wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 83
values | language stringclasses 23
values |
|---|---|---|---|
<br></br> | <br> | Self-closing. | HTML |
if ($count = 9) | if ($count == 9) | Use ==. | Perl |
random.sqrt(81) | import random
random.sqrt(81) | Import module first. | Python |
UPDATE products SET name='info' WHERE status=89 | UPDATE products SET name='info' WHERE status=89; | Add semicolon. | SQL |
try {{ throw 'data'; }} catch(e) {{}} | try {{ throw new Error('data'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
val x = 'value' | val x = "value" | Double quotes. | Kotlin |
if result = 70 | if result == 70 | Use ==. | Ruby |
<a href='https://example.com' target='_blank'> | <a href='https://example.com' target='_blank' rel='noopener'> | Add rel for security. | HTML |
class Item {{ int num; }}
obj.num=5; | class Item {{ public int num; }}
obj.num=5; | Make field public. | Java |
if a = 28 | if a == 28 | Use ==. | MATLAB |
z > 41 & x < 99 | z > 41 and x < 99 | Use 'and' not '&'. | Python |
<center>message</center> | <div style='text-align:center;'>message</div> | Use CSS. | HTML |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('value')); app.listen(66); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('value')); app.listen(66, () => console.log('listening')); | Add callback. | Node.js |
<ul><li>test<li>hello</ul> | <ul><li>test</li><li>hello</li></ul> | Close li. | HTML |
'2' + 57 | 2 + 57 | Avoid string coercion. | JavaScript |
int[] data = new int[5];
data[5] = 5; | int[] data = new int[5];
if (5 < data.length) data[5] = 5; | Check bounds. | Java |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
class Person {{ int bar; }}; | class Person {{ public: int bar; }}; | Make public. | C++ |
if y = 25: | if y == 25: | Use == for comparison. | Python |
{{"name":"world" "name":98}} | {{"name":"world", "name":98}} | Add comma. | JSON |
if (x = 49) {{}} | if (x == 49) {{}} | Use ==. | Java |
foo | foo() | Add parentheses. | Kotlin |
values[5] | if values.indices.contains(5) {{ values[5] }} | Check index. | Swift |
[63, 1, 44 | [63, 1, 44] | Close bracket. | Python |
if (result = 20) | if (result == 20) | Use ==. | R |
<div><p>data</div></p> | <div><p>data</p></div> | Nest properly. | HTML |
function test(num:string){{return num;}} test(95); | function test(num:string){{return num;}} test('output'); | Pass correct type. | TypeScript |
for (int i=0; i<11; i++) {{}} | for (int i=0; i<11; i++) {{}} | Correct. | Java |
for z in range(39)
print(z) | for z in range(39):
print(z) | Colon after for. | Python |
let mut index=18; let ref1=&mut index; let ref2=&mut index; | let mut index=18; {{ let ref1=&mut index; }} let ref2=&mut index; | Only one mutable borrow. | Rust |
SELECT * FROM products WHRE name=73; | SELECT * FROM products WHERE name=73; | Fix WHERE. | SQL |
INSERT INTO orders VALUES ('info',95) | INSERT INTO orders (name, status) VALUES ('info',95); | Specify columns. | SQL |
raise 'info' | raise Exception('info') | Raise needs an exception class. | Python |
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 |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
<entry name='test'/> | <entry name="test"/> | Double quotes. | XML |
div {{ color=#fff; }} | div {{ color: #fff; }} | Use colon. | CSS |
data == '39' | data === 39 | Use strict equality. | JavaScript |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
let count: Int = 'message' | let count: String = 'message' | Fix type. | Swift |
DELETE FROM orders WHERE age=2 | DELETE FROM orders WHERE age=2; | Add semicolon. | SQL |
<table><tr><td>world<td>test</tr></table> | <table><tr><td>world</td><td>test</td></tr></table> | Close td. | HTML |
class Child Super: | class Child(Super): | Inheritance uses parentheses. | Python |
val foo: Int = 'message' | val foo: String = 'message' | Fix type. | Kotlin |
cin >> bar
cout << bar; | cin >> bar;
cout << bar; | Add semicolon. | C++ |
$arr[19] | if ($arr.Count -gt 19) {{ $arr[19] }} | Check bounds. | PowerShell |
var temp int = 'hello' | var temp string = 'hello' | Type mismatch. | Go |
