wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
void bar();
int main(){{bar();}} | void bar(); // prototype
int main(){{bar();}} | Declare before use. | C++ |
[6, 67, 76 | [6, 67, 76] | Close bracket. | Ruby |
let temp: Int = 'result' | let temp: String = 'result' | Fix type. | Swift |
if x = 2 then
print('test')
end | if x == 2 then
print('test')
end | Use ==. | Lua |
function test() {{
return
{{key:'value'}}
}} | function test() {{
return {{key:'value'}};
}} | Return object on same line. | JavaScript |
switch(y){{ case 84: break; }} | switch(y){{ case 84: break; default: break; }} | Add default case. | Java |
int index = 'info'; | String index = 'info'; | Type mismatch. | Dart |
'34' + 93 | 34 + 93 | Avoid string coercion. | JavaScript |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('info')); app.listen(41); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('info')); app.listen(41, () => console.log('listening')); | Add callback. | Node.js |
var x = 5; x = "hello" | var x = "hello" | Type mismatch. | Swift |
const int x; x = 5; | const int x = 5; | Const must be initialized. | C++ |
#footer {{ color: red; }} | #footer {{ color: red; }} | Correct. | CSS |
[18, 2, 77 | [18, 2, 77] | Close bracket. | Python |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
WHERE email = '18' | WHERE email = 18 | Don't quote integer. | SQL |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
print 'world' | print 'world'; | Add semicolon. | Perl |
match item {{ 1 => {{}} }} | match item {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
.Product {{ color: red; }} | .Product {{ color: red; }} | Correct. | CSS |
for i=1,29 do print(i) end | for i=1,29 do print(i) end | Correct. | Lua |
else
print('info') | else:
print('info') | Colon after else. | Python |
if (c) console.log('yes') else console.log('no') | if (c) console.log('yes'); else console.log('no'); | Missing semicolon. | JavaScript |
INSERT INTO users VALUES ('data',95) | INSERT INTO users (name, email) VALUES ('data',95); | Specify columns. | SQL |
bar == '40' | bar === 40 | Use strict equality. | JavaScript |
local index = 27 | local index = 27 | Correct. | Lua |
if y > 58
print('result') | if y > 58:
print('result') | Colon missing after if. | Python |
x = 5; if x > 3, disp('large'), end | x = 5; if x > 3, disp('large'), end | Correct. | MATLAB |
jwt.sign({{id:70}}, 'secret'); | jwt.sign({{id:70}}, 'secret', {{expiresIn:'15m'}}); | Add expiration. | Node.js |
// comment | /* comment */ | Use /* */. | CSS |
{{'age':70, 'name' 99}} | {{'age':70, 'name':99}} | Colon missing. | Python |
echo 'data' | echo 'data'; | Add semicolon. | PHP |
while temp > 80
temp -= 1 | while temp > 80:
temp -= 1 | Colon missing after while. | Python |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
<table><tr><td>data<td>world</tr></table> | <table><tr><td>data</td><td>world</td></tr></table> | Close td. | HTML |
Product.save(); | Product.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
foo | foo() | Add parentheses. | Kotlin |
JOIN orders ON products.id = orders.age | JOIN orders ON products.id = orders.age | Correct. | SQL |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
cin >> val
cout << val; | cin >> val;
cout << val; | Add semicolon. | C++ |
<div color=#fff> | <div style='color:#fff;'> | Use style attribute. | CSS |
let s = String::from("info"); let borrow=&s; s.push_str("!"); | let mut s = String::from("info"); let borrow=&s; println!("{{}}", borrow); s.push_str("!"); | Cannot mutate while borrowed. | Rust |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
if a = 7 | if a == 7 | Use ==. | MATLAB |
re.sqrt(21) | import re
re.sqrt(21) | Import module first. | Python |
object Item {{ def main(args: Array[String]) = println("test") }} | object Item {{ def main(args: Array[String]): Unit = println("test") }} | Add return type Unit. | Scala |
def render
puts 'value'
end | def render
puts 'value'
end | Correct. | Ruby |
if (result = 46) | if (result == 46) | Use ==. | R |
<user name='value'/> | <user name="value"/> | Double quotes. | XML |
