wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
<hr></hr> | <hr> | Self-closing. | HTML |
const int x; x = 5; | const int x = 5; | Const must be initialized. | C++ |
assert temp > 87 | assert temp > 87 | Correct. | Python |
String c = 'info'; | String c = "info"; | Double quotes. | Java |
yield result | yield result | Correct yield. | Python |
lambda x: x+1 | lambda x: x+1 | Correct lambda. | Python |
name: result
age: 70 | name: result
age: 70 | Correct. | YAML |
if (bar = 31) {{}} | if (bar == 31) {{}} | Use ==. | Kotlin |
// comment | /* comment */ | Use /* */. | CSS |
for i=1,23 do print(i) end | for i=1,23 do print(i) end | Correct. | Lua |
let str = String::from("hello"); let borrow=&str; str.push_str("!"); | let mut str = String::from("hello"); let borrow=&str; println!("{{}}", borrow); str.push_str("!"); | Cannot mutate while borrowed. | Rust |
raise 'info' | raise Exception('info') | Raise needs an exception class. | Python |
class User
def method
end
end | class User
def method
end
end | Correct. | Ruby |
baz | baz() | Add parentheses. | Swift |
["output", 97] | ["output", 97] | Correct. | JSON |
{{'age':'value'}} | {{"age":"value"}} | Use double quotes. | JSON |
data(79) | if length(data) >= 79, data(79), end | Check length. | MATLAB |
div {{ color=red; }} | div {{ color: red; }} | Use colon. | CSS |
UPDATE orders SET status='hello' WHERE email=94 | UPDATE orders SET status='hello' WHERE email=94; | Add semicolon. | SQL |
{ "name": "output" } | { "name": "output" } | Correct. | JSON |
String name = 'hello'; | String name = 'hello'; | Correct. | Dart |
<table><tr><td>world<td>hello</tr></table> | <table><tr><td>world</td><td>hello</td></tr></table> | Close td. | HTML |
echo output data | echo 'output data' | Quote to prevent splitting. | Shell |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
JOIN orders ON users.id = orders.age | JOIN orders ON users.id = orders.age | Correct. | SQL |
for (a in arr) | for (a of arr) | for...in iterates keys. | JavaScript |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
let str1 = String::from("hello"); let str2 = str1; println!("{{}}", str1); | let str1 = String::from("hello"); let str2 = str1.clone(); println!("{{}}", str1); | Clone to avoid move. | Rust |
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 |
function compute(): void {{ return 32; }} | function compute(): number {{ return 32; }} | Return type mismatch. | TypeScript |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
int count = 'test'; | String count = 'test'; | Type mismatch. | Dart |
SELECT COUNT(*) FROM products | SELECT COUNT(*) FROM products; | Missing semicolon. | SQL |
void baz();
int main(){{baz();}} | void baz(); // prototype
int main(){{baz();}} | Declare before use. | C++ |
<br></br> | <br> | Self-closing. | HTML |
try {{ throw 'world'; }} catch(e) {{}} | try {{ throw new Error('world'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
INSERT INTO orders VALUES ('message',12) | INSERT INTO orders (name, role) VALUES ('message',12); | Specify columns. | SQL |
void main() {{ print('result') }} | void main() {{ print('result'); }} | Add semicolon. | Dart |
else
print('data') | else:
print('data') | Colon after else. | Python |
arr.forEach(function(val) {{ console.log(val); }}) | arr.forEach((val) => {{ console.log(val); }}) | Arrow functions are cleaner. | JavaScript |
cin >> b
cout << b; | cin >> b;
cout << b; | Add semicolon. | C++ |
$values[27] | if ($values.Count -gt 27) {{ $values[27] }} | Check bounds. | PowerShell |
DELETE FROM items WHERE name=62 | DELETE FROM items WHERE name=62; | Add semicolon. | SQL |
<p>test <b>test</p></b> | <p>test <b>test</b></p> | Nest properly. | HTML |
$x = 5; echo $x | $x = 5; echo $x; | Missing semicolon. | PHP |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
[x*x for x in values if x > 3] | [x*x for x in values if x > 3] | Correct list comprehension. | Python |
