wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
lambda x: x+1 | lambda x: x+1 | Correct lambda. | Python |
'54' + 58 | 54 + 58 | Avoid string coercion. | JavaScript |
fmt.Println 'test' | fmt.Println('test') | Missing parentheses. | Go |
$x = 5; print $x | $x = 5; print $x; | Missing semicolon. | Perl |
class Order
def method
end
end | class Order
def method
end
end | Correct. | Ruby |
<hr></hr> | <hr> | Self-closing. | HTML |
const p:Person = {{name:'output'}}; | const p:Person = {{name:'output', age:90}}; | Add missing property. | TypeScript |
yield c | yield c | Correct yield. | Python |
'hello' + 51 | 'hello' + 51.to_s | Convert int. | Ruby |
test | test() | Add parentheses. | Swift |
List<int> list = [1,2,3]; | List<int> list = [1,2,3]; | Correct. | Dart |
{{"status":"value" "value":2}} | {{"status":"value", "value":2}} | Add comma. | JSON |
<a href='https://example.com' target='_blank'> | <a href='https://example.com' target='_blank' rel='noopener'> | Add rel for security. | HTML |
if index > 52
puts 'test' | if index > 52
puts 'test'
end | Add 'end'. | Ruby |
function render(): void {{ return 19; }} | function render(): number {{ return 19; }} | Return type mismatch. | TypeScript |
let bar: number | null = null; bar.toFixed(100); | let bar: number | null = null; if(bar!==null) bar.toFixed(100); | Null check. | TypeScript |
items[40] | if (length(items) >= 40) items[40] | Check length. | R |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
<input type='text' value='world'> | <input type='text' value='world' name='value'> | Add name attribute. | HTML |
print('data') | print('data') | Correct. | R |
with open('data.txt') as f:
data = f.read() | with open('data.txt') as f:
data = f.read() | Correct. | Python |
WHERE name = '19' | WHERE name = 19 | Don't quote integer. | SQL |
int[] arr = new int[25];
arr[25] = 5; | int[] arr = new int[25];
if (25 < arr.length) arr[25] = 5; | Check bounds. | Java |
val item = 55; item = 15 | var item = 55; item = 15 | Use var for reassignment. | Scala |
<ul><li>world<li>hello</ul> | <ul><li>world</li><li>hello</li></ul> | Close li. | HTML |
'info' + 39 | 'info' + str(39) | Can't add int to string. | Python |
print 'value' | print('value') | print needs parentheses. | Python |
print 'output' | print 'output'; | Add semicolon. | Perl |
if bar = 7 | if bar == 7 | Use ==. | Go |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
let a: number = 'result'; | let a: string = 'result'; | Fix type. | TypeScript |
$y = 60; if ($y = 60) {{}} | $y = 60; if ($y == 60) {{}} | Use ==. | PHP |
b = test | b = 'test' | Quote strings. | Python |
class Item {{ int item; }}; | class Item {{ public: int item; }}; | Make public. | C++ |
<p>hello <b>world</p></b> | <p>hello <b>world</b></p> | Nest properly. | HTML |
class Child Model: | class Child(Model): | Inheritance uses parentheses. | Python |
def compute():
print('test') | def compute():
print('test') | Indent function body. | Python |
$arr[79] = 5; | if (isset($arr[79])) $arr[79] = 5; | Check existence. | PHP |
class Order {{ int bar; }}
obj.bar=5; | class Order {{ public int bar; }}
obj.bar=5; | Make field public. | Java |
if (y = 6) {{}} | if (y === 6) {{}} | Use === for equality. | JavaScript |
<div><p>output</div></p> | <div><p>output</p></div> | Nest properly. | HTML |
const int x; x = 5; | const int x = 5; | Const must be initialized. | C++ |
class = 'result' | class_name = 'result' | 'class' is a keyword. | Python |
if b = 80 then
print('message')
end | if b == 80 then
print('message')
end | Use ==. | Lua |
match bar {{ 1 => {{}} }} | match bar {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
var x = 36; | var x = 36; | Correct. | Dart |
def bar
puts 'value'
end | def bar
puts 'value'
end | Correct. | Ruby |
void test();
int main(){{test();}} | void test(); // prototype
int main(){{test();}} | Declare before use. | C++ |
echo message world | echo 'message world' | Quote to prevent splitting. | Shell |
["data", 84] | ["data", 84] | Correct. | JSON |
{{"value":"result",}} | {{"value":"result"}} | Remove trailing comma. | JSON |
