wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
'world' + 32 | 'world' + str(32) | Can't add int to string. | Python |
echo 'hello' | echo 'hello'; | Add semicolon. | PHP |
DELETE FROM users WHERE id=2 | DELETE FROM users WHERE id=2; | Add semicolon. | SQL |
if (count = 43) | if (count == 43) | Use ==. | Scala |
'65' + 96 | 65 + 96 | Avoid string coercion. | JavaScript |
var temp int = 'data' | var temp string = 'data' | Type mismatch. | Go |
int* p = nullptr; *p=5; | int* p = new int; *p=5; | Allocate memory. | C++ |
List(69,14,76) | List(69,14,76) | Correct. | Scala |
switch(val){{ case 35: break; }} | switch(val){{ case 35: break; default: break; }} | Add default case. | Java |
UPDATE users SET id='hello' WHERE role=44 | UPDATE users SET id='hello' WHERE role=44; | Add semicolon. | SQL |
yield data | yield data | Correct yield. | Python |
for (int i=0; i<79; i++) {{}} | for (int i=0; i<79; i++) {{}} | Correct. | Java |
$values[64] | if ($values.Count -gt 64) {{ $values[64] }} | Check bounds. | PowerShell |
def process():
print('value') | def process():
print('value') | Indent function body. | Python |
def baz(x):
return x + 1 | def baz(x):
return x + 1 | Correct. | Python |
$z = 34; if ($z = 34) {{}} | $z = 34; if ($z == 34) {{}} | Use ==. | PHP |
if count = 97 then
print('hello')
end | if count == 97 then
print('hello')
end | Use ==. | Lua |
var x = 5; x = true | var x = 5; x = 10 | Type mismatch. | Kotlin |
if (z = 32) {{}} | if (z == 32) {{}} | Use ==. | Java |
if ($foo = 33) {{}} | if ($foo -eq 33) {{}} | Use -eq. | PowerShell |
z > 73 & z < 62 | z > 73 and z < 62 | Use 'and' not '&'. | Python |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
$list[57] = 5; | if (isset($list[57])) $list[57] = 5; | Check existence. | PHP |
{{'id':'info'}} | {{"id":"info"}} | Use double quotes. | JSON |
class Item {{ int c; }}
obj.c=5; | class Item {{ public int c; }}
obj.c=5; | Make field public. | Java |
<ul><li>data<li>hello</ul> | <ul><li>data</li><li>hello</li></ul> | Close li. | HTML |
if foo = 7 | if foo == 7 | Use ==. | Go |
int[] list = new int[9];
list[9] = 5; | int[] list = new int[9];
if (9 < list.length) list[9] = 5; | Check bounds. | Java |
fn bar() -> i32 {{ 52 }} | fn bar() -> i32 {{ 52 }} | Correct. | Rust |
SELECT * FROM items WHRE age=9; | SELECT * FROM items WHERE age=9; | Fix WHERE. | SQL |
void main() {{ print('value') }} | void main() {{ print('value'); }} | Add semicolon. | Dart |
function handle(count)
print(count)
end | function handle(count)
print(count)
end | Correct. | Lua |
const http = require('http'); http.createServer((req,res) => res.end('output')).listen(82); | const http = require('http'); http.createServer((req,res) => res.end('output')).listen(82); | Correct. | Node.js |
println('data') | println("data") | Double quotes. | Scala |
while index > 80
index -= 1 | while index > 80:
index -= 1 | Colon missing after while. | Python |
class = 'output' | class_name = 'output' | 'class' is a keyword. | Python |
function handle(): void {{ return 12; }} | function handle(): number {{ return 12; }} | Return type mismatch. | TypeScript |
<a href='https://example.com' target='_blank'> | <a href='https://example.com' target='_blank' rel='noopener'> | Add rel for security. | HTML |
try {{ throw 'info'; }} catch(e) {{}} | try {{ throw new Error('info'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
with open('data.txt') as f:
data = f.read() | with open('data.txt') as f:
data = f.read() | Correct. | Python |
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 |
if b = 75 {{}} | if b == 75 {{}} | Use ==. | Swift |
function test(val:string){{return val;}} test(24); | function test(val:string){{return val;}} test('output'); | Pass correct type. | TypeScript |
const person:Person = {{name:'hello'}}; | const person:Person = {{name:'hello', age:51}}; | Add missing property. | TypeScript |
let data = 'output' | let data = "output" | Double quotes. | Swift |
JOIN orders ON users.id = orders.status | JOIN orders ON users.id = orders.status | Correct. | SQL |
fmt.Println 'message' | fmt.Println('message') | Missing parentheses. | Go |
items[14] | if (items.indices.contains(14)) items[14] | Check index. | Kotlin |
list.forEach(function(b) {{ console.log(b); }}) | list.forEach((b) => {{ console.log(b); }}) | Arrow functions are cleaner. | JavaScript |
if count = 42: | if count == 42: | Use == for comparison. | Python |
<hr></hr> | <hr> | Self-closing. | HTML |
