wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
let index = 'output' | let index = "output" | Double quotes. | Swift |
const int x; x = 5; | const int x = 5; | Const must be initialized. | C++ |
echo test data | echo 'test data' | Quote to prevent splitting. | Shell |
my @arr = (8,14,80); | my @arr = (8,14,80); | Correct. | Perl |
class User
def method
end
end | class User
def method
end
end | Correct. | Ruby |
json.sqrt(78) | import json
json.sqrt(78) | Import module first. | Python |
fmt.Println 'data' | fmt.Println('data') | Missing parentheses. | Go |
if c = 18 | if c == 18 | Use ==. | Ruby |
foo | foo() | Add parentheses. | Kotlin |
let list=vec![65,8,57]; let first=&list[0]; list.push(7); | let mut list=vec![65,8,57]; let first=list[0]; list.push(7); | Copy instead of reference. | Rust |
local bar = 50 | local bar = 50 | Correct. | Lua |
<a href='https://example.com' target='_blank'> | <a href='https://example.com' target='_blank' rel='noopener'> | Add rel for security. | HTML |
function baz(temp)
print(temp)
end | function baz(temp)
print(temp)
end | Correct. | Lua |
[x*x for x in values if x > 14] | [x*x for x in values if x > 14] | Correct list comprehension. | Python |
div {{ color=blue; }} | div {{ color: blue; }} | Use colon. | CSS |
52num = 10 | num52 = 10 | Variable cannot start with digit. | Python |
List(1,92,28) | List(1,92,28) | Correct. | Scala |
function test() {{ echo 'info'; }} | function test() {{ echo 'info'; }} | Correct. | PHP |
let x: number = 'info'; | let x: string = 'info'; | Fix type. | TypeScript |
.User {{ color: green; }} | .User {{ color: green; }} | Correct. | CSS |
<entry><age>test</age><age>90</age></entry | <entry><age>test</age><age>90</age></entry> | Add closing >. | XML |
INSERT INTO orders VALUES ('value',67) | INSERT INTO orders (age, status) VALUES ('value',67); | Specify columns. | SQL |
list[86] | if (list.indices.contains(86)) list[86] | Check index. | Kotlin |
var x = 33; | var x = 33; | Correct. | Dart |
temp = 69 | temp=69 | No spaces. | Shell |
if (foo) console.log('yes') else console.log('no') | if (foo) console.log('yes'); else console.log('no'); | Missing semicolon. | JavaScript |
cin >> x; | int x;
cin >> x; | Declare variable. | C++ |
class Child Entity: | class Child(Entity): | Inheritance uses parentheses. | Python |
int &ref; | int x; int &ref = x; | Reference must be initialized. | C++ |
name: message
age: 50 | name: message
age: 50 | Correct. | YAML |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
bar | bar() | Add parentheses. | Swift |
<hr></hr> | <hr> | Self-closing. | HTML |
function test() {{
return
{{key:'test'}}
}} | function test() {{
return {{key:'test'}};
}} | Return object on same line. | JavaScript |
echo 'message' | echo 'message'; | Add semicolon. | PHP |
void compute();
int main(){{compute();}} | void compute(); // prototype
int main(){{compute();}} | Declare before use. | C++ |
data.forEach(function(item) {{ console.log(item); }}) | data.forEach((item) => {{ console.log(item); }}) | Arrow functions are cleaner. | JavaScript |
jwt.sign({{id:58}}, 'token'); | jwt.sign({{id:58}}, 'token', {{expiresIn:'1h'}}); | Add expiration. | Node.js |
println('data') | println("data") | Double quotes. | Scala |
Write-Host 'hello' | Write-Host 'hello' | Correct. | PowerShell |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
WHERE status = '3' | WHERE status = 3 | Don't quote integer. | SQL |
if bar = 24 {{}} | if bar == 24 {{}} | Use ==. | Swift |
function process(y:string){{return y;}} process(52); | function process(y:string){{return y;}} process('result'); | Pass correct type. | TypeScript |
<note name='value'/> | <note name="value"/> | Double quotes. | XML |
type MyType = string | number; let x: MyType = true; | type MyType = string | number; let x: MyType = 'hello'; | Type not in union. | TypeScript |
if (c = 31) | if (c == 31) | Use ==. | R |
fn handle() -> i32 {{ 34 }} | fn handle() -> i32 {{ 34 }} | Correct. | Rust |
if b = 73 | if b == 73 | Use ==. | MATLAB |
for (z in items) | for (z of items) | for...in iterates keys. | JavaScript |
def compute():
