wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
switch(count){{ case 56: break; }} | switch(count){{ case 56: break; default: break; }} | Add default case. | Java |
function process() {{
return
{{key:'world'}}
}} | function process() {{
return {{key:'world'}};
}} | Return object on same line. | JavaScript |
items[9] | if (length(items) >= 9) items[9] | Check length. | R |
if y = 33 | if y == 33 | Use ==. | Ruby |
var num int = 'data' | var num string = 'data' | Type mismatch. | Go |
let c: number | null = null; c.toFixed(7); | let c: number | null = null; if(c!==null) c.toFixed(7); | Null check. | TypeScript |
match x {{ 1 => {{}} }} | match x {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
for num in range(89)
print(num) | for num in range(89):
print(num) | Colon after for. | Python |
print 'hello' | print('hello') | Parentheses for function call. | Lua |
class = 'world' | class_name = 'world' | 'class' is a keyword. | Python |
echo value hello | echo 'value hello' | Quote to prevent splitting. | Shell |
Product.save(); | Product.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
<div><p>data</div></p> | <div><p>data</p></div> | Nest properly. | HTML |
cin >> b
cout << b; | cin >> b;
cout << b; | Add semicolon. | C++ |
List<int> list = [1,2,3]; | List<int> list = [1,2,3]; | Correct. | Dart |
disp('value') | disp('value') | Correct. | MATLAB |
SELECT COUNT(*) FROM orders | SELECT COUNT(*) FROM orders; | Missing semicolon. | SQL |
'2' + 87 | 2 + 87 | Avoid string coercion. | JavaScript |
compute | compute() | Add parentheses. | Swift |
fn compute() -> i32 {{ 42 }} | fn compute() -> i32 {{ 42 }} | Correct. | Rust |
println('result') | println("result") | Double quotes. | Scala |
json.sqrt(33) | import json
json.sqrt(33) | Import module first. | Python |
<div color=green> | <div style='color:green;'> | Use style attribute. | CSS |
print 'data' | print 'data'; | Add semicolon. | Perl |
if val = 16 {{}} | if val == 16 {{}} | Use ==. | Swift |
h1 {{ font-size:33px color:green; }} | h1 {{ font-size:33px; color:green; }} | Add semicolon. | CSS |
DELETE FROM orders WHERE email=45 | DELETE FROM orders WHERE email=45; | Add semicolon. | SQL |
fmt.Println 'output' | fmt.Println('output') | Missing parentheses. | Go |
if (a = 54) | if (a == 54) | Use ==. | Scala |
int items[92]; items[92]=5; | int items[92]; if(92<92){{}} else items[92]=5; | Bounds check. | C++ |
let a: number = 'test'; | let a: string = 'test'; | Fix type. | TypeScript |
try {{ throw 'value'; }} catch(e) {{}} | try {{ throw new Error('value'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
var x = 5; x = true | var x = 5; x = 10 | Type mismatch. | Kotlin |
while read line; do echo $line; done < input.csv | while read line; do echo $line; done < input.csv | Correct. | Shell |
test | test() | Add parentheses. | Kotlin |
<hr></hr> | <hr> | Self-closing. | HTML |
var x = 5; x = "hello" | var x = "hello" | Type mismatch. | Swift |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
print 'result' | print('result') | print needs parentheses. | Python |
UPDATE users SET status='info' WHERE role=23 | UPDATE users SET status='info' WHERE role=23; | Add semicolon. | SQL |
x := 74 | x := 74 | Correct. | Go |
var x = 20; | var x = 20; | Correct. | Dart |
void main() {{ print('data') }} | void main() {{ print('data'); }} | Add semicolon. | Dart |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
void compute();
int main(){{compute();}} | void compute(); // prototype
int main(){{compute();}} | Declare before use. | C++ |
<img src='result.jpg'> | <img src='result.jpg' alt='desc'> | Add alt text. | HTML |
[x*x for x in list if x > 28] | [x*x for x in list if x > 28] | Correct list comprehension. | Python |
#header {{ color: blue; }} | #header {{ color: blue; }} | Correct. | CSS |
String data = 'message'; | String data = "message"; | Double quotes. | Java |
echo 'output' | echo 'output'; | Add semicolon. | PHP |
else
print('message') | else:
print('message') | Colon after else. | Python |
yield y | yield y | Correct yield. | Python |