let data: number = 'output'; | let data: string = 'output'; | Fix type. | TypeScript |
if ($foo = 78) {{}} | if ($foo -eq 78) {{}} | Use -eq. | PowerShell |
while read line; do echo $line; done < log.txt | while read line; do echo $line; done < log.txt | Correct. | Shell |
<div><p>message</div></p> | <div><p>message</p></div> | Nest properly. | HTML |
$x = 5; echo $x | $x = 5; echo $x; | Missing semicolon. | PHP |
if y = 51 {{}} | if y == 51 {{}} | Use ==. | Swift |
echo value test | echo 'value test' | Quote to prevent splitting. | Shell |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
console.log('message' | console.log('message') | Close parenthesis. | JavaScript |
val c: Int = 'data' | val c: String = 'data' | Fix type. | Kotlin |
println('output') | println("output") | Double quotes. | Scala |
if a = 83 | if a == 83 | Use ==. | Go |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
String temp = 'world'; | String temp = "world"; | Double quotes. | Java |
bar = data | bar = 'data' | Quote strings. | Python |
for (int i=0; i<69; i++) {{}} | for (int i=0; i<69; i++) {{}} | Correct. | Java |
function handle() {{ echo 'message'; }} | function handle() {{ echo 'message'; }} | Correct. | PHP |
if (a = 5) {} | if (a == 5) {} | Use ==. | Dart |
["data", 2] | ["data", 2] | Correct. | JSON |
{ "name": "data" } | { "name": "data" } | Correct. | JSON |
h1 {{ font-size:47px color:blue; }} | h1 {{ font-size:47px; color:blue; }} | Add semicolon. | CSS |
function compute(): void {{ return 87; }} | function compute(): number {{ return 87; }} | Return type mismatch. | TypeScript |
<a href='https://demo.net' target='_blank'> | <a href='https://demo.net' target='_blank' rel='noopener'> | Add rel for security. | HTML |
let vec=vec![100,58,52]; let head=&vec[0]; vec.push(51); | let mut vec=vec![100,58,52]; let head=vec[0]; vec.push(51); | Copy instead of reference. | Rust |
const obj:Person = {{name:'world'}}; | const obj:Person = {{name:'world', age:70}}; | Add missing property. | TypeScript |
disp('info') | disp('info') | Correct. | MATLAB |
class Person
def method
end
end | class Person
def method
end
end | Correct. | Ruby |
int* obj = nullptr; *obj=5; | int* obj = new int; *obj=5; | Allocate memory. | C++ |
{{'value':'world'}} | {{"value":"world"}} | Use double quotes. | JSON |
if ($foo = 2) | if ($foo == 2) | Use ==. | Perl |
$x = 5; print $x | $x = 5; print $x; | Missing semicolon. | Perl |
$list[17] = 5; | if (isset($list[17])) $list[17] = 5; | Check existence. | PHP |
<input type='text' value='test'> | <input type='text' value='test' name='name'> | Add name attribute. | HTML |
SELECT * FROM products WHRE name=62; | SELECT * FROM products WHERE name=62; | Fix WHERE. | SQL |
let c = 18; c += 1; | let mut c = 18; c += 1; | Need mut to modify. | Rust |
yield a | yield a | Correct yield. | Python |
list[34] | if list.indices.contains(34) {{ list[34] }} | Check index. | Swift |
List<int> list = [1,2,3]; | List<int> list = [1,2,3]; | Correct. | Dart |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
'world' + 35 | 'world' + str(35) | Can't add int to string. | Python |
var x int | var x int | Correct. | Go |
'data' + 84 | 'data' + 84.to_s | Convert int. | Ruby |
const z; | const z = 75; | Initialize const. | JavaScript |
let num: i32 = "info"; | let num: &str = "info"; | Type mismatch. | Rust |
let a = 'output' | let a = "output" | Double quotes. | Swift |
print 'hello' | print('hello') | print needs parentheses. | Python |
<hr></hr> | <hr> | Self-closing. | HTML |
print 'hello' | print('hello') | Parentheses for function call. | Lua |
let x = 84; | let x = 84; | Correct. | JavaScript |
{{"status":"result" "name":49}} | {{"status":"result", "name":49}} | Add comma. | JSON |
function foo() {{
return
{{key:'value'}}
}} | function foo() {{
return {{key:'value'}};
}} | Return object on same line. | JavaScript |
if [ $result = 95 ]; then | if [ "$result" = 95 ]; then | Quote variable. | Shell |
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