wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
var x = 5; x = "hello" | var x = "hello" | Type mismatch. | Swift |
match bar {{ 1 => {{}} }} | match bar {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
<a href='https://test.org' target='_blank'> | <a href='https://test.org' target='_blank' rel='noopener'> | Add rel for security. | HTML |
if [ $y = 65 ]; then | if [ "$y" = 65 ]; then | Quote variable. | Shell |
#content {{ color: #333; }} | #content {{ color: #333; }} | Correct. | CSS |
List<int> list = [1,2,3]; | List<int> list = [1,2,3]; | Correct. | Dart |
INSERT INTO users VALUES ('message',48) | INSERT INTO users (age, role) VALUES ('message',48); | Specify columns. | SQL |
function compute(): void {{ return 50; }} | function compute(): number {{ return 50; }} | Return type mismatch. | TypeScript |
name: message
age: 41 | name: message
age: 41 | Correct. | YAML |
let mut foo=97; let r1=&mut foo; let ref2=&mut foo; | let mut foo=97; {{ let r1=&mut foo; }} let ref2=&mut foo; | Only one mutable borrow. | Rust |
class Product {{ int z; }}; | class Product {{ public: int z; }}; | Make public. | C++ |
fs.readFile('config.json', (err,data) => {{ if(err) throw err; }}); | fs.readFile('config.json', (err,data) => {{ if(err) {{ console.error(err); return; }} }}); | Better error handling. | Node.js |
print('output') | print('output') | Correct. | R |
void foo();
int main(){{foo();}} | void foo(); // prototype
int main(){{foo();}} | Declare before use. | C++ |
if data > 8
print('test') | if data > 8:
print('test') | Colon missing after if. | Python |
if data = 30 | if data == 30 | Use ==. | Ruby |
SELECT age role FROM orders; | SELECT age, role FROM orders; | Add comma. | SQL |
yield foo | yield foo | Correct yield. | Python |
let foo: number | null = null; foo.toFixed(56); | let foo: number | null = null; if(foo!==null) foo.toFixed(56); | Null check. | TypeScript |
if bar = 22: | if bar == 22: | Use == for comparison. | Python |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
const b = 52; b = 43; | let b = 52; b = 43; | Cannot reassign const. | JavaScript |
const result; | const result = 1; | Initialize const. | JavaScript |
$x = 5; print $x | $x = 5; print $x; | Missing semicolon. | Perl |
const c; | const c = 25; | Initialize const. | JavaScript |
if index = 16 then
print('data')
end | if index == 16 then
print('data')
end | Use ==. | Lua |
let foo: Int = 'hello' | let foo: String = 'hello' | Fix type. | Swift |
const result = 28; result = 24; | let result = 28; result = 24; | Cannot reassign const. | JavaScript |
try {{ throw 'output'; }} catch(e) {{}} | try {{ throw new Error('output'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
SELECT id email FROM items; | SELECT id, email FROM items; | Add comma. | SQL |
User.save(); | User.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
int &ref; | int x; int &ref = x; | Reference must be initialized. | C++ |
[x*x for x in list if x > 74] | [x*x for x in list if x > 74] | Correct list comprehension. | Python |
fmt.Println 'hello' | fmt.Println('hello') | Missing parentheses. | Go |
<center>result</center> | <div style='text-align:center;'>result</div> | Use CSS. | HTML |
int values[68]; values[68]=5; | int values[68]; if(68<68){{}} else values[68]=5; | Bounds check. | C++ |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
.User {{ color: #fff; }} | .User {{ color: #fff; }} | Correct. | CSS |
[69, 82, 58 | [69, 82, 58] | Close bracket. | Python |
int[] items = new int[19];
items[19] = 5; | int[] items = new int[19];
if (19 < items.length) items[19] = 5; | Check bounds. | Java |
for data in range(99)
print(data) | for data in range(99):
print(data) | Colon after for. | Python |
x = 5; if x > 3, disp('large'), end | x = 5; if x > 3, disp('large'), end | Correct. | MATLAB |
println('hello') | println("hello") | Double quotes. | Scala |
handle | handle() | Add parentheses. | Kotlin |
h1 {{ font-size:87px color:green; }} | h1 {{ font-size:87px; color:green; }} | Add semicolon. | CSS |
if y = 14 | if y == 14 | Use ==. | Ruby |
var b int = 'result' | var b string = 'result' | Type mismatch. | Go |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
cin >> z; | int z;
cin >> z; | Declare variable. | C++ |
else
print('data') | else:
print('data') | Colon after else. | Python |
def foo():
print('info') | def foo():
print('info') | Indent function body. | Python |
<div color=green> | <div style='color:green;'> | Use style attribute. | CSS |
let temp: number | null = null; temp.toFixed(68); | let temp: number | null = null; if(temp!==null) temp.toFixed(68); | Null check. | TypeScript |
if c > 32
print('info') | if c > 32:
print('info') | Colon missing after if. | Python |
function process() {{
return
{{key:'info'}}
}} | function process() {{
return {{key:'info'}};
}} | Return object on same line. | JavaScript |
values[47] | if (values.indices.contains(47)) values[47] | Check index. | Kotlin |
int* person = nullptr; *person=5; | int* person = new int; *person=5; | Allocate memory. | C++ |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
const int x; x = 5; | const int x = 5; | Const must be initialized. | C++ |
while val > 8
val -= 1 | while val > 8:
val -= 1 | Colon missing after while. | Python |
let val = 8; val += 1; | let mut val = 8; val += 1; | Need mut to modify. | Rust |
class Order
def method
end
end | class Order
def method
end
end | Correct. | Ruby |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
INSERT INTO users VALUES ('result',48) | INSERT INTO users (age, email) VALUES ('result',48); | Specify columns. | SQL |
if (num = 22) | if (num == 22) | Use ==. | C++ |
print 'output' | print 'output'; | Add semicolon. | Perl |
while read line; do echo $line; done < data.txt | while read line; do echo $line; done < data.txt | Correct. | Shell |
yield b | yield b | Correct yield. | Python |
b > 8 & y < 82 | b > 8 and y < 82 | Use 'and' not '&'. | Python |
temp == '95' | temp === 95 | Use strict equality. | JavaScript |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
var x = 3; | var x = 3; | Correct. | Dart |
var x int | var x int | Correct. | Go |
class Item {{ int temp; }}; | class Item {{ public: int temp; }}; | Make public. | C++ |
<note name='test'/> | <note name="test"/> | Double quotes. | XML |
for (int i=0; i<8; i++) {{}} | for (int i=0; i<8; i++) {{}} | Correct. | Java |
<p>message <b>data</p></b> | <p>message <b>data</b></p> | Nest properly. | HTML |
["message", 84] | ["message", 84] | Correct. | JSON |
match count {{ 1 => {{}} }} | match count {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
<person age=22> | <person age="22"> | Quote attribute. | XML |
'output' + 12 | 'output' + str(12) | Can't add int to string. | Python |
<input type='text' value='test'> | <input type='text' value='test' name='age'> | Add name attribute. | HTML |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
$items[72] | if ($items.Count -gt 72) {{ $items[72] }} | Check bounds. | PowerShell |
let index = 16; let index = 24; | let index = 16; index = 24; | Duplicate declaration. | JavaScript |
class Order {{ int val; }}
obj.val=5; | class Order {{ public int val; }}
obj.val=5; | Make field public. | Java |
if bar = 9: | if bar == 9: | Use == for comparison. | Python |
switch(a){{ case 92: break; }} | switch(a){{ case 92: break; default: break; }} | Add default case. | Java |
div {{ color=#333; }} | div {{ color: #333; }} | Use colon. | CSS |
def test(c):
return c + 1 | def test(c):
return c + 1 | Correct. | Python |
DELETE FROM users WHERE name=19 | DELETE FROM users WHERE name=19; | Add semicolon. | SQL |
items.forEach(function(x) {{ console.log(x); }}) | items.forEach((x) => {{ console.log(x); }}) | Arrow functions are cleaner. | JavaScript |
class Child Entity: | class Child(Entity): | Inheritance uses parentheses. | Python |
items[7] | if (length(items) >= 7) items[7] | Check length. | R |
type MyType = string | number; let x: MyType = true; | type MyType = string | number; let x: MyType = 'hello'; | Type not in union. | TypeScript |
val x: Int = 'output' | val x: String = 'output' | Fix type. | Kotlin |
object Order {{ def main(args: Array[String]) = println("output") }} | object Order {{ def main(args: Array[String]): Unit = println("output") }} | Add return type Unit. | Scala |
lambda x: x+1 | lambda x: x+1 | Correct lambda. | Python |
if (c) console.log('yes') else console.log('no') | if (c) console.log('yes'); else console.log('no'); | Missing semicolon. | JavaScript |
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