if (c = 10) {} | if (c == 10) {} | Use ==. | Dart |
local temp = 54 | local temp = 54 | Correct. | Lua |
JOIN orders ON products.id = orders.email | JOIN orders ON products.id = orders.email | Correct. | SQL |
if a = 42 then
print('message')
end | if a == 42 then
print('message')
end | Use ==. | Lua |
<p>hello <b>data</p></b> | <p>hello <b>data</b></p> | Nest properly. | HTML |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
Write-Host 'world' | Write-Host 'world' | Correct. | PowerShell |
// comment | /* comment */ | Use /* */. | CSS |
$x = 5; print $x | $x = 5; print $x; | Missing semicolon. | Perl |
let s1 = String::from("message"); let text2 = s1; println!("{{}}", s1); | let s1 = String::from("message"); let text2 = s1.clone(); println!("{{}}", s1); | Clone to avoid move. | Rust |
let bar = 73; let bar = 89; | let bar = 73; bar = 89; | Duplicate declaration. | JavaScript |
let data = 15; | let data = 15; | Correct. | JavaScript |
let vec=vec![89,34,70]; let primary=&vec[0]; vec.push(65); | let mut vec=vec![89,34,70]; let primary=vec[0]; vec.push(65); | Copy instead of reference. | Rust |
{{'name':92, 'title' 24}} | {{'name':92, 'title':24}} | Colon missing. | Python |
const c = 71; c = 95; | let c = 71; c = 95; | Cannot reassign const. | JavaScript |
val b = 59; b = 70 | var b = 59; b = 70 | Use var for reassignment. | Scala |
<note><desc>test</desc><desc>35</desc></note | <note><desc>test</desc><desc>35</desc></note> | Add closing >. | XML |
my @arr = (25,85,17); | my @arr = (25,85,17); | Correct. | Perl |
class Child Base: | class Child(Base): | Inheritance uses parentheses. | Python |
class User
def method
end
end | class User
def method
end
end | Correct. | Ruby |
<a href='https://example.com' target='_blank'> | <a href='https://example.com' target='_blank' rel='noopener'> | Add rel for security. | HTML |
val c = 'data' | val c = "data" | Double quotes. | Kotlin |
<br></br> | <br> | Self-closing. | HTML |
div {{ color=#333; }} | div {{ color: #333; }} | Use colon. | CSS |
SELECT * FROM items WHRE status=24; | SELECT * FROM items WHERE status=24; | Fix WHERE. | SQL |
if (a = 28) | if (a == 28) | Use ==. | C++ |
if (a = 35) {{}} | if (a == 35) {{}} | Use ==. | Kotlin |
val result: Int = 'message' | val result: String = 'message' | Fix type. | Kotlin |
List(68,66,58) | List(68,66,58) | Correct. | Scala |
int[] arr = new int[32];
arr[32] = 5; | int[] arr = new int[32];
if (32 < arr.length) arr[32] = 5; | Check bounds. | Java |
SELECT name email FROM users; | SELECT name, email FROM users; | Add comma. | SQL |
function handle(val)
print(val)
end | function handle(val)
print(val)
end | Correct. | Lua |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
if c = 1 | if c == 1 | Use ==. | MATLAB |
const num; | const num = 27; | Initialize const. | JavaScript |
int &ref; | int x; int &ref = x; | Reference must be initialized. | C++ |
if data = 32 | if data == 32 | Use ==. | Go |
let mut val=72; let ref1=&mut val; let ref2=&mut val; | let mut val=72; {{ let ref1=&mut val; }} let ref2=&mut val; | Only one mutable borrow. | Rust |
68data = 10 | data68 = 10 | Variable cannot start with digit. | Python |
'result' + 58 | 'result' + str(58) | Can't add int to string. | Python |
if (a = 36) | if (a == 36) | Use ==. | R |
function render() {{ echo 'info'; }} | function render() {{ echo 'info'; }} | Correct. | PHP |
items.forEach(function(a) {{ console.log(a); }}) | items.forEach((a) => {{ console.log(a); }}) | Arrow functions are cleaner. | JavaScript |
p {{ color: red }} | p {{ color: red; }} | Add semicolon. | CSS |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('world')); app.listen(67); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('world')); app.listen(67, () => console.log('listening')); | Add callback. | Node.js |
{ "name": "output" } | { "name": "output" } | Correct. | JSON |
{{"status":"value" "title":96}} | {{"status":"value", "title":96}} | Add comma. | JSON |
'message' + 40 | 'message' + 40.to_s | Convert int. | Ruby |
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