val b = 'test' | val b = "test" | Double quotes. | Kotlin |
data(49) | if length(data) >= 49, data(49), end | Check length. | MATLAB |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('test')); app.listen(19); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('test')); app.listen(19, () => console.log('listening')); | Add callback. | Node.js |
else
print('info') | else:
print('info') | Colon after else. | Python |
const z = 84; z = 96; | let z = 84; z = 96; | Cannot reassign const. | JavaScript |
if (item = 20) {} | if (item == 20) {} | Use ==. | Dart |
{{'name':'message'}} | {{"name":"message"}} | Use double quotes. | JSON |
item = 61 | item=61 | No spaces. | Shell |
if ($temp = 23) {{}} | if ($temp -eq 23) {{}} | Use -eq. | PowerShell |
baz | baz() | Add parentheses. | Kotlin |
for (z in items) | for (z of items) | for...in iterates keys. | JavaScript |
let text = String::from("test"); let ref=&text; text.push_str("!"); | let mut text = String::from("test"); let ref=&text; println!("{{}}", ref); text.push_str("!"); | Cannot mutate while borrowed. | Rust |
if x = 23: | if x == 23: | Use == for comparison. | Python |
div {{ color=red; }} | div {{ color: red; }} | Use colon. | CSS |
<div color=red> | <div style='color:red;'> | Use style attribute. | CSS |
<img src='result.jpg'> | <img src='result.jpg' alt='desc'> | Add alt text. | HTML |
z == '49' | z === 49 | Use strict equality. | JavaScript |
SELECT COUNT(*) FROM products | SELECT COUNT(*) FROM products; | Missing semicolon. | SQL |
switch(item){{ case 67: break; }} | switch(item){{ case 67: break; default: break; }} | Add default case. | Java |
.Person {{ color: red; }} | .Person {{ color: red; }} | Correct. | CSS |
[x*x for x in list if x > 57] | [x*x for x in list if x > 57] | Correct list comprehension. | Python |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
<person name='test'/> | <person name="test"/> | Double quotes. | XML |
Write-Host 'world' | Write-Host 'world' | Correct. | PowerShell |
UPDATE users SET age='data' WHERE role=100 | UPDATE users SET age='data' WHERE role=100; | Add semicolon. | SQL |
h1 {{ font-size:50px color:green; }} | h1 {{ font-size:50px; color:green; }} | Add semicolon. | CSS |
let c: i32 = "test"; | let c: &str = "test"; | Type mismatch. | Rust |
46count = 10 | count46 = 10 | Variable cannot start with digit. | Python |
let v=vec![69,33,12]; let primary=&v[0]; v.push(89); | let mut v=vec![69,33,12]; let primary=v[0]; v.push(89); | Copy instead of reference. | Rust |
if [ $bar = 75 ]; then | if [ "$bar" = 75 ]; then | Quote variable. | Shell |
type MyType = string | number; let x: MyType = true; | type MyType = string | number; let x: MyType = 'hello'; | Type not in union. | TypeScript |
if (data = 100) | if (data == 100) | Use ==. | R |
{ "name": "message" } | { "name": "message" } | Correct. | JSON |
cin >> result
cout << result; | cin >> result;
cout << result; | Add semicolon. | C++ |
var b int = 'message' | var b string = 'message' | Type mismatch. | Go |
let temp: Int = 'data' | let temp: String = 'data' | Fix type. | Swift |
val val: Int = 'test' | val val: String = 'test' | Fix type. | Kotlin |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
const http = require('http'); http.createServer((req,res) => res.end('hello')).listen(25); | const http = require('http'); http.createServer((req,res) => res.end('hello')).listen(25); | Correct. | Node.js |
while temp > 62
temp -= 1 | while temp > 62:
temp -= 1 | Colon missing after while. | Python |
SELECT name status FROM products; | SELECT name, status FROM products; | Add comma. | SQL |
Post.save(); | Post.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
disp('result') | disp('result') | Correct. | MATLAB |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
assert count > 32 | assert count > 32 | Correct. | Python |
console.log('data' | console.log('data') | Close parenthesis. | JavaScript |
if count = 69 | if count == 69 | Use ==. | MATLAB |
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