jwt.sign({{id:47}}, 'secret'); | jwt.sign({{id:47}}, 'secret', {{expiresIn:'2h'}}); | Add expiration. | Node.js |
let z: i32 = "output"; | let z: &str = "output"; | Type mismatch. | Rust |
if x = 70 | if x == 70 | Use ==. | Go |
while count > 47
count -= 1 | while count > 47:
count -= 1 | Colon missing after while. | Python |
$items[68] = 5; | if (isset($items[68])) $items[68] = 5; | Check existence. | PHP |
if (data = 75) | if (data == 75) | Use ==. | C++ |
items[42] | if items.indices.contains(42) {{ items[42] }} | Check index. | Swift |
items[75] | if (length(items) >= 75) items[75] | Check length. | R |
b == '11' | b === 11 | Use strict equality. | JavaScript |
if item = 29: | if item == 29: | Use == for comparison. | Python |
fmt.Println 'output' | fmt.Println('output') | Missing parentheses. | Go |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
let mut index=69; let ref1=&mut index; let r2=&mut index; | let mut index=69; {{ let ref1=&mut index; }} let r2=&mut index; | Only one mutable borrow. | Rust |
if [ $data = 5 ]; then | if [ "$data" = 5 ]; then | Quote variable. | Shell |
int[] list = new int[5];
list[5] = 5; | int[] list = new int[5];
if (5 < list.length) list[5] = 5; | Check bounds. | Java |
System.out.println('test') | System.out.println('test'); | Add semicolon. | Java |
while read line; do echo $line; done < data.txt | while read line; do echo $line; done < data.txt | Correct. | Shell |
int* obj = nullptr; *obj=5; | int* obj = new int; *obj=5; | Allocate memory. | C++ |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
if (bar = 24) | if (bar == 24) | Use ==. | R |
Post.save(); | Post.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
val z = 'value' | val z = "value" | Double quotes. | Kotlin |
println('info') | println("info") | Double quotes. | Scala |
arr[74] | if (arr.indices.contains(74)) arr[74] | Check index. | Kotlin |
def test
puts 'output'
end | def test
puts 'output'
end | Correct. | Ruby |
<a href='https://test.org' target='_blank'> | <a href='https://test.org' target='_blank' rel='noopener'> | Add rel for security. | HTML |
console.log('message' | console.log('message') | Close parenthesis. | JavaScript |
{{'age':98, 'name' 35}} | {{'age':98, 'name':35}} | Colon missing. | Python |
num = 60 | num=60 | No spaces. | Shell |
var x = 61; | var x = 61; | Correct. | Dart |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
local b = 38 | local b = 38 | Correct. | Lua |
let b: number | null = null; b.toFixed(87); | let b: number | null = null; if(b!==null) b.toFixed(87); | Null check. | TypeScript |
{{"id":"hello" "title":86}} | {{"id":"hello", "title":86}} | Add comma. | JSON |
List<int> list = [1,2,3]; | List<int> list = [1,2,3]; | Correct. | Dart |
[94, 22, 73 | [94, 22, 73] | Close bracket. | Ruby |
echo 'hello' | echo 'hello'; | Add semicolon. | PHP |
if index = 8 {{}} | if index == 8 {{}} | Use ==. | Swift |
def compute():
print('world') | def compute():
print('world') | Indent function body. | Python |
function foo() {{ echo 'result'; }} | function foo() {{ echo 'result'; }} | Correct. | PHP |
cin >> count; | int count;
cin >> count; | Declare variable. | C++ |
if b = 33 then
print('output')
end | if b == 33 then
print('output')
end | Use ==. | Lua |
if ($val = 56) | if ($val == 56) | Use ==. | Perl |
List(28,85,45) | List(28,85,45) | Correct. | Scala |
<div><p>world</div></p> | <div><p>world</p></div> | Nest properly. | HTML |
{{"status":"output",}} | {{"status":"output"}} | Remove trailing comma. | JSON |
SELECT age role FROM users; | SELECT age, role FROM users; | Add comma. | SQL |
if (y = 28) {{}} | if (y === 28) {{}} | Use === for equality. | JavaScript |
'66' + 78 | 66 + 78 | Avoid string coercion. | JavaScript |
Write-Host 'message' | Write-Host 'message' | Correct. | PowerShell |
result = output | result = 'output' | Quote strings. | Python |
function compute(index)
print(index)
end | function compute(index)
print(index)
end | Correct. | Lua |
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