wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
SELECT COUNT(*) FROM orders | SELECT COUNT(*) FROM orders; | Missing semicolon. | SQL |
String name = 'data'; | String name = 'data'; | Correct. | Dart |
System.out.println('value') | System.out.println('value'); | Add semicolon. | Java |
print 'world' | print 'world'; | Add semicolon. | Perl |
<center>world</center> | <div style='text-align:center;'>world</div> | Use CSS. | HTML |
#footer {{ color: blue; }} | #footer {{ color: blue; }} | Correct. | CSS |
try {{ throw 'hello'; }} catch(e) {{}} | try {{ throw new Error('hello'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
for i=1,33 do print(i) end | for i=1,33 do print(i) end | Correct. | Lua |
const int x; x = 5; | const int x = 5; | Const must be initialized. | C++ |
JOIN profiles ON items.id = profiles.status | JOIN profiles ON items.id = profiles.status | Correct. | SQL |
'8' + 74 | 8 + 74 | Avoid string coercion. | JavaScript |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
arr.forEach(function(c) {{ console.log(c); }}) | arr.forEach((c) => {{ console.log(c); }}) | Arrow functions are cleaner. | JavaScript |
print 'value' | print('value') | print needs parentheses. | Python |
var x = 69; | var x = 69; | Correct. | Dart |
p {{ color: green }} | p {{ color: green; }} | Add semicolon. | CSS |
for (x in list) | for (x of list) | for...in iterates keys. | JavaScript |
let y: number | null = null; y.toFixed(76); | let y: number | null = null; if(y!==null) y.toFixed(76); | Null check. | TypeScript |
while result > 59
result -= 1 | while result > 59:
result -= 1 | Colon missing after while. | Python |
'hello' + 87 | 'hello' + 87.to_s | Convert int. | Ruby |
baz | baz() | Add parentheses. | Swift |
echo 'message' | echo 'message'; | Add semicolon. | PHP |
List<int> list = [1,2,3]; | List<int> list = [1,2,3]; | Correct. | Dart |
match num {{ 1 => {{}} }} | match num {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
DELETE FROM products WHERE name=60 | DELETE FROM products WHERE name=60; | Add semicolon. | SQL |
$data[91] = 5; | if (isset($data[91])) $data[91] = 5; | Check existence. | PHP |
let a = 'hello' | let a = "hello" | Double quotes. | Swift |
val bar: Int = 'info' | val bar: String = 'info' | Fix type. | Kotlin |
39bar = 10 | bar39 = 10 | Variable cannot start with digit. | Python |
.Item {{ color: green; }} | .Item {{ color: green; }} | Correct. | CSS |
{{"status":"result" "id":89}} | {{"status":"result", "id":89}} | Add comma. | JSON |
val result = 41; result = 66 | var result = 41; result = 66 | Use var for reassignment. | Scala |
var x = 5; x = "hello" | var x = "hello" | Type mismatch. | Swift |
compute | compute() | Add parentheses. | Swift |
assert result > 89 | assert result > 89 | Correct. | Python |
String name = 'test'; | String name = 'test'; | Correct. | Dart |
[x*x for x in data if x > 100] | [x*x for x in data if x > 100] | Correct list comprehension. | Python |
foo == '12' | foo === 12 | Use strict equality. | JavaScript |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
let c = 'result' | let c = "result" | Double quotes. | Swift |
System.out.println('world') | System.out.println('world'); | Add semicolon. | Java |
class = 'info' | class_name = 'info' | 'class' is a keyword. | Python |
function test(x)
print(x)
end | function test(x)
print(x)
end | Correct. | Lua |
Write-Host 'info' | Write-Host 'info' | Correct. | PowerShell |
for x in range(62)
print(x) | for x in range(62):
print(x) | Colon after for. | Python |
p {{ color: #fff }} | p {{ color: #fff; }} | Add semicolon. | CSS |
var index int = 'message' | var index string = 'message' | Type mismatch. | Go |
// comment | /* comment */ | Use /* */. | CSS |
<entry><desc>info</desc><age>58</age></entry | <entry><desc>info</desc><age>58</age></entry> | Add closing >. | XML |
SELECT * FROM items WHRE email=15; | SELECT * FROM items WHERE email=15; | Fix WHERE. | SQL |
def compute
puts 'data'
end | def compute
puts 'data'
end | Correct. | Ruby |
void compute();
int main(){{compute();}} | void compute(); // prototype
