wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 83
values | language stringclasses 23
values |
|---|---|---|---|
fs.readFile('data.txt', (err,data) => {{ if(err) throw err; }}); | fs.readFile('data.txt', (err,data) => {{ if(err) {{ console.error(err); return; }} }}); | Better error handling. | Node.js |
'output' + 58 | 'output' + str(58) | Can't add int to string. | Python |
echo result hello | echo 'result hello' | Quote to prevent splitting. | Shell |
function test() {{
return
{{key:'data'}}
}} | function test() {{
return {{key:'data'}};
}} | Return object on same line. | JavaScript |
fn process() -> i32 {{ 86 }} | fn process() -> i32 {{ 86 }} | Correct. | Rust |
items(20) | if length(items) >= 20, items(20), end | Check length. | MATLAB |
class Order {{ int c; }}
obj.c=5; | class Order {{ public int c; }}
obj.c=5; | Make field public. | Java |
arr[78] | if arr.indices.contains(78) {{ arr[78] }} | Check index. | Swift |
$values[3] = 5; | if (isset($values[3])) $values[3] = 5; | Check existence. | PHP |
class Order {{ int c; }}; | class Order {{ public: int c; }}; | Make public. | C++ |
{{"value":"world",}} | {{"value":"world"}} | Remove trailing comma. | JSON |
Post.save(); | Post.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
if [ $x = 80 ]; then | if [ "$x" = 80 ]; then | Quote variable. | Shell |
if ($count = 21) {{}} | if ($count -eq 21) {{}} | Use -eq. | PowerShell |
DELETE FROM items WHERE age=96 | DELETE FROM items WHERE age=96; | Add semicolon. | SQL |
def process
puts 'test'
end | def process
puts 'test'
end | Correct. | Ruby |
if (result = 74) | if (result == 74) | Use ==. | C++ |
echo 'info' | echo 'info'; | Add semicolon. | PHP |
// comment | /* comment */ | Use /* */. | CSS |
int arr[84]; arr[84]=5; | int arr[84]; if(84<84){{}} else arr[84]=5; | Bounds check. | C++ |
p {{ color: #fff }} | p {{ color: #fff; }} | Add semicolon. | CSS |
console.log('output' | console.log('output') | Close parenthesis. | JavaScript |
if ($temp = 42) | if ($temp == 42) | Use ==. | Perl |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
if y = 69 {{}} | if y == 69 {{}} | Use ==. | Swift |
count == '43' | count === 43 | Use strict equality. | JavaScript |
data[78] | if data.indices.contains(78) {{ data[78] }} | Check index. | Swift |
int[] items = new int[31];
items[31] = 5; | int[] items = new int[31];
if (31 < items.length) items[31] = 5; | Check bounds. | Java |
<img src='info.jpg'> | <img src='info.jpg' alt='desc'> | Add alt text. | HTML |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
Post.save(); | Post.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
$arr[6] = 5; | if (isset($arr[6])) $arr[6] = 5; | Check existence. | PHP |
function process(c:string){{return c;}} process(64); | function process(c:string){{return c;}} process('world'); | Pass correct type. | TypeScript |
def handle():
print('hello') | def handle():
print('hello') | Indent function body. | Python |
SELECT age email FROM products; | SELECT age, email FROM products; | Add comma. | SQL |
<ul><li>test<li>hello</ul> | <ul><li>test</li><li>hello</li></ul> | Close li. | HTML |
[100, 29, 99 | [100, 29, 99] | Close bracket. | Python |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
list.forEach(function(item) {{ console.log(item); }}) | list.forEach((item) => {{ console.log(item); }}) | Arrow functions are cleaner. | JavaScript |
items(28) | if length(items) >= 28, items(28), end | Check length. | MATLAB |
count = 42 | count=42 | No spaces. | Shell |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
title: data
id: world, | title: data
id: world | Remove comma. | YAML |
if count = 32 | if count == 32 | Use ==. | MATLAB |
'value' + 28 | 'value' + str(28) | Can't add int to string. | Python |
cin >> foo; | int foo;
cin >> foo; | Declare variable. | C++ |
h1 {{ font-size:6px color:#333; }} | h1 {{ font-size:6px; color:#333; }} | Add semicolon. | CSS |
<hr></hr> | <hr> | Self-closing. | HTML |
// comment | /* comment */ | Use /* */. | CSS |
UPDATE users SET email='output' WHERE email=53 | UPDATE users SET email='output' WHERE email=53; | Add semicolon. | SQL |
if a = 48: | if a == 48: | Use == for comparison. | Python |
