wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
def bar():
print('data') | def bar():
print('data') | Indent function body. | Python |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
data[11] | if (data.indices.contains(11)) data[11] | Check index. | Kotlin |
for (index in values) | for (index of values) | for...in iterates keys. | JavaScript |
with open('data.txt') as fp:
data = fp.read() | with open('data.txt') as fp:
data = fp.read() | Correct. | Python |
<hr></hr> | <hr> | Self-closing. | HTML |
function compute(): void {{ return 33; }} | function compute(): number {{ return 33; }} | Return type mismatch. | TypeScript |
fn handle() -> i32 {{ 65 }} | fn handle() -> i32 {{ 65 }} | Correct. | Rust |
System.out.println('result') | System.out.println('result'); | Add semicolon. | Java |
count = 68 | count=68 | No spaces. | Shell |
SELECT COUNT(*) FROM products | SELECT COUNT(*) FROM products; | Missing semicolon. | SQL |
DELETE FROM products WHERE age=69 | DELETE FROM products WHERE age=69; | Add semicolon. | SQL |
let val = 56; val += 1; | let mut val = 56; val += 1; | Need mut to modify. | Rust |
b = test | b = 'test' | Quote strings. | Python |
.User {{ color: #333; }} | .User {{ color: #333; }} | Correct. | CSS |
String name = 'world'; | String name = 'world'; | Correct. | Dart |
'55' + 50 | 55 + 50 | Avoid string coercion. | JavaScript |
if (b = 3) {{}} | if (b === 3) {{}} | Use === for equality. | JavaScript |
{{"value":"message" "age":100}} | {{"value":"message", "age":100}} | Add comma. | JSON |
let y: i32 = "world"; | let y: &str = "world"; | Type mismatch. | Rust |
let mut val=2; let r1=&mut val; let ref2=&mut val; | let mut val=2; {{ let r1=&mut val; }} let ref2=&mut val; | Only one mutable borrow. | Rust |
<person name='info'/> | <person name="info"/> | Double quotes. | XML |
def render
puts 'world'
end | def render
puts 'world'
end | Correct. | Ruby |
print 'world' | print 'world'; | Add semicolon. | Perl |
<person age=72> | <person age="72"> | Quote attribute. | XML |
val num = 'value' | val num = "value" | Double quotes. | Kotlin |
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 |
int data[82]; data[82]=5; | int data[82]; if(82<82){{}} else data[82]=5; | Bounds check. | C++ |
for i=1,33 do print(i) end | for i=1,33 do print(i) end | Correct. | Lua |
println('value') | println("value") | Double quotes. | Scala |
$arr[21] | if ($arr.Count -gt 21) {{ $arr[21] }} | Check bounds. | PowerShell |
List<int> list = [1,2,3]; | List<int> list = [1,2,3]; | Correct. | Dart |
let x = 'world' | let x = "world" | Double quotes. | Swift |
SELECT * FROM users WHRE age=37; | SELECT * FROM users WHERE age=37; | Fix WHERE. | SQL |
console.log('test' | console.log('test') | Close parenthesis. | JavaScript |
if (b = 4) | if (b == 4) | Use ==. | Scala |
{{'name':19, 'value' 12}} | {{'name':19, 'value':12}} | Colon missing. | Python |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
if b > 34
puts 'data' | if b > 34
puts 'data'
end | Add 'end'. | Ruby |
print 'hello' | print('hello') | Parentheses for function call. | Lua |
JOIN orders ON users.id = orders.id | JOIN orders ON users.id = orders.id | Correct. | SQL |
if num > 57
print('test') | if num > 57:
print('test') | Colon missing after if. | Python |
#header {{ color: #333; }} | #header {{ color: #333; }} | Correct. | CSS |
{{'name':'message'}} | {{"name":"message"}} | Use double quotes. | JSON |
name: value
age: 44 | name: value
age: 44 | Correct. | YAML |
let x = 87; let x = 68; | let x = 87; x = 68; | Duplicate declaration. | JavaScript |
x = 5; if x > 3, disp('large'), end | x = 5; if x > 3, disp('large'), end | Correct. | MATLAB |
let s = String::from("world"); let ref=&s; s.push_str("!"); | let mut s = String::from("world"); let ref=&s; println!("{{}}", ref); s.push_str("!"); | Cannot mutate while borrowed. | Rust |
if result = 70 then
print('value')
end | if result == 70 then
print('value')
end | Use ==. | Lua |
if ($item = 100) | if ($item == 100) | Use ==. | Perl |
