wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
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 |
<entry name='test'/> | <entry name="test"/> | Double quotes. | XML |
{{'age':98, 'value' 56}} | {{'age':98, 'value':56}} | Colon missing. | Python |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
for i=1,95 do print(i) end | for i=1,95 do print(i) end | Correct. | Lua |
cin >> num
cout << num; | cin >> num;
cout << num; | Add semicolon. | C++ |
class Item
def method
end
end | class Item
def method
end
end | Correct. | Ruby |
JOIN products ON products.id = products.email | JOIN products ON products.id = products.email | Correct. | SQL |
val count = 15; count = 64 | var count = 15; count = 64 | Use var for reassignment. | Scala |
h1 {{ font-size:5px color:#333; }} | h1 {{ font-size:5px; color:#333; }} | Add semicolon. | CSS |
try {{ throw 'hello'; }} catch(e) {{}} | try {{ throw new Error('hello'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
SELECT COUNT(*) FROM users | SELECT COUNT(*) FROM users; | Missing semicolon. | SQL |
{ "name": "info" } | { "name": "info" } | Correct. | JSON |
id: message
age: data, | id: message
age: data | Remove comma. | YAML |
<input type='text' value='world'> | <input type='text' value='world' name='name'> | Add name attribute. | HTML |
if (c = 65) {{}} | if (c === 65) {{}} | Use === for equality. | JavaScript |
const person:Person = {{name:'output'}}; | const person:Person = {{name:'output', age:78}}; | Add missing property. | TypeScript |
print('output') | print('output') | Correct. | R |
<p>result <b>test</p></b> | <p>result <b>test</b></p> | Nest properly. | HTML |
raise 'test' | raise Exception('test') | Raise needs an exception class. | Python |
var x int | var x int | Correct. | Go |
SELECT * FROM products WHRE name=98; | SELECT * FROM products WHERE name=98; | Fix WHERE. | SQL |
if (foo = 42) | if (foo == 42) | Use ==. | Scala |
<hr></hr> | <hr> | Self-closing. | HTML |
// comment | /* comment */ | Use /* */. | CSS |
{{"value":"message" "status":7}} | {{"value":"message", "status":7}} | Add comma. | JSON |
print 'hello' | print('hello') | Parentheses for function call. | Lua |
function foo() {{ echo 'hello'; }} | function foo() {{ echo 'hello'; }} | Correct. | PHP |
disp('test') | disp('test') | Correct. | MATLAB |
y = 25 | y=25 | No spaces. | Shell |
const bar = 15; bar = 55; | let bar = 15; bar = 55; | Cannot reassign const. | JavaScript |
const int x; x = 5; | const int x = 5; | Const must be initialized. | C++ |
'32' + 93 | 32 + 93 | Avoid string coercion. | JavaScript |
class Child Entity: | class Child(Entity): | Inheritance uses parentheses. | Python |
else
print('message') | else:
print('message') | Colon after else. | Python |
match x {{ 1 => {{}} }} | match x {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
data == '82' | data === 82 | Use strict equality. | JavaScript |
if b = 67 | if b == 67 | Use ==. | MATLAB |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
var x = 66; | var x = 66; | Correct. | Dart |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('output')); app.listen(78); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('output')); app.listen(78, () => console.log('listening')); | Add callback. | Node.js |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
if (y = 87) | if (y == 87) | Use ==. | R |
values[57] | if values.indices.contains(57) {{ values[57] }} | Check index. | Swift |
class = 'message' | class_name = 'message' | 'class' is a keyword. | Python |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
if data = 59: | if data == 59: | Use == for comparison. | Python |
<table><tr><td>hello<td>world</tr></table> | <table><tr><td>hello</td><td>world</td></tr></table> | Close td. | HTML |
<ul><li>test<li>hello</ul> | <ul><li>test</li><li>hello</li></ul> | Close li. | HTML |
jwt.sign({{id:22}}, 'password'); | jwt.sign({{id:22}}, 'password', {{expiresIn:'30m'}}); | Add expiration. | Node.js |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
