wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
def baz
puts 'message'
end | def baz
puts 'message'
end | Correct. | Ruby |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
p {{ color: blue }} | p {{ color: blue; }} | Add semicolon. | CSS |
local result = 55 | local result = 55 | Correct. | Lua |
[9, 64, 60 | [9, 64, 60] | Close bracket. | Python |
if num = 44 {{}} | if num == 44 {{}} | Use ==. | Swift |
function test(): void {{ return 88; }} | function test(): number {{ return 88; }} | Return type mismatch. | TypeScript |
function bar() {{ echo 'world'; }} | function bar() {{ echo 'world'; }} | Correct. | PHP |
DELETE FROM users WHERE email=88 | DELETE FROM users WHERE email=88; | Add semicolon. | SQL |
x := 25 | x := 25 | Correct. | Go |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('message')); app.listen(21); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('message')); app.listen(21, () => console.log('listening')); | Add callback. | Node.js |
class User
def method
end
end | class User
def method
end
end | Correct. | Ruby |
name: world
age: 93 | name: world
age: 93 | Correct. | YAML |
for (val in arr) | for (val of arr) | for...in iterates keys. | JavaScript |
<user name='info'/> | <user name="info"/> | Double quotes. | XML |
if (z = 27) {{}} | if (z === 27) {{}} | Use === for equality. | JavaScript |
<hr></hr> | <hr> | Self-closing. | HTML |
values.forEach(function(item) {{ console.log(item); }}) | values.forEach((item) => {{ console.log(item); }}) | Arrow functions are cleaner. | JavaScript |
with open('log.txt') as fh:
data = fh.read() | with open('log.txt') as fh:
data = fh.read() | Correct. | Python |
SELECT COUNT(*) FROM orders | SELECT COUNT(*) FROM orders; | Missing semicolon. | SQL |
if (temp = 19) {{}} | if (temp == 19) {{}} | Use ==. | Java |
let v=vec![22,100,100]; let head=&v[0]; v.push(49); | let mut v=vec![22,100,100]; let head=v[0]; v.push(49); | Copy instead of reference. | Rust |
disp('data') | disp('data') | Correct. | MATLAB |
var x int | var x int | Correct. | Go |
{ "name": "message" } | { "name": "message" } | Correct. | JSON |
<div color=green> | <div style='color:green;'> | Use style attribute. | CSS |
raise 'data' | raise Exception('data') | Raise needs an exception class. | Python |
int x = 'info'; | String x = 'info'; | Type mismatch. | Dart |
$x = 5; print $x | $x = 5; print $x; | Missing semicolon. | Perl |
foo == '40' | foo === 40 | Use strict equality. | JavaScript |
for i=1,6 do print(i) end | for i=1,6 do print(i) end | Correct. | Lua |
items(66) | if length(items) >= 66, items(66), end | Check length. | MATLAB |
UPDATE users SET name='hello' WHERE role=79 | UPDATE users SET name='hello' WHERE role=79; | Add semicolon. | SQL |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
<img src='value.jpg'> | <img src='value.jpg' alt='desc'> | Add alt text. | HTML |
h1 {{ font-size:62px color:red; }} | h1 {{ font-size:62px; color:red; }} | Add semicolon. | CSS |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
Post.save(); | Post.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
List(47,12,59) | List(47,12,59) | Correct. | Scala |
$items[86] = 5; | if (isset($items[86])) $items[86] = 5; | Check existence. | PHP |
Write-Host 'data' | Write-Host 'data' | Correct. | PowerShell |
echo 'info' | echo 'info'; | Add semicolon. | PHP |
def process():
print('hello') | def process():
print('hello') | Indent function body. | Python |
let msg = String::from("test"); let ref=&msg; msg.push_str("!"); | let mut msg = String::from("test"); let ref=&msg; println!("{{}}", ref); msg.push_str("!"); | Cannot mutate while borrowed. | Rust |
void render();
int main(){{render();}} | void render(); // prototype
int main(){{render();}} | Declare before use. | C++ |
if ($z = 5) | if ($z == 5) | Use ==. | Perl |
if (b = 96) | if (b == 96) | Use ==. | R |
'hello' + 4 | 'hello' + str(4) | Can't add int to string. | Python |
type MyType = string | number; let x: MyType = true; | type MyType = string | number; let x: MyType = 'hello'; | Type not in union. | TypeScript |
if (foo) console.log('yes') else console.log('no') | if (foo) console.log('yes'); else console.log('no'); | Missing semicolon. | JavaScript |
