User {{ public int x; }}
obj.x=5; | Make field public. | Java |
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