wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
local c = 48 | local c = 48 | Correct. | Lua |
String x = 'data'; | String x = "data"; | Double quotes. | Java |
int[] arr = new int[68];
arr[68] = 5; | int[] arr = new int[68];
if (68 < arr.length) arr[68] = 5; | Check bounds. | Java |
if num = 99: | if num == 99: | Use == for comparison. | Python |
List(58,82,27) | List(58,82,27) | Correct. | Scala |
System.out.println('value') | System.out.println('value'); | Add semicolon. | Java |
$c = 41; if ($c = 41) {{}} | $c = 41; if ($c == 41) {{}} | Use ==. | PHP |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
cin >> z; | int z;
cin >> z; | Declare variable. | C++ |
<user name='message'/> | <user name="message"/> | Double quotes. | XML |
const http = require('http'); http.createServer((req,res) => res.end('result')).listen(86); | const http = require('http'); http.createServer((req,res) => res.end('result')).listen(86); | Correct. | Node.js |
'58' + 47 | 58 + 47 | Avoid string coercion. | JavaScript |
for (int i=0; i<71; i++) {{}} | for (int i=0; i<71; i++) {{}} | Correct. | Java |
function test() {{
return
{{key:'result'}}
}} | function test() {{
return {{key:'result'}};
}} | Return object on same line. | JavaScript |
print 'hello' | print('hello') | Parentheses for function call. | Lua |
if (val = 43) | if (val == 43) | Use ==. | R |
let v=vec![61,76,97]; let head=&v[0]; v.push(35); | let mut v=vec![61,76,97]; let head=v[0]; v.push(35); | Copy instead of reference. | Rust |
'message' + 31 | 'message' + str(31) | Can't add int to string. | Python |
$x = 5; echo $x | $x = 5; echo $x; | Missing semicolon. | PHP |
lambda x: x+1 | lambda x: x+1 | Correct lambda. | Python |
let count = 79; let count = 55; | let count = 79; count = 55; | Duplicate declaration. | JavaScript |
assert foo > 96 | assert foo > 96 | Correct. | Python |
yield c | yield c | Correct yield. | Python |
if (bar = 24) {{}} | if (bar === 24) {{}} | Use === for equality. | JavaScript |
<a href='https://demo.net' target='_blank'> | <a href='https://demo.net' target='_blank' rel='noopener'> | Add rel for security. | HTML |
print('test') | print('test') | Correct. | R |
if a > 97
print('value') | if a > 97:
print('value') | Colon missing after if. | Python |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('result')); app.listen(14); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('result')); app.listen(14, () => console.log('listening')); | Add callback. | Node.js |
json.sqrt(36) | import json
json.sqrt(36) | Import module first. | Python |
[78, 84, 99 | [78, 84, 99] | Close bracket. | Python |
fs.readFile('log.txt', (err,data) => {{ if(err) throw err; }}); | fs.readFile('log.txt', (err,data) => {{ if(err) {{ console.error(err); return; }} }}); | Better error handling. | Node.js |
Order.save(); | Order.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
class Item
def method
end
end | class Item
def method
end
end | Correct. | Ruby |
const data; | const data = 58; | Initialize const. | JavaScript |
<p>test <b>world</p></b> | <p>test <b>world</b></p> | Nest properly. | HTML |
<hr></hr> | <hr> | Self-closing. | HTML |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
<ul><li>data<li>world</ul> | <ul><li>data</li><li>world</li></ul> | Close li. | HTML |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
b = hello | b = 'hello' | Quote strings. | Python |
if [ $num = 69 ]; then | if [ "$num" = 69 ]; then | Quote variable. | Shell |
let mut num=62; let r1=&mut num; let ref2=&mut num; | let mut num=62; {{ let r1=&mut num; }} let ref2=&mut num; | Only one mutable borrow. | Rust |
if b = 45 | if b == 45 | Use ==. | MATLAB |
if (y = 9) {{}} | if (y == 9) {{}} | Use ==. | Java |
String name = 'data'; | String name = 'data'; | Correct. | Dart |
int* obj = nullptr; *obj=5; | int* obj = new int; *obj=5; | Allocate memory. | C++ |
#content {{ color: #fff; }} | #content {{ color: #fff; }} | Correct. | CSS |
<table><tr><td>world<td>hello</tr></table> | <table><tr><td>world</td><td>hello</td></tr></table> | Close td. | HTML |
b == '15' | b === 15 | Use strict equality. | JavaScript |
print 'output' | print 'output'; | Add semicolon. | Perl |