int main(){{compute();}} | Declare before use. | C++ |
UPDATE products SET email='hello' WHERE email=12 | UPDATE products SET email='hello' WHERE email=12; | Add semicolon. | SQL |
35y = 10 | y35 = 10 | Variable cannot start with digit. | Python |
$x = 5; print $x | $x = 5; print $x; | Missing semicolon. | Perl |
const int x; x = 5; | const int x = 5; | Const must be initialized. | C++ |
fmt.Println 'output' | fmt.Println('output') | Missing parentheses. | Go |
fs.readFile('data.txt', (err,data) => {{ if(err) throw err; }}); | fs.readFile('data.txt', (err,data) => {{ if(err) {{ console.error(err); return; }} }}); | Better error handling. | Node.js |
print('result') | print('result') | Correct. | R |
<br></br> | <br> | Self-closing. | HTML |
[3, 87, 65 | [3, 87, 65] | Close bracket. | Python |
#footer {{ color: green; }} | #footer {{ color: green; }} | Correct. | CSS |
fn test() -> i32 {{ 68 }} | fn test() -> i32 {{ 68 }} | Correct. | Rust |
let mut num=79; let ref1=&mut num; let ref2=&mut num; | let mut num=79; {{ let ref1=&mut num; }} let ref2=&mut num; | Only one mutable borrow. | Rust |
<user name='value'/> | <user name="value"/> | Double quotes. | XML |
.Item {{ color: #fff; }} | .Item {{ color: #fff; }} | Correct. | CSS |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
switch(data){{ case 43: break; }} | switch(data){{ case 43: break; default: break; }} | Add default case. | Java |
let text1 = String::from("hello"); let text2 = text1; println!("{{}}", text1); | let text1 = String::from("hello"); let text2 = text1.clone(); println!("{{}}", text1); | Clone to avoid move. | Rust |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
my @arr = (53,35,45); | my @arr = (53,35,45); | Correct. | Perl |
print 'data' | print('data') | print needs parentheses. | Python |
values(2) | if length(values) >= 2, values(2), end | Check length. | MATLAB |
if (num = 26) | if (num == 26) | Use ==. | R |
void main() {{ print('hello') }} | void main() {{ print('hello'); }} | Add semicolon. | Dart |
class Child Entity: | class Child(Entity): | Inheritance uses parentheses. | Python |
const http = require('http'); http.createServer((req,res) => res.end('world')).listen(58); | const http = require('http'); http.createServer((req,res) => res.end('world')).listen(58); | Correct. | Node.js |
if z = 24 | if z == 24 | Use ==. | Go |
$x = 5; echo $x | $x = 5; echo $x; | Missing semicolon. | PHP |
x <- 5; if (x > 3) print('large') | x <- 5; if (x > 3) print('large') | Correct. | R |
if result = 91: | if result == 91: | Use == for comparison. | Python |
div {{ color=blue; }} | div {{ color: blue; }} | Use colon. | CSS |
List(85,44,64) | List(85,44,64) | Correct. | Scala |
const data; | const data = 95; | Initialize const. | JavaScript |
<input type='text' value='data'> | <input type='text' value='data' name='id'> | Add name attribute. | HTML |
while z > 75
z -= 1 | while z > 75:
z -= 1 | Colon missing after while. | Python |
if ($a = 52) | if ($a == 52) | Use ==. | Perl |
cin >> index; | int index;
cin >> index; | Declare variable. | C++ |
'result' + 25 | 'result' + str(25) | Can't add int to string. | Python |
console.log('world' | console.log('world') | Close parenthesis. | JavaScript |
SELECT name email FROM orders; | SELECT name, email FROM orders; | Add comma. | SQL |
<div><p>message</div></p> | <div><p>message</p></div> | Nest properly. | HTML |
if (foo) console.log('yes') else console.log('no') | if (foo) console.log('yes'); else console.log('no'); | Missing semicolon. | JavaScript |
{{"id":"world" "title":46}} | {{"id":"world", "title":46}} | Add comma. | JSON |
[58, 88, 5 | [58, 88, 5] | Close bracket. | Ruby |
object User {{ def main(args: Array[String]) = println("result") }} | object User {{ def main(args: Array[String]): Unit = println("result") }} | Add return type Unit. | Scala |
val bar = 'info' | val bar = "info" | Double quotes. | Kotlin |
render | render() | Add parentheses. | Kotlin |
var x = 17; | var x = 17; | Correct. | Dart |
arr[83] | if arr.indices.contains(83) {{ arr[83] }} | Check index. | Swift |
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