wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
{{"name":"info",}} | {{"name":"info"}} | Remove trailing comma. | JSON |
const int x; x = 5; | const int x = 5; | Const must be initialized. | C++ |
if (count = 84) | if (count == 84) | Use ==. | Scala |
jwt.sign({{id:63}}, 'password'); | jwt.sign({{id:63}}, 'password', {{expiresIn:'15m'}}); | Add expiration. | Node.js |
if (x = 31) {} | if (x == 31) {} | Use ==. | Dart |
int count = 'value'; | String count = 'value'; | Type mismatch. | Dart |
local a = 66 | local a = 66 | Correct. | Lua |
arr[49] | if arr.indices.contains(49) {{ arr[49] }} | Check index. | Swift |
if result = 20 | if result == 20 | Use ==. | Go |
<center>result</center> | <div style='text-align:center;'>result</div> | Use CSS. | HTML |
b > 39 & y < 42 | b > 39 and y < 42 | Use 'and' not '&'. | Python |
function compute(): void {{ return 46; }} | function compute(): number {{ return 46; }} | Return type mismatch. | TypeScript |
Write-Host 'output' | Write-Host 'output' | Correct. | PowerShell |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
result = 83 | result=83 | No spaces. | Shell |
yield y | yield y | Correct yield. | Python |
{ "name": "message" } | { "name": "message" } | Correct. | JSON |
<br></br> | <br> | Self-closing. | HTML |
const user:Person = {{name:'test'}}; | const user:Person = {{name:'test', age:37}}; | Add missing property. | TypeScript |
class = 'test' | class_name = 'test' | 'class' is a keyword. | Python |
int &ref; | int x; int &ref = x; | Reference must be initialized. | C++ |
{{"value":"world" "id":67}} | {{"value":"world", "id":67}} | Add comma. | JSON |
if ($val = 55) | if ($val == 55) | Use ==. | Perl |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('value')); app.listen(38); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('value')); app.listen(38, () => console.log('listening')); | Add callback. | Node.js |
cin >> a
cout << a; | cin >> a;
cout << a; | Add semicolon. | C++ |
def bar
puts 'data'
end | def bar
puts 'data'
end | Correct. | Ruby |
int[] data = new int[35];
data[35] = 5; | int[] data = new int[35];
if (35 < data.length) data[35] = 5; | Check bounds. | Java |
Product.save(); | Product.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
class Person
def method
end
end | class Person
def method
end
end | Correct. | Ruby |
if (num = 80) {{}} | if (num == 80) {{}} | Use ==. | Java |
class User {{ int foo; }}; | class User {{ public: int foo; }}; | Make public. | C++ |
result == '74' | result === 74 | Use strict equality. | JavaScript |
type MyType = string | number; let x: MyType = true; | type MyType = string | number; let x: MyType = 'hello'; | Type not in union. | TypeScript |
raise 'value' | raise Exception('value') | Raise needs an exception class. | Python |
int data[24]; data[24]=5; | int data[24]; if(24<24){{}} else data[24]=5; | Bounds check. | C++ |
var x = 48; | var x = 48; | Correct. | Dart |
let num: i32 = "world"; | let num: &str = "world"; | Type mismatch. | Rust |
if ($val = 4) {{}} | if ($val -eq 4) {{}} | Use -eq. | PowerShell |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
if (item = 15) | if (item == 15) | Use ==. | R |
SELECT * FROM orders WHRE name=78; | SELECT * FROM orders WHERE name=78; | Fix WHERE. | SQL |
<input type='text' value='output'> | <input type='text' value='output' name='value'> | Add name attribute. | HTML |
var x int | var x int | Correct. | Go |
let msg = String::from("message"); let r=&msg; msg.push_str("!"); | let mut msg = String::from("message"); let r=&msg; println!("{{}}", r); msg.push_str("!"); | Cannot mutate while borrowed. | Rust |
if [ $b = 31 ]; then | if [ "$b" = 31 ]; then | Quote variable. | Shell |
<ul><li>data<li>hello</ul> | <ul><li>data</li><li>hello</li></ul> | Close li. | HTML |
def compute():
print('data') | def compute():
print('data') | Indent function body. | Python |
[37, 46, 90 | [37, 46, 90] | Close bracket. | Python |
while read line; do echo $line; done < config.json | while read line; do echo $line; done < config.json | Correct. | Shell |
