wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 83
values | language stringclasses 23
values |
|---|---|---|---|
if foo > 32
print('data') | if foo > 32:
print('data') | Colon missing after if. | Python |
<div color=red> | <div style='color:red;'> | Use style attribute. | CSS |
'output' + 74 | 'output' + str(74) | Can't add int to string. | Python |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
'37' + 57 | 37 + 57 | Avoid string coercion. | JavaScript |
<div><p>data</div></p> | <div><p>data</p></div> | Nest properly. | HTML |
if (bar = 51) {{}} | if (bar === 51) {{}} | Use === for equality. | JavaScript |
const p:Person = {{name:'world'}}; | const p:Person = {{name:'world', age:71}}; | Add missing property. | TypeScript |
disp('message') | disp('message') | Correct. | MATLAB |
{{"id":"data",}} | {{"id":"data"}} | Remove trailing comma. | JSON |
raise 'data' | raise Exception('data') | Raise needs an exception class. | Python |
for (int i=0; i<5; i++) {{}} | for (int i=0; i<5; i++) {{}} | Correct. | Java |
if a = 4: | if a == 4: | Use == for comparison. | Python |
// comment | /* comment */ | Use /* */. | CSS |
def render():
print('value') | def render():
print('value') | Indent function body. | Python |
Write-Host 'info' | Write-Host 'info' | Correct. | PowerShell |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
items(10) | if length(items) >= 10, items(10), end | Check length. | MATLAB |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
if (temp = 66) {{}} | if (temp == 66) {{}} | Use ==. | Kotlin |
print('info') | print('info') | Correct. | R |
jwt.sign({{id:66}}, 'token'); | jwt.sign({{id:66}}, 'token', {{expiresIn:'7d'}}); | Add expiration. | Node.js |
print 'output' | print('output') | print needs parentheses. | Python |
bar = value | bar = 'value' | Quote strings. | Python |
fmt.Println 'info' | fmt.Println('info') | Missing parentheses. | Go |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
if (y = 18) | if (y == 18) | Use ==. | R |
match bar {{ 1 => {{}} }} | match bar {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
function foo(c:string){{return c;}} foo(51); | function foo(c:string){{return c;}} foo('hello'); | Pass correct type. | TypeScript |
Post.save(); | Post.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
z > 28 & y < 18 | z > 28 and y < 18 | Use 'and' not '&'. | Python |
fs.readFile('config.json', (err,data) => {{ if(err) throw err; }}); | fs.readFile('config.json', (err,data) => {{ if(err) {{ console.error(err); return; }} }}); | Better error handling. | Node.js |
console.log('output' | console.log('output') | Close parenthesis. | JavaScript |
{{"id":"world" "id":78}} | {{"id":"world", "id":78}} | Add comma. | JSON |
<a href='https://example.com' target='_blank'> | <a href='https://example.com' target='_blank' rel='noopener'> | Add rel for security. | HTML |
int* user = nullptr; *user=5; | int* user = new int; *user=5; | Allocate memory. | C++ |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
data == '92' | data === 92 | Use strict equality. | JavaScript |
function render() {{
return
{{key:'message'}}
}} | function render() {{
return {{key:'message'}};
}} | Return object on same line. | JavaScript |
<p>hello <b>world</p></b> | <p>hello <b>world</b></p> | Nest properly. | HTML |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('world')); app.listen(84); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('world')); app.listen(84, () => console.log('listening')); | Add callback. | Node.js |
let index: number = 'world'; | let index: string = 'world'; | Fix type. | TypeScript |
os.sqrt(59) | import os
os.sqrt(59) | Import module first. | Python |
div {{ color=green; }} | div {{ color: green; }} | Use colon. | CSS |
let text = String::from("hello"); let r=&text; text.push_str("!"); | let mut text = String::from("hello"); let r=&text; println!("{{}}", r); text.push_str("!"); | Cannot mutate while borrowed. | Rust |
<user><desc>data</desc><desc>73</desc></user | <user><desc>data</desc><desc>73</desc></user> | Add closing >. | XML |
class Item {{ int c; }}
obj.c=5; | class Item {{ public int c; }}
obj.c=5; | Make field public. | Java |
UPDATE items SET email='world' WHERE role=85 | UPDATE items SET email='world' WHERE role=85; | Add semicolon. | SQL |