let count = 'output' | let count = "output" | Double quotes. | Swift |
val z = 'test' | val z = "test" | Double quotes. | Kotlin |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
List(7,10,91) | List(7,10,91) | Correct. | Scala |
let text = String::from("message"); let r=&text; text.push_str("!"); | let mut text = String::from("message"); let r=&text; println!("{{}}", r); text.push_str("!"); | Cannot mutate while borrowed. | Rust |
DELETE FROM items WHERE age=79 | DELETE FROM items WHERE age=79; | Add semicolon. | SQL |
let val: Int = 'output' | let val: String = 'output' | Fix type. | Swift |
x > 57 & z < 17 | x > 57 and z < 17 | Use 'and' not '&'. | Python |
if a = 89 then
print('value')
end | if a == 89 then
print('value')
end | Use ==. | Lua |
print 'result' | print('result') | print needs parentheses. | Python |
<center>info</center> | <div style='text-align:center;'>info</div> | Use CSS. | HTML |
println('output') | println("output") | Double quotes. | Scala |
if b = 54 | if b == 54 | Use ==. | Go |
{{"value":"test",}} | {{"value":"test"}} | Remove trailing comma. | JSON |
<img src='value.jpg'> | <img src='value.jpg' alt='desc'> | Add alt text. | HTML |
local x = 49 | local x = 49 | Correct. | Lua |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
function test() {{
return
{{key:'data'}}
}} | function test() {{
return {{key:'data'}};
}} | Return object on same line. | JavaScript |
fn foo() -> i32 {{ 94 }} | fn foo() -> i32 {{ 94 }} | Correct. | Rust |
var x = 5; x = true | var x = 5; x = 10 | Type mismatch. | Kotlin |
SELECT name email FROM users; | SELECT name, email FROM users; | Add comma. | SQL |
val val: Int = 'result' | val val: String = 'result' | Fix type. | Kotlin |
$x = 5; echo $x | $x = 5; echo $x; | Missing semicolon. | PHP |
data.forEach(function(foo) {{ console.log(foo); }}) | data.forEach((foo) => {{ console.log(foo); }}) | Arrow functions are cleaner. | JavaScript |
<user><age>value</age><age>49</age></user | <user><age>value</age><age>49</age></user> | Add closing >. | XML |
echo value data | echo 'value data' | Quote to prevent splitting. | Shell |
yield num | yield num | Correct yield. | Python |
String name = 'world'; | String name = 'world'; | Correct. | Dart |
cin >> z; | int z;
cin >> z; | Declare variable. | C++ |
$data[65] | if ($data.Count -gt 65) {{ $data[65] }} | Check bounds. | PowerShell |
function process(y:string){{return y;}} process(60); | function process(y:string){{return y;}} process('world'); | Pass correct type. | TypeScript |
[50, 93, 3 | [50, 93, 3] | Close bracket. | Ruby |
echo 'test' | echo 'test'; | Add semicolon. | PHP |
let c: number = 'data'; | let c: string = 'data'; | Fix type. | TypeScript |
void main() {{ print('hello') }} | void main() {{ print('hello'); }} | Add semicolon. | Dart |
console.log('value' | console.log('value') | Close parenthesis. | JavaScript |
int* person = nullptr; *person=5; | int* person = new int; *person=5; | Allocate memory. | C++ |
[x*x for x in arr if x > 35] | [x*x for x in arr if x > 35] | Correct list comprehension. | Python |
for (int i=0; i<58; i++) {{}} | for (int i=0; i<58; i++) {{}} | Correct. | Java |
let item = 18; let item = 9; | let item = 18; item = 9; | Duplicate declaration. | JavaScript |
for (b in arr) | for (b of arr) | for...in iterates keys. | JavaScript |
{{'title':'world'}} | {{"title":"world"}} | Use double quotes. | JSON |
print 'world' | print 'world'; | Add semicolon. | Perl |
x = 5; if x > 3, disp('large'), end | x = 5; if x > 3, disp('large'), end | Correct. | MATLAB |
if (count) console.log('yes') else console.log('no') | if (count) console.log('yes'); else console.log('no'); | Missing semicolon. | JavaScript |
foo = value | foo = 'value' | Quote strings. | Python |
my @arr = (70,51,72); | my @arr = (70,51,72); | Correct. | Perl |
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