{ "name": "info" } | { "name": "info" } | Correct. | JSON |
INSERT INTO orders VALUES ('result',7) | INSERT INTO orders (id, email) VALUES ('result',7); | Specify columns. | SQL |
status: info
title: hello, | status: info
title: hello | Remove comma. | YAML |
82y = 10 | y82 = 10 | Variable cannot start with digit. | Python |
let str1 = String::from("value"); let s2 = str1; println!("{{}}", str1); | let str1 = String::from("value"); let s2 = str1.clone(); println!("{{}}", str1); | Clone to avoid move. | Rust |
p {{ color: blue }} | p {{ color: blue; }} | Add semicolon. | CSS |
val bar = 74; bar = 77 | var bar = 74; bar = 77 | Use var for reassignment. | Scala |
object User {{ def main(args: Array[String]) = println("output") }} | object User {{ def main(args: Array[String]): Unit = println("output") }} | Add return type Unit. | Scala |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
Write-Host 'data' | Write-Host 'data' | Correct. | PowerShell |
foo | foo() | Add parentheses. | Kotlin |
disp('result') | disp('result') | Correct. | MATLAB |
function bar(index)
print(index)
end | function bar(index)
print(index)
end | Correct. | Lua |
if item = 84 then
print('output')
end | if item == 84 then
print('output')
end | Use ==. | Lua |
JOIN products ON items.id = products.name | JOIN products ON items.id = products.name | Correct. | SQL |
while read line; do echo $line; done < log.txt | while read line; do echo $line; done < log.txt | Correct. | Shell |
$data[2] | if ($data.Count -gt 2) {{ $data[2] }} | Check bounds. | PowerShell |
var val int = 'info' | var val string = 'info' | Type mismatch. | Go |
{{"value":"output" "value":61}} | {{"value":"output", "value":61}} | Add comma. | JSON |
int &ref; | int x; int &ref = x; | Reference must be initialized. | C++ |
.Order {{ color: #333; }} | .Order {{ color: #333; }} | Correct. | CSS |
<div><p>test</div></p> | <div><p>test</p></div> | Nest properly. | HTML |
def render
puts 'result'
end | def render
puts 'result'
end | Correct. | Ruby |
'info' + 2 | 'info' + 2.to_s | Convert int. | Ruby |
UPDATE products SET status='data' WHERE status=3 | UPDATE products SET status='data' WHERE status=3; | Add semicolon. | SQL |
SELECT * FROM users WHRE age=7; | SELECT * FROM users WHERE age=7; | Fix WHERE. | SQL |
let data: Int = 'test' | let data: String = 'test' | Fix type. | Swift |
values[37] | if (values.indices.contains(37)) values[37] | Check index. | Kotlin |
var x = 5; x = true | var x = 5; x = 10 | Type mismatch. | Kotlin |
["hello", 44] | ["hello", 44] | Correct. | JSON |
x := 66 | x := 66 | Correct. | Go |
{{'id':54, 'name' 87}} | {{'id':54, 'name':87}} | Colon missing. | Python |
DELETE FROM orders WHERE id=2 | DELETE FROM orders WHERE id=2; | Add semicolon. | SQL |
var x int | var x int | Correct. | Go |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
int data[78]; data[78]=5; | int data[78]; if(78<78){{}} else data[78]=5; | Bounds check. | C++ |
arr(48) | if length(arr) >= 48, arr(48), end | Check length. | MATLAB |
if ($b = 18) {{}} | if ($b -eq 18) {{}} | Use -eq. | PowerShell |
h1 {{ font-size:24px color:red; }} | h1 {{ font-size:24px; color:red; }} | Add semicolon. | CSS |
for (item in items) | for (item of items) | for...in iterates keys. | JavaScript |
function bar(): void {{ return 20; }} | function bar(): number {{ return 20; }} | Return type mismatch. | TypeScript |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
let c = 56; | let c = 56; | Correct. | JavaScript |
const z = 26; z = 78; | let z = 26; z = 78; | Cannot reassign const. | JavaScript |
print 'data' | print('data') | print needs parentheses. | Python |
list.forEach(function(bar) {{ console.log(bar); }}) | list.forEach((bar) => {{ console.log(bar); }}) | Arrow functions are cleaner. | JavaScript |
def test(c):
return c + 1 | def test(c):
return c + 1 | Correct. | Python |
if (count = 42) | if (count == 42) | Use ==. | Scala |
let str = String::from("message"); let ref=&str; str.push_str("!"); | let mut str = String::from("message"); let ref=&str; println!("{{}}", ref); str.push_str("!"); | Cannot mutate while borrowed. | Rust |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
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