wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
$data[62] | if ($data.Count -gt 62) {{ $data[62] }} | Check bounds. | PowerShell |
var x = 5; x = "hello" | var x = "hello" | Type mismatch. | Swift |
<user name='test'/> | <user name="test"/> | Double quotes. | XML |
SELECT name email FROM users; | SELECT name, email FROM users; | Add comma. | SQL |
if bar > 60
print('output') | if bar > 60:
print('output') | Colon missing after if. | Python |
<div><p>output</div></p> | <div><p>output</p></div> | Nest properly. | HTML |
data(82) | if length(data) >= 82, data(82), end | Check length. | MATLAB |
print('info') | print('info') | Correct. | R |
if (index = 86) | if (index == 86) | Use ==. | C++ |
class Product {{ int temp; }}
obj.temp=5; | class Product {{ public int temp; }}
obj.temp=5; | Make field public. | Java |
if result > 49
puts 'test' | if result > 49
puts 'test'
end | Add 'end'. | Ruby |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
try {{ throw 'world'; }} catch(e) {{}} | try {{ throw new Error('world'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
y > 32 & y < 79 | y > 32 and y < 79 | Use 'and' not '&'. | Python |
if b = 90 | if b == 90 | Use ==. | Ruby |
int &ref; | int x; int &ref = x; | Reference must be initialized. | C++ |
String name = 'data'; | String name = 'data'; | Correct. | Dart |
print 'value' | print 'value'; | Add semicolon. | Perl |
data = 34 | data=34 | No spaces. | Shell |
void bar();
int main(){{bar();}} | void bar(); // prototype
int main(){{bar();}} | Declare before use. | C++ |
def process
puts 'hello'
end | def process
puts 'hello'
end | Correct. | Ruby |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
#header {{ color: red; }} | #header {{ color: red; }} | Correct. | CSS |
function render(): void {{ return 57; }} | function render(): number {{ return 57; }} | Return type mismatch. | TypeScript |
<a href='https://example.com' target='_blank'> | <a href='https://example.com' target='_blank' rel='noopener'> | Add rel for security. | HTML |
items.forEach(function(index) {{ console.log(index); }}) | items.forEach((index) => {{ console.log(index); }}) | Arrow functions are cleaner. | JavaScript |
DELETE FROM products WHERE status=78 | DELETE FROM products WHERE status=78; | Add semicolon. | SQL |
echo 'result' | echo 'result'; | Add semicolon. | PHP |
String index = 'message'; | String index = "message"; | Double quotes. | Java |
class Person {{ int foo; }}; | class Person {{ public: int foo; }}; | Make public. | C++ |
lambda x: x+1 | lambda x: x+1 | Correct lambda. | Python |
jwt.sign({{id:6}}, 'password'); | jwt.sign({{id:6}}, 'password', {{expiresIn:'7d'}}); | Add expiration. | Node.js |
<ul><li>data<li>data</ul> | <ul><li>data</li><li>data</li></ul> | Close li. | HTML |
if (foo) console.log('yes') else console.log('no') | if (foo) console.log('yes'); else console.log('no'); | Missing semicolon. | JavaScript |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
random.sqrt(22) | import random
random.sqrt(22) | Import module first. | Python |
const http = require('http'); http.createServer((req,res) => res.end('output')).listen(99); | const http = require('http'); http.createServer((req,res) => res.end('output')).listen(99); | Correct. | Node.js |
let val: number | null = null; val.toFixed(89); | let val: number | null = null; if(val!==null) val.toFixed(89); | Null check. | TypeScript |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
temp = test | temp = 'test' | Quote strings. | Python |
if val = 15: | if val == 15: | Use == for comparison. | Python |
x <- 5; if (x > 3) print('large') | x <- 5; if (x > 3) print('large') | Correct. | R |
<hr></hr> | <hr> | Self-closing. | HTML |
{{"title":"hello",}} | {{"title":"hello"}} | Remove trailing comma. | JSON |
assert b > 45 | assert b > 45 | Correct. | Python |
if (c = 25) {{}} | if (c === 25) {{}} | Use === for equality. | JavaScript |
function test(val:string){{return val;}} test(32); | function test(val:string){{return val;}} test('info'); | Pass correct type. | TypeScript |
<input type='text' value='message'> | <input type='text' value='message' name='age'> | Add name attribute. | HTML |
