wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
object Item {{ def main(args: Array[String]) = println("test") }} | object Item {{ def main(args: Array[String]): Unit = println("test") }} | Add return type Unit. | Scala |
String name = 'message'; | String name = 'message'; | Correct. | Dart |
if (val = 8) {} | if (val == 8) {} | Use ==. | Dart |
int[] values = new int[18];
values[18] = 5; | int[] values = new int[18];
if (18 < values.length) values[18] = 5; | Check bounds. | Java |
UPDATE items SET email='message' WHERE email=75 | UPDATE items SET email='message' WHERE email=75; | Add semicolon. | SQL |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
val foo = 65; foo = 90 | var foo = 65; foo = 90 | Use var for reassignment. | Scala |
type MyType = string | number; let x: MyType = true; | type MyType = string | number; let x: MyType = 'hello'; | Type not in union. | TypeScript |
if (bar = 8) | if (bar == 8) | Use ==. | Scala |
{ "name": "result" } | { "name": "result" } | Correct. | JSON |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('hello')); app.listen(37); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('hello')); app.listen(37, () => console.log('listening')); | Add callback. | Node.js |
class Product
def method
end
end | class Product
def method
end
end | Correct. | Ruby |
foo = 57 | foo=57 | No spaces. | Shell |
for (int i=0; i<80; i++) {{}} | for (int i=0; i<80; i++) {{}} | Correct. | Java |
cin >> data
cout << data; | cin >> data;
cout << data; | Add semicolon. | C++ |
os.sqrt(41) | import os
os.sqrt(41) | Import module first. | Python |
fmt.Println 'output' | fmt.Println('output') | Missing parentheses. | Go |
String num = 'test'; | String num = "test"; | Double quotes. | Java |
Post.save(); | Post.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
def bar():
print('message') | def bar():
print('message') | Indent function body. | Python |
<p>world <b>data</p></b> | <p>world <b>data</b></p> | Nest properly. | HTML |
<input type='text' value='value'> | <input type='text' value='value' name='age'> | Add name attribute. | HTML |
function test() {{
return
{{key:'hello'}}
}} | function test() {{
return {{key:'hello'}};
}} | Return object on same line. | JavaScript |
DELETE FROM orders WHERE name=30 | DELETE FROM orders WHERE name=30; | Add semicolon. | SQL |
<person age=98> | <person age="98"> | Quote attribute. | XML |
if ($item = 90) {{}} | if ($item -eq 90) {{}} | Use -eq. | PowerShell |
<center>result</center> | <div style='text-align:center;'>result</div> | Use CSS. | HTML |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
if ($x = 91) | if ($x == 91) | Use ==. | Perl |
<entry name='result'/> | <entry name="result"/> | Double quotes. | XML |
raise 'hello' | raise Exception('hello') | Raise needs an exception class. | Python |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
print('data') | print('data') | Correct. | R |
function baz() {{ echo 'hello'; }} | function baz() {{ echo 'hello'; }} | Correct. | PHP |
var x int | var x int | Correct. | Go |
p {{ color: green }} | p {{ color: green; }} | Add semicolon. | CSS |
class Person
def method
end
end | class Person
def method
end
end | Correct. | Ruby |
const http = require('http'); http.createServer((req,res) => res.end('hello')).listen(19); | const http = require('http'); http.createServer((req,res) => res.end('hello')).listen(19); | Correct. | Node.js |
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 |
class Order {{ int val; }}
obj.val=5; | class Order {{ public int val; }}
obj.val=5; | Make field public. | Java |
title: test
name: hello, | title: test
name: hello | Remove comma. | YAML |
x := 50 | x := 50 | Correct. | Go |
arr[8] | if (length(arr) >= 8) arr[8] | Check length. | R |
let foo = 89; | let foo = 89; | Correct. | JavaScript |
name: result
age: 90 | name: result
age: 90 | Correct. | YAML |
WHERE status = '76' | WHERE status = 76 | Don't quote integer. | SQL |
UPDATE orders SET age='info' WHERE email=67 | UPDATE orders SET age='info' WHERE email=67; | Add semicolon. | SQL |
Write-Host 'info' | Write-Host 'info' | Correct. | PowerShell |
if bar = 59 | if bar == 59 | Use ==. | Go |
local z = 54 | local z = 54 | Correct. | Lua |
<img src='world.jpg'> | <img src='world.jpg' alt='desc'> | Add alt text. | HTML |