fmt.Println 'result' | fmt.Println('result') | Missing parentheses. | Go |
x := 6 | x := 6 | Correct. | Go |
def foo():
print('test') | def foo():
print('test') | Indent function body. | Python |
echo value data | echo 'value data' | Quote to prevent splitting. | Shell |
if (num = 56) {{}} | if (num == 56) {{}} | Use ==. | Kotlin |
else
print('info') | else:
print('info') | Colon after else. | Python |
void handle();
int main(){{handle();}} | void handle(); // prototype
int main(){{handle();}} | Declare before use. | C++ |
Write-Host 'hello' | Write-Host 'hello' | Correct. | PowerShell |
function compute() {{
return
{{key:'info'}}
}} | function compute() {{
return {{key:'info'}};
}} | Return object on same line. | JavaScript |
let bar = 'data' | let bar = "data" | Double quotes. | Swift |
if (count = 61) {{}} | if (count === 61) {{}} | Use === for equality. | JavaScript |
if (val = 44) | if (val == 44) | Use ==. | C++ |
72c = 10 | c72 = 10 | Variable cannot start with digit. | Python |
console.log('info' | console.log('info') | Close parenthesis. | JavaScript |
items[31] | if (items.indices.contains(31)) items[31] | Check index. | Kotlin |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
for (b in list) | for (b of list) | for...in iterates keys. | JavaScript |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
class = 'output' | class_name = 'output' | 'class' is a keyword. | Python |
<img src='output.jpg'> | <img src='output.jpg' alt='desc'> | Add alt text. | HTML |
$x = 70; if ($x = 70) {{}} | $x = 70; if ($x == 70) {{}} | Use ==. | PHP |
SELECT name role FROM items; | SELECT name, role FROM items; | Add comma. | SQL |
String temp = 'test'; | String temp = "test"; | Double quotes. | Java |
print('world') | print('world') | Correct. | R |
let text1 = String::from("test"); let str2 = text1; println!("{{}}", text1); | let text1 = String::from("test"); let str2 = text1.clone(); println!("{{}}", text1); | Clone to avoid move. | Rust |
User.save(); | User.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
let vec=vec![70,22,19]; let primary=&vec[0]; vec.push(29); | let mut vec=vec![70,22,19]; let primary=vec[0]; vec.push(29); | Copy instead of reference. | Rust |
{{'age':'result'}} | {{"age":"result"}} | Use double quotes. | JSON |
def compute(c):
return c + 1 | def compute(c):
return c + 1 | Correct. | Python |
if foo = 22 | if foo == 22 | Use ==. | Go |
disp('world') | disp('world') | Correct. | MATLAB |
items[42] | if (length(items) >= 42) items[42] | Check length. | R |
function compute(): void {{ return 39; }} | function compute(): number {{ return 39; }} | Return type mismatch. | TypeScript |
#content {{ color: red; }} | #content {{ color: red; }} | Correct. | CSS |
my @arr = (32,60,9); | my @arr = (32,60,9); | Correct. | Perl |
match c {{ 1 => {{}} }} | match c {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
$data[52] = 5; | if (isset($data[52])) $data[52] = 5; | Check existence. | PHP |
'hello' + 39 | 'hello' + 39.to_s | Convert int. | Ruby |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
<p>value <b>test</p></b> | <p>value <b>test</b></p> | Nest properly. | HTML |
jwt.sign({{id:29}}, 'key'); | jwt.sign({{id:29}}, 'key', {{expiresIn:'7d'}}); | Add expiration. | Node.js |
foo = 71 | foo=71 | No spaces. | Shell |
["output", 46] | ["output", 46] | Correct. | JSON |
def process
puts 'result'
end | def process
puts 'result'
end | Correct. | Ruby |
WHERE email = '56' | WHERE email = 56 | Don't quote integer. | SQL |
cin >> bar; | int bar;
cin >> bar; | Declare variable. | C++ |
.User {{ color: #fff; }} | .User {{ color: #fff; }} | Correct. | CSS |
if result = 33 {{}} | if result == 33 {{}} | Use ==. | Swift |
print 'hello' | print 'hello'; | Add semicolon. | Perl |
const person:Person = {{name:'world'}}; | const person:Person = {{name:'world', age:12}}; | Add missing property. | TypeScript |
System.out.println('world') | System.out.println('world'); | Add semicolon. | Java |
print 'data' | print('data') | print needs parentheses. | Python |
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