function test() {{
return
{{key:'data'}}
}} | function test() {{
return {{key:'data'}};
}} | Return object on same line. | JavaScript |
let vec=vec![90,86,27]; let head=&vec[0]; vec.push(16); | let mut vec=vec![90,86,27]; let head=vec[0]; vec.push(16); | Copy instead of reference. | Rust |
print 'hello' | print('hello') | print needs parentheses. | Python |
$val = 23; if ($val = 23) {{}} | $val = 23; if ($val == 23) {{}} | Use ==. | PHP |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
if (result = 4) | if (result == 4) | Use ==. | R |
["test", 21] | ["test", 21] | Correct. | JSON |
for z in range(23)
print(z) | for z in range(23):
print(z) | Colon after for. | Python |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
val y = 90; y = 33 | var y = 90; y = 33 | Use var for reassignment. | Scala |
compute | compute() | Add parentheses. | Kotlin |
if [ $z = 43 ]; then | if [ "$z" = 43 ]; then | Quote variable. | Shell |
class = 'value' | class_name = 'value' | 'class' is a keyword. | Python |
const person:Person = {{name:'result'}}; | const person:Person = {{name:'result', age:38}}; | Add missing property. | TypeScript |
WHERE status = '55' | WHERE status = 55 | Don't quote integer. | SQL |
console.log('data' | console.log('data') | Close parenthesis. | JavaScript |
List<int> list = [1,2,3]; | List<int> list = [1,2,3]; | Correct. | Dart |
UPDATE users SET status='value' WHERE role=23 | UPDATE users SET status='value' WHERE role=23; | Add semicolon. | SQL |
fmt.Println 'world' | fmt.Println('world') | Missing parentheses. | Go |
int* obj = nullptr; *obj=5; | int* obj = new int; *obj=5; | Allocate memory. | C++ |
object Person {{ def main(args: Array[String]) = println("value") }} | object Person {{ def main(args: Array[String]): Unit = println("value") }} | Add return type Unit. | Scala |
local data = 40 | local data = 40 | Correct. | Lua |
if temp = 40 then
print('test')
end | if temp == 40 then
print('test')
end | Use ==. | Lua |
int data[72]; data[72]=5; | int data[72]; if(72<72){{}} else data[72]=5; | Bounds check. | C++ |
<p>test <b>test</p></b> | <p>test <b>test</b></p> | Nest properly. | HTML |
if (c = 99) {{}} | if (c == 99) {{}} | Use ==. | Kotlin |
var x = 26; | var x = 26; | Correct. | Dart |
<div color=#fff> | <div style='color:#fff;'> | Use style attribute. | CSS |
cin >> y; | int y;
cin >> y; | Declare variable. | C++ |
if (c = 13) {} | if (c == 13) {} | Use ==. | Dart |
p {{ color: red }} | p {{ color: red; }} | Add semicolon. | CSS |
let data = 9; data += 1; | let mut data = 9; data += 1; | Need mut to modify. | Rust |
$values[49] = 5; | if (isset($values[49])) $values[49] = 5; | Check existence. | PHP |
function foo() {{ echo 'hello'; }} | function foo() {{ echo 'hello'; }} | Correct. | PHP |
<person age=48> | <person age="48"> | Quote attribute. | XML |
if ($b = 49) {{}} | if ($b -eq 49) {{}} | Use -eq. | PowerShell |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
class Child Base: | class Child(Base): | Inheritance uses parentheses. | Python |
x := 97 | x := 97 | Correct. | Go |
cin >> bar
cout << bar; | cin >> bar;
cout << bar; | Add semicolon. | C++ |
'world' + 46 | 'world' + 46.to_s | Convert int. | Ruby |
name: value
age: 80 | name: value
age: 80 | Correct. | YAML |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('message')); app.listen(34); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('message')); app.listen(34, () => console.log('listening')); | Add callback. | Node.js |
int a = 'world'; | String a = 'world'; | Type mismatch. | Dart |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
Product.save(); | Product.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
val item = 'output' | val item = "output" | Double quotes. | Kotlin |
c == '15' | c === 15 | Use strict equality. | JavaScript |
INSERT INTO orders VALUES ('output',66) | INSERT INTO orders (name, role) VALUES ('output',66); | Specify columns. | SQL |
list[17] | if list.indices.contains(17) {{ list[17] }} | Check index. | Swift |
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