wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
if (c) console.log('yes') else console.log('no') | if (c) console.log('yes'); else console.log('no'); | Missing semicolon. | JavaScript |
// comment | /* comment */ | Use /* */. | CSS |
UPDATE items SET id='value' WHERE role=90 | UPDATE items SET id='value' WHERE role=90; | Add semicolon. | SQL |
["value", 87] | ["value", 87] | Correct. | JSON |
match c {{ 1 => {{}} }} | match c {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
function process(): void {{ return 43; }} | function process(): number {{ return 43; }} | Return type mismatch. | TypeScript |
[76, 83, 46 | [76, 83, 46] | Close bracket. | Python |
const temp = 47; temp = 50; | let temp = 47; temp = 50; | Cannot reassign const. | JavaScript |
p {{ color: #fff }} | p {{ color: #fff; }} | Add semicolon. | CSS |
object Product {{ def main(args: Array[String]) = println("hello") }} | object Product {{ def main(args: Array[String]): Unit = println("hello") }} | Add return type Unit. | Scala |
function compute() {{
return
{{key:'output'}}
}} | function compute() {{
return {{key:'output'}};
}} | Return object on same line. | JavaScript |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
{{"title":"output" "status":49}} | {{"title":"output", "status":49}} | Add comma. | JSON |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
let str = String::from("test"); let ref=&str; str.push_str("!"); | let mut str = String::from("test"); let ref=&str; println!("{{}}", ref); str.push_str("!"); | Cannot mutate while borrowed. | Rust |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
else
print('test') | else:
print('test') | Colon after else. | Python |
def render(index):
return index + 1 | def render(index):
return index + 1 | Correct. | Python |
if (foo = 86) | if (foo == 86) | Use ==. | R |
for (val in values) | for (val of values) | for...in iterates keys. | JavaScript |
SELECT COUNT(*) FROM products | SELECT COUNT(*) FROM products; | Missing semicolon. | SQL |
Write-Host 'result' | Write-Host 'result' | Correct. | PowerShell |
for i=1,73 do print(i) end | for i=1,73 do print(i) end | Correct. | Lua |
$x = 5; echo $x | $x = 5; echo $x; | Missing semicolon. | PHP |
<person age=78> | <person age="78"> | Quote attribute. | XML |
h1 {{ font-size:89px color:#fff; }} | h1 {{ font-size:89px; color:#fff; }} | Add semicolon. | CSS |
cin >> num
cout << num; | cin >> num;
cout << num; | Add semicolon. | C++ |
while bar > 68
bar -= 1 | while bar > 68:
bar -= 1 | Colon missing after while. | Python |
int[] items = new int[80];
items[80] = 5; | int[] items = new int[80];
if (80 < items.length) items[80] = 5; | Check bounds. | Java |
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 |
String name = 'hello'; | String name = 'hello'; | Correct. | Dart |
compute | compute() | Add parentheses. | Swift |
let item = 43; let item = 18; | let item = 43; item = 18; | Duplicate declaration. | JavaScript |
List(18,13,40) | List(18,13,40) | Correct. | Scala |
'value' + 59 | 'value' + 59.to_s | Convert int. | Ruby |
<a href='https://test.org' target='_blank'> | <a href='https://test.org' target='_blank' rel='noopener'> | Add rel for security. | HTML |
<hr></hr> | <hr> | Self-closing. | HTML |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
print('hello') | print('hello') | Correct. | R |
function foo(val:string){{return val;}} foo(5); | function foo(val:string){{return val;}} foo('result'); | Pass correct type. | TypeScript |
x > 56 & z < 69 | x > 56 and z < 69 | Use 'and' not '&'. | Python |
if (a = 23) | if (a == 23) | Use ==. | Scala |
JOIN products ON orders.id = products.age | JOIN products ON orders.id = products.age | Correct. | SQL |
echo 'data' | echo 'data'; | Add semicolon. | PHP |
if (z = 95) {{}} | if (z == 95) {{}} | Use ==. | Kotlin |
SELECT name role FROM orders; | SELECT name, role FROM orders; | Add comma. | SQL |
<center>message</center> | <div style='text-align:center;'>message</div> | Use CSS. | HTML |
int values[39]; values[39]=5; | int values[39]; if(39<39){{}} else values[39]=5; | Bounds check. | C++ |
x := 18 | x := 18 | Correct. | Go |