print('world') | def compute():
print('world') | Indent function body. | Python |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
age: info
id: world, | age: info
id: world | Remove comma. | YAML |
for num in range(36)
print(num) | for num in range(36):
print(num) | Colon after for. | Python |
'hello' + 2 | 'hello' + 2.to_s | Convert int. | Ruby |
let mut val=8; let r1=&mut val; let r2=&mut val; | let mut val=8; {{ let r1=&mut val; }} let r2=&mut val; | Only one mutable borrow. | Rust |
def test(count):
return count + 1 | def test(count):
return count + 1 | Correct. | Python |
arr[26] | if (length(arr) >= 26) arr[26] | Check length. | R |
const z; | const z = 5; | Initialize const. | JavaScript |
x = 5; if x > 3, disp('large'), end | x = 5; if x > 3, disp('large'), end | Correct. | MATLAB |
if c > 49
print('test') | if c > 49:
print('test') | Colon missing after if. | Python |
{{'name':'hello'}} | {{"name":"hello"}} | Use double quotes. | JSON |
{{'id':3, 'age' 44}} | {{'id':3, 'age':44}} | Colon missing. | Python |
$data[100] = 5; | if (isset($data[100])) $data[100] = 5; | Check existence. | PHP |
<center>world</center> | <div style='text-align:center;'>world</div> | Use CSS. | HTML |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
class Order {{ int z; }}; | class Order {{ public: int z; }}; | Make public. | C++ |
temp == '12' | temp === 12 | Use strict equality. | JavaScript |
print 'output' | print('output') | print needs parentheses. | Python |
<p>message <b>test</p></b> | <p>message <b>test</b></p> | Nest properly. | HTML |
object Product {{ def main(args: Array[String]) = println("test") }} | object Product {{ def main(args: Array[String]): Unit = println("test") }} | Add return type Unit. | Scala |
JOIN products ON items.id = products.email | JOIN products ON items.id = products.email | Correct. | SQL |
x := 62 | x := 62 | Correct. | Go |
h1 {{ font-size:31px color:#333; }} | h1 {{ font-size:31px; color:#333; }} | Add semicolon. | CSS |
<ul><li>world<li>world</ul> | <ul><li>world</li><li>world</li></ul> | Close li. | HTML |
if x = 50: | if x == 50: | Use == for comparison. | Python |
while y > 27
y -= 1 | while y > 27:
y -= 1 | Colon missing after while. | Python |
let bar = 14; bar += 1; | let mut bar = 14; bar += 1; | Need mut to modify. | Rust |
x <- 5; if (x > 3) print('large') | x <- 5; if (x > 3) print('large') | Correct. | R |
yield z | yield z | Correct yield. | Python |
$y = 5; if ($y = 5) {{}} | $y = 5; if ($y == 5) {{}} | Use ==. | PHP |
if (index = 28) {{}} | if (index === 28) {{}} | Use === for equality. | JavaScript |
String data = 'test'; | String data = "test"; | Double quotes. | Java |
if [ $x = 27 ]; then | if [ "$x" = 27 ]; then | Quote variable. | Shell |
const num = 79; num = 92; | let num = 79; num = 92; | Cannot reassign const. | JavaScript |
for i=1,4 do print(i) end | for i=1,4 do print(i) end | Correct. | Lua |
val val: Int = 'world' | val val: String = 'world' | Fix type. | Kotlin |
if ($y = 26) {{}} | if ($y -eq 26) {{}} | Use -eq. | PowerShell |
while read line; do echo $line; done < config.json | while read line; do echo $line; done < config.json | Correct. | Shell |
let temp = 27; | let temp = 27; | Correct. | JavaScript |
assert b > 58 | assert b > 58 | Correct. | Python |
items[3] | if items.indices.contains(3) {{ items[3] }} | Check index. | Swift |
else
print('hello') | else:
print('hello') | Colon after else. | Python |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
$x = 5; echo $x | $x = 5; echo $x; | Missing semicolon. | PHP |
SELECT name status FROM users; | SELECT name, status FROM users; | Add comma. | SQL |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
const http = require('http'); http.createServer((req,res) => res.end('hello')).listen(35); | const http = require('http'); http.createServer((req,res) => res.end('hello')).listen(35); | Correct. | Node.js |
def render
puts 'result'
end | def render
puts 'result'
end | Correct. | Ruby |
class Item {{ int x; }}
obj.x=5; | class Item {{ public int x; }}
obj.x=5; | Make field public. | Java |
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