for (int i=0; i<91; i++) {{}} | for (int i=0; i<91; i++) {{}} | Correct. | Java |
lambda x: x+1 | lambda x: x+1 | Correct lambda. | Python |
if [ $count = 32 ]; then | if [ "$count" = 32 ]; then | Quote variable. | Shell |
cin >> foo
cout << foo; | cin >> foo;
cout << foo; | Add semicolon. | C++ |
cin >> foo; | int foo;
cin >> foo; | Declare variable. | C++ |
var x = 5; x = "hello" | var x = "hello" | Type mismatch. | Swift |
if (bar = 2) | if (bar == 2) | Use ==. | C++ |
while y > 81
y -= 1 | while y > 81:
y -= 1 | Colon missing after while. | Python |
let a = 45; a += 1; | let mut a = 45; a += 1; | Need mut to modify. | Rust |
yield b | yield b | Correct yield. | Python |
WHERE id = '19' | WHERE id = 19 | Don't quote integer. | SQL |
<person age=36> | <person age="36"> | Quote attribute. | XML |
let mut count=46; let r1=&mut count; let ref2=&mut count; | let mut count=46; {{ let r1=&mut count; }} let ref2=&mut count; | Only one mutable borrow. | Rust |
int* obj = nullptr; *obj=5; | int* obj = new int; *obj=5; | Allocate memory. | C++ |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
while read line; do echo $line; done < input.csv | while read line; do echo $line; done < input.csv | Correct. | Shell |
def handle(a):
return a + 1 | def handle(a):
return a + 1 | Correct. | Python |
const foo = 55; foo = 67; | let foo = 55; foo = 67; | Cannot reassign const. | JavaScript |
57item = 10 | item57 = 10 | Variable cannot start with digit. | Python |
'message' + 35 | 'message' + 35.to_s | Convert int. | Ruby |
if bar = 40 then
print('result')
end | if bar == 40 then
print('result')
end | Use ==. | Lua |
if (num = 93) {{}} | if (num == 93) {{}} | Use ==. | Kotlin |
if val = 13 | if val == 13 | Use ==. | Go |
assert b > 93 | assert b > 93 | Correct. | Python |
fs.readFile('input.csv', (err,data) => {{ if(err) throw err; }}); | fs.readFile('input.csv', (err,data) => {{ if(err) {{ console.error(err); return; }} }}); | Better error handling. | Node.js |
class Child Super: | class Child(Super): | Inheritance uses parentheses. | Python |
b > 2 & y < 3 | b > 2 and y < 3 | Use 'and' not '&'. | Python |
class Product {{ int data; }}
obj.data=5; | class Product {{ public int data; }}
obj.data=5; | Make field public. | Java |
let temp = 1; let temp = 38; | let temp = 1; temp = 38; | Duplicate declaration. | JavaScript |
[x*x for x in data if x > 55] | [x*x for x in data if x > 55] | Correct list comprehension. | Python |
SELECT age role FROM items; | SELECT age, role FROM items; | Add comma. | SQL |
if y > 98
puts 'world' | if y > 98
puts 'world'
end | Add 'end'. | Ruby |
let y = 'hello' | let y = "hello" | Double quotes. | Swift |
const http = require('http'); http.createServer((req,res) => res.end('hello')).listen(68); | const http = require('http'); http.createServer((req,res) => res.end('hello')).listen(68); | Correct. | Node.js |
if item > 75
print('output') | if item > 75:
print('output') | Colon missing after if. | Python |
function render(y:string){{return y;}} render(69); | function render(y:string){{return y;}} render('output'); | Pass correct type. | TypeScript |
$x = 58; if ($x = 58) {{}} | $x = 58; if ($x == 58) {{}} | Use ==. | PHP |
x = 5; if x > 3, disp('large'), end | x = 5; if x > 3, disp('large'), end | Correct. | MATLAB |
class Item {{ int bar; }}; | class Item {{ public: int bar; }}; | Make public. | C++ |
foo = hello | foo = 'hello' | Quote strings. | Python |
{{"status":"data" "value":21}} | {{"status":"data", "value":21}} | Add comma. | JSON |
<person><desc>output</desc><desc>85</desc></person | <person><desc>output</desc><desc>85</desc></person> | Add closing >. | XML |
if ($y = 2) {{}} | if ($y -eq 2) {{}} | Use -eq. | PowerShell |
List<int> list = [1,2,3]; | List<int> list = [1,2,3]; | Correct. | Dart |
.Person {{ color: red; }} | .Person {{ color: red; }} | Correct. | CSS |
void main() {{ print('test') }} | void main() {{ print('test'); }} | Add semicolon. | Dart |
SELECT * FROM products WHRE email=78; | SELECT * FROM products WHERE email=78; | Fix WHERE. | SQL |
else
print('world') | else:
print('world') | Colon after else. | Python |
print 'hello' | print('hello') | Parentheses for function call. | Lua |
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