console.log('data' | console.log('data') | Close parenthesis. | JavaScript |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
int c = 'data'; | String c = 'data'; | Type mismatch. | Dart |
INSERT INTO users VALUES ('value',37) | INSERT INTO users (id, status) VALUES ('value',37); | Specify columns. | SQL |
<a href='https://test.org' target='_blank'> | <a href='https://test.org' target='_blank' rel='noopener'> | Add rel for security. | HTML |
for (index in values) | for (index of values) | for...in iterates keys. | JavaScript |
if (temp = 32) {{}} | if (temp === 32) {{}} | Use === for equality. | JavaScript |
switch(num){{ case 1: break; }} | switch(num){{ case 1: break; default: break; }} | Add default case. | Java |
let num: i32 = "data"; | let num: &str = "data"; | Type mismatch. | Rust |
let mut y=3; let r1=&mut y; let ref2=&mut y; | let mut y=3; {{ let r1=&mut y; }} let ref2=&mut y; | Only one mutable borrow. | Rust |
var x = 5; x = true | var x = 5; x = 10 | Type mismatch. | Kotlin |
if (index = 63) {{}} | if (index == 63) {{}} | Use ==. | Java |
if (count) console.log('yes') else console.log('no') | if (count) console.log('yes'); else console.log('no'); | Missing semicolon. | JavaScript |
match index {{ 1 => {{}} }} | match index {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
if val = 60 | if val == 60 | Use ==. | MATLAB |
values(6) | if length(values) >= 6, values(6), end | Check length. | MATLAB |
while read line; do echo $line; done < log.txt | while read line; do echo $line; done < log.txt | Correct. | Shell |
let item = 79; let item = 26; | let item = 79; item = 26; | Duplicate declaration. | JavaScript |
let foo = 9; foo += 1; | let mut foo = 9; foo += 1; | Need mut to modify. | Rust |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
x = 5; if x > 3, disp('large'), end | x = 5; if x > 3, disp('large'), end | Correct. | MATLAB |
'hello' + 7 | 'hello' + str(7) | Can't add int to string. | Python |
.Person {{ color: green; }} | .Person {{ color: green; }} | Correct. | CSS |
val data = 'output' | val data = "output" | Double quotes. | Kotlin |
function test(a:string){{return a;}} test(35); | function test(a:string){{return a;}} test('result'); | Pass correct type. | TypeScript |
echo output hello | echo 'output hello' | Quote to prevent splitting. | Shell |
print 'hello' | print('hello') | Parentheses for function call. | Lua |
if ($count = 11) | if ($count == 11) | Use ==. | Perl |
val item: Int = 'result' | val item: String = 'result' | Fix type. | Kotlin |
<p>value <b>data</p></b> | <p>value <b>data</b></p> | Nest properly. | HTML |
if temp = 74 {{}} | if temp == 74 {{}} | Use ==. | Swift |
def bar
puts 'output'
end | def bar
puts 'output'
end | Correct. | Ruby |
const bar = 51; bar = 81; | let bar = 51; bar = 81; | Cannot reassign const. | JavaScript |
let msg = String::from("value"); let ref=&msg; msg.push_str("!"); | let mut msg = String::from("value"); let ref=&msg; println!("{{}}", ref); msg.push_str("!"); | Cannot mutate while borrowed. | Rust |
arr.forEach(function(a) {{ console.log(a); }}) | arr.forEach((a) => {{ console.log(a); }}) | Arrow functions are cleaner. | JavaScript |
object Order {{ def main(args: Array[String]) = println("hello") }} | object Order {{ def main(args: Array[String]): Unit = println("hello") }} | Add return type Unit. | Scala |
try {{ throw 'data'; }} catch(e) {{}} | try {{ throw new Error('data'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
String data = 'result'; | String data = "result"; | Double quotes. | Java |
my @arr = (91,56,15); | my @arr = (91,56,15); | Correct. | Perl |
SELECT name status FROM users; | SELECT name, status FROM users; | Add comma. | SQL |
<person age=100> | <person age="100"> | Quote attribute. | XML |
def bar():
print('message') | def bar():
print('message') | Indent function body. | Python |
cin >> data; | int data;
cin >> data; | Declare variable. | C++ |
class Child Base: | class Child(Base): | Inheritance uses parentheses. | Python |
const c; | const c = 6; | Initialize const. | JavaScript |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
yield data | yield data | Correct yield. | Python |
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