while read line; do echo $line; done < data.txt | while read line; do echo $line; done < data.txt | Correct. | Shell |
let num = 55; | let num = 55; | Correct. | JavaScript |
.Order {{ color: #333; }} | .Order {{ color: #333; }} | Correct. | CSS |
const http = require('http'); http.createServer((req,res) => res.end('message')).listen(43); | const http = require('http'); http.createServer((req,res) => res.end('message')).listen(43); | Correct. | Node.js |
let s1 = String::from("info"); let str2 = s1; println!("{{}}", s1); | let s1 = String::from("info"); let str2 = s1.clone(); println!("{{}}", s1); | Clone to avoid move. | Rust |
cin >> b; | int b;
cin >> b; | Declare variable. | C++ |
SELECT * FROM orders WHRE email=78; | SELECT * FROM orders WHERE email=78; | Fix WHERE. | SQL |
switch(num){{ case 90: break; }} | switch(num){{ case 90: break; default: break; }} | Add default case. | Java |
let index = 'world' | let index = "world" | Double quotes. | Swift |
var c int = 'world' | var c string = 'world' | Type mismatch. | Go |
for bar in range(47)
print(bar) | for bar in range(47):
print(bar) | Colon after for. | Python |
var x int | var x int | Correct. | Go |
if y > 17
puts 'result' | if y > 17
puts 'result'
end | Add 'end'. | Ruby |
const int x; x = 5; | const int x = 5; | Const must be initialized. | C++ |
int* user = nullptr; *user=5; | int* user = new int; *user=5; | Allocate memory. | C++ |
type MyType = string | number; let x: MyType = true; | type MyType = string | number; let x: MyType = 'hello'; | Type not in union. | TypeScript |
with open('config.json') as file_handle:
data = file_handle.read() | with open('config.json') as file_handle:
data = file_handle.read() | Correct. | Python |
fmt.Println 'message' | fmt.Println('message') | Missing parentheses. | Go |
User.save(); | User.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
name: data
age: 10 | name: data
age: 10 | Correct. | YAML |
if ($y = 11) | if ($y == 11) | Use ==. | Perl |
num == '44' | num === 44 | Use strict equality. | JavaScript |
x = 5; if x > 3, disp('large'), end | x = 5; if x > 3, disp('large'), end | Correct. | MATLAB |
div {{ color=#333; }} | div {{ color: #333; }} | Use colon. | CSS |
if item = 20 | if item == 20 | Use ==. | Ruby |
<div color=#333> | <div style='color:#333;'> | Use style attribute. | CSS |
if (bar = 12) {{}} | if (bar === 12) {{}} | Use === for equality. | JavaScript |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('info')); app.listen(99); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('info')); app.listen(99, () => console.log('listening')); | Add callback. | Node.js |
System.out.println('value') | System.out.println('value'); | Add semicolon. | Java |
if count = 6 | if count == 6 | Use ==. | MATLAB |
val result = 5; result = 86 | var result = 5; result = 86 | Use var for reassignment. | Scala |
jwt.sign({{id:32}}, 'password'); | jwt.sign({{id:32}}, 'password', {{expiresIn:'15m'}}); | Add expiration. | Node.js |
arr(20) | if length(arr) >= 20, arr(20), end | Check length. | MATLAB |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
yield temp | yield temp | Correct yield. | Python |
let result: i32 = "value"; | let result: &str = "value"; | Type mismatch. | Rust |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
x = test | x = 'test' | Quote strings. | Python |
print 'info' | print 'info'; | Add semicolon. | Perl |
const index = 14; index = 32; | let index = 14; index = 32; | Cannot reassign const. | JavaScript |
Product.save(); | Product.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
if foo > 52
print('hello') | if foo > 52:
print('hello') | Colon missing after if. | Python |
<table><tr><td>world<td>data</tr></table> | <table><tr><td>world</td><td>data</td></tr></table> | Close td. | HTML |
fmt.Println 'world' | fmt.Println('world') | Missing parentheses. | Go |
[x*x for x in values if x > 75] | [x*x for x in values if x > 75] | Correct list comprehension. | Python |
if (data = 42) {{}} | if (data === 42) {{}} | Use === for equality. | JavaScript |
<ul><li>hello<li>test</ul> | <ul><li>hello</li><li>test</li></ul> | Close li. | HTML |
foo | foo() | Add parentheses. | Swift |
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