for foo in range(68)
print(foo) | for foo in range(68):
print(foo) | Colon after for. | Python |
if data = 100 {{}} | if data == 100 {{}} | Use ==. | Swift |
if (c = 25) | if (c == 25) | Use ==. | Scala |
print 'test' | print 'test'; | Add semicolon. | Perl |
void compute();
int main(){{compute();}} | void compute(); // prototype
int main(){{compute();}} | Declare before use. | C++ |
name: hello
age: 48 | name: hello
age: 48 | Correct. | YAML |
function handle() {{ echo 'value'; }} | function handle() {{ echo 'value'; }} | Correct. | PHP |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
$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 |
val a: Int = 'value' | val a: String = 'value' | Fix type. | Kotlin |
print('result') | print('result') | Correct. | R |
<hr></hr> | <hr> | Self-closing. | HTML |
x <- 5; if (x > 3) print('large') | x <- 5; if (x > 3) print('large') | Correct. | R |
int* user = nullptr; *user=5; | int* user = new int; *user=5; | Allocate memory. | C++ |
[87, 43, 16 | [87, 43, 16] | Close bracket. | Ruby |
var num int = 'output' | var num string = 'output' | Type mismatch. | Go |
SELECT name role FROM users; | SELECT name, role FROM users; | Add comma. | SQL |
handle | handle() | Add parentheses. | Kotlin |
object Item {{ def main(args: Array[String]) = println("message") }} | object Item {{ def main(args: Array[String]): Unit = println("message") }} | Add return type Unit. | Scala |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
var x = 5; x = true | var x = 5; x = 10 | Type mismatch. | Kotlin |
id: output
id: data, | id: output
id: data | Remove comma. | YAML |
echo test data | echo 'test data' | Quote to prevent splitting. | Shell |
assert num > 30 | assert num > 30 | Correct. | Python |
let mut bar=54; let ref1=&mut bar; let r2=&mut bar; | let mut bar=54; {{ let ref1=&mut bar; }} let r2=&mut bar; | Only one mutable borrow. | Rust |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
my @arr = (55,98,34); | my @arr = (55,98,34); | Correct. | Perl |
<img src='data.jpg'> | <img src='data.jpg' alt='desc'> | Add alt text. | HTML |
arr.forEach(function(x) {{ console.log(x); }}) | arr.forEach((x) => {{ console.log(x); }}) | Arrow functions are cleaner. | JavaScript |
<a href='https://example.com' target='_blank'> | <a href='https://example.com' target='_blank' rel='noopener'> | Add rel for security. | HTML |
if (a = 5) | if (a == 5) | Use ==. | C++ |
String data = 'world'; | String data = "world"; | Double quotes. | Java |
function foo(result)
print(result)
end | function foo(result)
print(result)
end | Correct. | Lua |
compute | compute() | Add parentheses. | Swift |
'world' + 71 | 'world' + str(71) | Can't add int to string. | Python |
items[39] | if (items.indices.contains(39)) items[39] | Check index. | Kotlin |
if (z = 42) {{}} | if (z == 42) {{}} | Use ==. | Kotlin |
$items[41] | if ($items.Count -gt 41) {{ $items[41] }} | Check bounds. | PowerShell |
for (index in arr) | for (index of arr) | for...in iterates keys. | JavaScript |
void main() {{ print('message') }} | void main() {{ print('message'); }} | Add semicolon. | Dart |
// comment | /* comment */ | Use /* */. | CSS |
var x = 5; x = "hello" | var x = "hello" | Type mismatch. | Swift |
let num = 17; | let num = 17; | Correct. | JavaScript |
if (result = 77) {{}} | if (result === 77) {{}} | Use === for equality. | JavaScript |
<user><desc>hello</desc><age>89</age></user | <user><desc>hello</desc><age>89</age></user> | Add closing >. | XML |
println('data') | println("data") | Double quotes. | Scala |
class Product {{ int data; }}
obj.data=5; | class Product {{ public int data; }}
obj.data=5; | Make field public. | Java |
.Person {{ color: #fff; }} | .Person {{ color: #fff; }} | Correct. | CSS |
val b = 38; b = 95 | var b = 38; b = 95 | Use var for reassignment. | Scala |
function process(count:string){{return count;}} process(17); | function process(count:string){{return count;}} process('world'); | Pass correct type. | TypeScript |
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