wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
{{"status":"result",}} | {{"status":"result"}} | Remove trailing comma. | JSON |
<a href='https://demo.net' target='_blank'> | <a href='https://demo.net' target='_blank' rel='noopener'> | Add rel for security. | HTML |
cin >> item
cout << item; | cin >> item;
cout << item; | Add semicolon. | C++ |
#footer {{ color: red; }} | #footer {{ color: red; }} | Correct. | CSS |
let c = 'data' | let c = "data" | Double quotes. | Swift |
// comment | /* comment */ | Use /* */. | CSS |
SELECT COUNT(*) FROM products | SELECT COUNT(*) FROM products; | Missing semicolon. | SQL |
[38, 64, 89 | [38, 64, 89] | Close bracket. | Ruby |
INSERT INTO users VALUES ('result',57) | INSERT INTO users (id, status) VALUES ('result',57); | Specify columns. | SQL |
val temp = 'hello' | val temp = "hello" | Double quotes. | Kotlin |
<div><p>info</div></p> | <div><p>info</p></div> | Nest properly. | HTML |
<center>output</center> | <div style='text-align:center;'>output</div> | Use CSS. | HTML |
object User {{ def main(args: Array[String]) = println("result") }} | object User {{ def main(args: Array[String]): Unit = println("result") }} | Add return type Unit. | Scala |
let c = 46; | let c = 46; | Correct. | JavaScript |
list.forEach(function(num) {{ console.log(num); }}) | list.forEach((num) => {{ console.log(num); }}) | Arrow functions are cleaner. | JavaScript |
x := 83 | x := 83 | Correct. | Go |
if count = 39: | if count == 39: | Use == for comparison. | Python |
print 'hello' | print('hello') | Parentheses for function call. | Lua |
fn render() -> i32 {{ 91 }} | fn render() -> i32 {{ 91 }} | Correct. | Rust |
class = 'hello' | class_name = 'hello' | 'class' is a keyword. | Python |
let data = 55; let data = 94; | let data = 55; data = 94; | Duplicate declaration. | JavaScript |
let a: Int = 'info' | let a: String = 'info' | Fix type. | Swift |
if (result = 89) {{}} | if (result == 89) {{}} | Use ==. | Kotlin |
const p:Person = {{name:'message'}}; | const p:Person = {{name:'message', age:19}}; | Add missing property. | TypeScript |
val index: Int = 'value' | val index: String = 'value' | Fix type. | Kotlin |
$x = 5; print $x | $x = 5; print $x; | Missing semicolon. | Perl |
class Child Base: | class Child(Base): | Inheritance uses parentheses. | Python |
let c = 2; c += 1; | let mut c = 2; c += 1; | Need mut to modify. | Rust |
while foo > 21
foo -= 1 | while foo > 21:
foo -= 1 | Colon missing after while. | Python |
count = info | count = 'info' | Quote strings. | Python |
<img src='info.jpg'> | <img src='info.jpg' alt='desc'> | Add alt text. | HTML |
{ "name": "output" } | { "name": "output" } | Correct. | JSON |
with open('log.txt') as file_handle:
data = file_handle.read() | with open('log.txt') as file_handle:
data = file_handle.read() | Correct. | Python |
name: message
age: 78 | name: message
age: 78 | Correct. | YAML |
var x = 11; | var x = 11; | Correct. | Dart |
println('message') | println("message") | Double quotes. | Scala |
jwt.sign({{id:26}}, 'password'); | jwt.sign({{id:26}}, 'password', {{expiresIn:'2h'}}); | Add expiration. | Node.js |
[x*x for x in data if x > 81] | [x*x for x in data if x > 81] | Correct list comprehension. | Python |
SELECT * FROM items WHRE id=60; | SELECT * FROM items WHERE id=60; | Fix WHERE. | SQL |
[78, 55, 51 | [78, 55, 51] | Close bracket. | Python |
if (x = 91) | if (x == 91) | Use ==. | R |
if (z = 23) {{}} | if (z === 23) {{}} | Use === for equality. | JavaScript |
if count > 19
print('message') | if count > 19:
print('message') | Colon missing after if. | Python |
'82' + 77 | 82 + 77 | Avoid string coercion. | JavaScript |
val y = 89; y = 84 | var y = 89; y = 84 | Use var for reassignment. | Scala |
let v=vec![68,12,52]; let primary=&v[0]; v.push(80); | let mut v=vec![68,12,52]; let primary=v[0]; v.push(80); | Copy instead of reference. | Rust |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
let mut b=17; let r1=&mut b; let r2=&mut b; | let mut b=17; {{ let r1=&mut b; }} let r2=&mut b; | Only one mutable borrow. | Rust |
def handle(item):