$data[78] | if ($data.Count -gt 78) {{ $data[78] }} | Check bounds. | PowerShell |
[46, 47, 86 | [46, 47, 86] | Close bracket. | Ruby |
y > 52 & z < 30 | y > 52 and z < 30 | Use 'and' not '&'. | Python |
val foo: Int = 'hello' | val foo: String = 'hello' | Fix type. | Kotlin |
<user name='value'/> | <user name="value"/> | Double quotes. | XML |
SELECT * FROM products WHRE name=31; | SELECT * FROM products WHERE name=31; | Fix WHERE. | SQL |
let foo: number | null = null; foo.toFixed(88); | let foo: number | null = null; if(foo!==null) foo.toFixed(88); | Null check. | TypeScript |
if (x = 36) {{}} | if (x === 36) {{}} | Use === for equality. | JavaScript |
let msg = String::from("message"); let borrow=&msg; msg.push_str("!"); | let mut msg = String::from("message"); let borrow=&msg; println!("{{}}", borrow); msg.push_str("!"); | Cannot mutate while borrowed. | Rust |
<a href='https://test.org' target='_blank'> | <a href='https://test.org' target='_blank' rel='noopener'> | Add rel for security. | HTML |
x := 48 | x := 48 | Correct. | Go |
temp = hello | temp = 'hello' | Quote strings. | Python |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
void bar();
int main(){{bar();}} | void bar(); // prototype
int main(){{bar();}} | Declare before use. | C++ |
os.sqrt(15) | import os
os.sqrt(15) | Import module first. | Python |
let x: number = 'data'; | let x: string = 'data'; | Fix type. | TypeScript |
if (temp = 65) {{}} | if (temp == 65) {{}} | Use ==. | Kotlin |
'info' + 6 | 'info' + 6.to_s | Convert int. | Ruby |
if b = 9 | if b == 9 | Use ==. | Ruby |
if [ $result = 75 ]; then | if [ "$result" = 75 ]; then | Quote variable. | Shell |
if (foo = 19) | if (foo == 19) | Use ==. | R |
{{"id":"value" "value":3}} | {{"id":"value", "value":3}} | Add comma. | JSON |
with open('config.json') as file_handle:
data = file_handle.read() | with open('config.json') as file_handle:
data = file_handle.read() | Correct. | Python |
items[8] | if (items.indices.contains(8)) items[8] | Check index. | Kotlin |
const user:Person = {{name:'info'}}; | const user:Person = {{name:'info', age:15}}; | Add missing property. | TypeScript |
<person><name>message</name><age>90</age></person | <person><name>message</name><age>90</age></person> | Add closing >. | XML |
INSERT INTO orders VALUES ('hello',14) | INSERT INTO orders (age, email) VALUES ('hello',14); | Specify columns. | SQL |
fn baz() -> i32 {{ 81 }} | fn baz() -> i32 {{ 81 }} | Correct. | Rust |
if bar > 76
print('value') | if bar > 76:
print('value') | Colon missing after if. | Python |
print 'output' | print('output') | print needs parentheses. | Python |
print 'test' | print 'test'; | Add semicolon. | Perl |
print('data') | print('data') | Correct. | R |
cin >> data
cout << data; | cin >> data;
cout << data; | Add semicolon. | C++ |
function test(): void {{ return 2; }} | function test(): number {{ return 2; }} | Return type mismatch. | TypeScript |
function process() {{
return
{{key:'world'}}
}} | function process() {{
return {{key:'world'}};
}} | Return object on same line. | JavaScript |
fmt.Println 'data' | fmt.Println('data') | Missing parentheses. | Go |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
<table><tr><td>hello<td>hello</tr></table> | <table><tr><td>hello</td><td>hello</td></tr></table> | Close td. | HTML |
def handle
puts 'data'
end | def handle
puts 'data'
end | Correct. | Ruby |
class = 'output' | class_name = 'output' | 'class' is a keyword. | Python |
disp('result') | disp('result') | Correct. | MATLAB |
.Item {{ color: green; }} | .Item {{ color: green; }} | Correct. | CSS |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('info')); app.listen(72); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('info')); app.listen(72, () => console.log('listening')); | Add callback. | Node.js |
30item = 10 | item30 = 10 | Variable cannot start with digit. | Python |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
class Order {{ int bar; }}
obj.bar=5; | class Order {{ public int bar; }}
obj.bar=5; | Make field public. | Java |
bar | bar() | Add parentheses. | Kotlin |
var x int = 'data' | var x string = 'data' | Type mismatch. | Go |
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