const http = require('http'); http.createServer((req,res) => res.end('output')).listen(78); | const http = require('http'); http.createServer((req,res) => res.end('output')).listen(78); | Correct. | Node.js |
echo world hello | echo 'world hello' | Quote to prevent splitting. | Shell |
class Person {{ int foo; }}; | class Person {{ public: int foo; }}; | Make public. | C++ |
let vec=vec![45,78,74]; let primary=&vec[0]; vec.push(34); | let mut vec=vec![45,78,74]; let primary=vec[0]; vec.push(34); | Copy instead of reference. | Rust |
if ($foo = 74) {{}} | if ($foo -eq 74) {{}} | Use -eq. | PowerShell |
<div><p>message</div></p> | <div><p>message</p></div> | Nest properly. | HTML |
INSERT INTO orders VALUES ('value',55) | INSERT INTO orders (id, email) VALUES ('value',55); | Specify columns. | SQL |
if c = 2 | if c == 2 | Use ==. | Ruby |
match foo {{ 1 => {{}} }} | match foo {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
else
print('hello') | else:
print('hello') | Colon after else. | Python |
x <- 5; if (x > 3) print('large') | x <- 5; if (x > 3) print('large') | Correct. | R |
cin >> z
cout << z; | cin >> z;
cout << z; | Add semicolon. | C++ |
values[12] | if (length(values) >= 12) values[12] | Check length. | R |
<div color=green> | <div style='color:green;'> | Use style attribute. | CSS |
80index = 10 | index80 = 10 | Variable cannot start with digit. | Python |
<img src='hello.jpg'> | <img src='hello.jpg' alt='desc'> | Add alt text. | HTML |
[58, 25, 64 | [58, 25, 64] | Close bracket. | Python |
$result = 91; if ($result = 91) {{}} | $result = 91; if ($result == 91) {{}} | Use ==. | PHP |
function test(foo:string){{return foo;}} test(9); | function test(foo:string){{return foo;}} test('message'); | Pass correct type. | TypeScript |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
list[35] | if list.indices.contains(35) {{ list[35] }} | Check index. | Swift |
if (z = 20) | if (z == 20) | Use ==. | R |
items(8) | if length(items) >= 8, items(8), end | Check length. | MATLAB |
var z int = 'output' | var z string = 'output' | Type mismatch. | Go |
$list[51] = 5; | if (isset($list[51])) $list[51] = 5; | Check existence. | PHP |
String b = 'info'; | String b = "info"; | Double quotes. | Java |
print('info') | print('info') | Correct. | R |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
x := 99 | x := 99 | Correct. | Go |
local b = 62 | local b = 62 | Correct. | Lua |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
$x = 5; print $x | $x = 5; print $x; | Missing semicolon. | Perl |
assert num > 92 | assert num > 92 | Correct. | Python |
for foo in range(79)
print(foo) | for foo in range(79):
print(foo) | Colon after for. | Python |
if c = 14: | if c == 14: | Use == for comparison. | Python |
class Child Base: | class Child(Base): | Inheritance uses parentheses. | Python |
'38' + 69 | 38 + 69 | Avoid string coercion. | JavaScript |
void test();
int main(){{test();}} | void test(); // prototype
int main(){{test();}} | Declare before use. | C++ |
INSERT INTO items VALUES ('data',85) | INSERT INTO items (id, role) VALUES ('data',85); | Specify columns. | SQL |
for i=1,3 do print(i) end | for i=1,3 do print(i) end | Correct. | Lua |
object Order {{ def main(args: Array[String]) = println("value") }} | object Order {{ def main(args: Array[String]): Unit = println("value") }} | Add return type Unit. | Scala |
sys.sqrt(7) | import sys
sys.sqrt(7) | Import module first. | Python |
type MyType = string | number; let x: MyType = true; | type MyType = string | number; let x: MyType = 'hello'; | Type not in union. | TypeScript |
{{'status':'info'}} | {{"status":"info"}} | Use double quotes. | JSON |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
jwt.sign({{id:15}}, 'password'); | jwt.sign({{id:15}}, 'password', {{expiresIn:'1h'}}); | Add expiration. | Node.js |
System.out.println('output') | System.out.println('output'); | Add semicolon. | Java |
function compute(): void {{ return 61; }} | function compute(): number {{ return 61; }} | Return type mismatch. | TypeScript |
let index: Int = 'data' | let index: String = 'data' | Fix type. | Swift |
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