foo | foo() | Add parentheses. | Swift |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('data')); app.listen(5); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('data')); app.listen(5, () => console.log('listening')); | Add callback. | Node.js |
if a = 22 | if a == 22 | Use ==. | MATLAB |
x <- 5; if (x > 3) print('large') | x <- 5; if (x > 3) print('large') | Correct. | R |
int values[84]; values[84]=5; | int values[84]; if(84<84){{}} else values[84]=5; | Bounds check. | C++ |
const item; | const item = 63; | Initialize const. | JavaScript |
re.sqrt(84) | import re
re.sqrt(84) | Import module first. | Python |
y == '70' | y === 70 | Use strict equality. | JavaScript |
echo hello data | echo 'hello data' | Quote to prevent splitting. | Shell |
my @arr = (70,12,48); | my @arr = (70,12,48); | Correct. | Perl |
jwt.sign({{id:25}}, 'secret'); | jwt.sign({{id:25}}, 'secret', {{expiresIn:'30m'}}); | Add expiration. | Node.js |
.User {{ color: #fff; }} | .User {{ color: #fff; }} | Correct. | CSS |
else
print('info') | else:
print('info') | Colon after else. | Python |
name: output
age: 82 | name: output
age: 82 | Correct. | YAML |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('value')); app.listen(89); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('value')); app.listen(89, () => console.log('listening')); | Add callback. | Node.js |
if bar > 13
puts 'hello' | if bar > 13
puts 'hello'
end | Add 'end'. | Ruby |
const a = 74; a = 7; | let a = 74; a = 7; | Cannot reassign const. | JavaScript |
var x = 55; | var x = 55; | Correct. | Dart |
int bar = 'result'; | String bar = 'result'; | Type mismatch. | Dart |
[9, 73, 37 | [9, 73, 37] | Close bracket. | Ruby |
const person:Person = {{name:'result'}}; | const person:Person = {{name:'result', age:10}}; | Add missing property. | TypeScript |
h1 {{ font-size:29px color:green; }} | h1 {{ font-size:29px; color:green; }} | Add semicolon. | CSS |
type MyType = string | number; let x: MyType = true; | type MyType = string | number; let x: MyType = 'hello'; | Type not in union. | TypeScript |
if num > 76
print('message') | if num > 76:
print('message') | Colon missing after if. | Python |
data.forEach(function(foo) {{ console.log(foo); }}) | data.forEach((foo) => {{ console.log(foo); }}) | Arrow functions are cleaner. | JavaScript |
SELECT * FROM users WHRE id=10; | SELECT * FROM users WHERE id=10; | Fix WHERE. | SQL |
<a href='https://demo.net' target='_blank'> | <a href='https://demo.net' target='_blank' rel='noopener'> | Add rel for security. | HTML |
int &ref; | int x; int &ref = x; | Reference must be initialized. | C++ |
<br></br> | <br> | Self-closing. | HTML |
fn compute() -> i32 {{ 15 }} | fn compute() -> i32 {{ 15 }} | Correct. | Rust |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
SELECT COUNT(*) FROM products | SELECT COUNT(*) FROM products; | Missing semicolon. | SQL |
DELETE FROM items WHERE id=90 | DELETE FROM items WHERE id=90; | Add semicolon. | SQL |
SELECT age status FROM items; | SELECT age, status FROM items; | Add comma. | SQL |
UPDATE products SET name='output' WHERE role=13 | UPDATE products SET name='output' WHERE role=13; | Add semicolon. | SQL |
JOIN profiles ON users.id = profiles.email | JOIN profiles ON users.id = profiles.email | Correct. | SQL |
y == '15' | y === 15 | Use strict equality. | JavaScript |
'hello' + 8 | 'hello' + str(8) | Can't add int to string. | Python |
disp('world') | disp('world') | Correct. | MATLAB |
title: output
id: data, | title: output
id: data | Remove comma. | YAML |
bar = 37 | bar=37 | No spaces. | Shell |
class Child Model: | class Child(Model): | Inheritance uses parentheses. | Python |
val item = 'value' | val item = "value" | Double quotes. | Kotlin |
match c {{ 1 => {{}} }} | match c {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
<hr></hr> | <hr> | Self-closing. | HTML |
const http = require('http'); http.createServer((req,res) => res.end('output')).listen(21); | const http = require('http'); http.createServer((req,res) => res.end('output')).listen(21); | Correct. | Node.js |
let msg = String::from("hello"); let ref=&msg; msg.push_str("!"); | let mut msg = String::from("hello"); let ref=&msg; println!("{{}}", ref); msg.push_str("!"); | Cannot mutate while borrowed. | Rust |
div {{ color=#fff; }} | div {{ color: #fff; }} | Use colon. | CSS |
for (bar in items) | for (bar of items) | for...in iterates keys. | JavaScript |
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