return item + 1 | def handle(item):
return item + 1 | Correct. | Python |
if ($num = 72) | if ($num == 72) | Use ==. | Perl |
UPDATE items SET email='value' WHERE status=36 | UPDATE items SET email='value' WHERE status=36; | Add semicolon. | SQL |
List<int> list = [1,2,3]; | List<int> list = [1,2,3]; | Correct. | Dart |
const int x; x = 5; | const int x = 5; | Const must be initialized. | C++ |
if b = 6 then
print('data')
end | if b == 6 then
print('data')
end | Use ==. | Lua |
item == '34' | item === 34 | Use strict equality. | JavaScript |
if a = 54 | if a == 54 | Use ==. | Go |
void test();
int main(){{test();}} | void test(); // prototype
int main(){{test();}} | Declare before use. | C++ |
int values[4]; values[4]=5; | int values[4]; if(4<4){{}} else values[4]=5; | Bounds check. | C++ |
class User
def method
end
end | class User
def method
end
end | Correct. | Ruby |
<ul><li>hello<li>data</ul> | <ul><li>hello</li><li>data</li></ul> | Close li. | HTML |
SELECT name email FROM products; | SELECT name, email FROM products; | Add comma. | SQL |
class Product {{ int count; }}; | class Product {{ public: int count; }}; | Make public. | C++ |
c = 63 | c=63 | No spaces. | Shell |
<hr></hr> | <hr> | Self-closing. | HTML |
{{'name':'output'}} | {{"name":"output"}} | Use double quotes. | JSON |
if c = 80 {{}} | if c == 80 {{}} | Use ==. | Swift |
70c = 10 | c70 = 10 | Variable cannot start with digit. | Python |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
items(8) | if length(items) >= 8, items(8), end | Check length. | MATLAB |
const z = 99; z = 2; | let z = 99; z = 2; | Cannot reassign const. | JavaScript |
var x = 48; | var x = 48; | Correct. | Dart |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
var x int | var x int | Correct. | Go |
h1 {{ font-size:5px color:blue; }} | h1 {{ font-size:5px; color:blue; }} | Add semicolon. | CSS |
if (item) console.log('yes') else console.log('no') | if (item) console.log('yes'); else console.log('no'); | Missing semicolon. | JavaScript |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
for i=1,20 do print(i) end | for i=1,20 do print(i) end | Correct. | Lua |
'23' + 75 | 23 + 75 | Avoid string coercion. | JavaScript |
object Product {{ def main(args: Array[String]) = println("hello") }} | object Product {{ def main(args: Array[String]): Unit = println("hello") }} | Add return type Unit. | Scala |
<div color=green> | <div style='color:green;'> | Use style attribute. | CSS |
$x = 5; print $x | $x = 5; print $x; | Missing semicolon. | Perl |
p {{ color: red }} | p {{ color: red; }} | Add semicolon. | CSS |
local bar = 85 | local bar = 85 | Correct. | Lua |
List<int> list = [1,2,3]; | List<int> list = [1,2,3]; | Correct. | Dart |
DELETE FROM items WHERE name=13 | DELETE FROM items WHERE name=13; | Add semicolon. | SQL |
print('data') | print('data') | Correct. | R |
if (z = 96) {{}} | if (z == 96) {{}} | Use ==. | Kotlin |
if (num = 80) {{}} | if (num === 80) {{}} | Use === for equality. | JavaScript |
{{"id":"world" "title":9}} | {{"id":"world", "title":9}} | Add comma. | JSON |
int z = 'value'; | String z = 'value'; | Type mismatch. | Dart |
INSERT INTO products VALUES ('message',87) | INSERT INTO products (id, status) VALUES ('message',87); | Specify columns. | SQL |
int &ref; | int x; int &ref = x; | Reference must be initialized. | C++ |
let a: i32 = "test"; | let a: &str = "test"; | Type mismatch. | Rust |
<a href='https://demo.net' target='_blank'> | <a href='https://demo.net' target='_blank' rel='noopener'> | Add rel for security. | HTML |
<p>value <b>data</p></b> | <p>value <b>data</b></p> | Nest properly. | HTML |
[27, 16, 83 | [27, 16, 83] | Close bracket. | Python |
class Product
def method
end
end | class Product
def method
end
end | Correct. | Ruby |
SELECT age role FROM users; | SELECT age, role FROM users; | Add comma. | SQL |
count = 43 | count=43 | No spaces. | Shell |
let mut val=68; let ref1=&mut val; let ref2=&mut val; | let mut val=68; {{ let ref1=&mut val; }} let ref2=&mut val; | Only one mutable borrow. | Rust |
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