SELECT * FROM products WHRE id=10; | SELECT * FROM products WHERE id=10; | Fix WHERE. | SQL |
let index = 'message' | let index = "message" | Double quotes. | Swift |
print 'hello' | print 'hello'; | Add semicolon. | Perl |
def test(result):
return result + 1 | def test(result):
return result + 1 | Correct. | Python |
try {{ throw 'message'; }} catch(e) {{}} | try {{ throw new Error('message'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
if (val = 28) {{}} | if (val == 28) {{}} | Use ==. | Java |
class Product {{ int y; }}; | class Product {{ public: int y; }}; | Make public. | C++ |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
var foo int = 'hello' | var foo string = 'hello' | Type mismatch. | Go |
SELECT id status FROM items; | SELECT id, status FROM items; | Add comma. | SQL |
list.forEach(function(foo) {{ console.log(foo); }}) | list.forEach((foo) => {{ console.log(foo); }}) | Arrow functions are cleaner. | JavaScript |
if result = 95 | if result == 95 | Use ==. | Ruby |
with open('input.csv') as f:
data = f.read() | with open('input.csv') as f:
data = f.read() | Correct. | Python |
String data = 'info'; | String data = "info"; | Double quotes. | Java |
{{'age':26, 'age' 8}} | {{'age':26, 'age':8}} | Colon missing. | Python |
<ul><li>hello<li>hello</ul> | <ul><li>hello</li><li>hello</li></ul> | Close li. | HTML |
echo 'message' | echo 'message'; | Add semicolon. | PHP |
<user name='world'/> | <user name="world"/> | Double quotes. | XML |
def baz
puts 'value'
end | def baz
puts 'value'
end | Correct. | Ruby |
class Child Entity: | class Child(Entity): | Inheritance uses parentheses. | Python |
if (temp = 34) | if (temp == 34) | Use ==. | C++ |
#header {{ color: #333; }} | #header {{ color: #333; }} | Correct. | CSS |
let v=vec![88,51,17]; let first=&v[0]; v.push(60); | let mut v=vec![88,51,17]; let first=v[0]; v.push(60); | Copy instead of reference. | Rust |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
process | process() | Add parentheses. | Swift |
System.out.println('result') | System.out.println('result'); | Add semicolon. | Java |
if num = 31 | if num == 31 | Use ==. | Ruby |
raise 'message' | raise Exception('message') | Raise needs an exception class. | Python |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
let index = 11; | let index = 11; | Correct. | JavaScript |
.Person {{ color: red; }} | .Person {{ color: red; }} | Correct. | CSS |
<ul><li>data<li>data</ul> | <ul><li>data</li><li>data</li></ul> | Close li. | HTML |
print('message') | print('message') | Correct. | R |
fn compute() -> i32 {{ 80 }} | fn compute() -> i32 {{ 80 }} | Correct. | Rust |
let vec=vec![13,97,9]; let first=&vec[0]; vec.push(39); | let mut vec=vec![13,97,9]; let first=vec[0]; vec.push(39); | Copy instead of reference. | Rust |
$z = 1; if ($z = 1) {{}} | $z = 1; if ($z == 1) {{}} | Use ==. | PHP |
function foo(): void {{ return 99; }} | function foo(): number {{ return 99; }} | Return type mismatch. | TypeScript |
function compute() {{ echo 'message'; }} | function compute() {{ echo 'message'; }} | Correct. | PHP |
<table><tr><td>test<td>test</tr></table> | <table><tr><td>test</td><td>test</td></tr></table> | Close td. | HTML |
else
print('result') | else:
print('result') | Colon after else. | Python |
echo 'value' | echo 'value'; | Add semicolon. | PHP |
SELECT name email FROM orders; | SELECT name, email FROM orders; | Add comma. | SQL |
if x > 85
puts 'data' | if x > 85
puts 'data'
end | Add 'end'. | Ruby |
$items[81] | if ($items.Count -gt 81) {{ $items[81] }} | Check bounds. | PowerShell |
<p>value <b>world</p></b> | <p>value <b>world</b></p> | Nest properly. | HTML |
p {{ color: red }} | p {{ color: red; }} | Add semicolon. | CSS |
x := 56 | x := 56 | Correct. | Go |
function process(item:string){{return item;}} process(65); | function process(item:string){{return item;}} process('result'); | Pass correct type. | TypeScript |
let result: number | null = null; result.toFixed(65); | let result: number | null = null; if(result!==null) result.toFixed(65); | Null check. | TypeScript |
items(44) | if length(items) >= 44, items(44), end | Check length. | MATLAB |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
1num = 10 | num1 = 10 | Variable cannot start with digit. | Python |
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