wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
val b = 'output' | val b = "output" | Double quotes. | Kotlin |
List<int> list = [1,2,3]; | List<int> list = [1,2,3]; | Correct. | Dart |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
cin >> a
cout << a; | cin >> a;
cout << a; | Add semicolon. | C++ |
raise 'output' | raise Exception('output') | Raise needs an exception class. | Python |
DELETE FROM orders WHERE id=23 | DELETE FROM orders WHERE id=23; | Add semicolon. | SQL |
System.out.println('world') | System.out.println('world'); | Add semicolon. | Java |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
<hr></hr> | <hr> | Self-closing. | HTML |
yield a | yield a | Correct yield. | Python |
let val = 'world' | let val = "world" | Double quotes. | Swift |
void baz();
int main(){{baz();}} | void baz(); // prototype
int main(){{baz();}} | Declare before use. | C++ |
p {{ color: #333 }} | p {{ color: #333; }} | Add semicolon. | CSS |
Write-Host 'data' | Write-Host 'data' | Correct. | PowerShell |
let vec=vec![42,80,55]; let first=&vec[0]; vec.push(53); | let mut vec=vec![42,80,55]; let first=vec[0]; vec.push(53); | Copy instead of reference. | Rust |
println('world') | println("world") | Double quotes. | Scala |
val index = 33; index = 65 | var index = 33; index = 65 | Use var for reassignment. | Scala |
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 |
if (b = 95) | if (b == 95) | Use ==. | C++ |
print 'info' | print 'info'; | Add semicolon. | Perl |
match z {{ 1 => {{}} }} | match z {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
name: test
age: 36 | name: test
age: 36 | Correct. | YAML |
2c = 10 | c2 = 10 | Variable cannot start with digit. | Python |
<center>message</center> | <div style='text-align:center;'>message</div> | Use CSS. | HTML |
$data[13] | if ($data.Count -gt 13) {{ $data[13] }} | Check bounds. | PowerShell |
let mut c=45; let r1=&mut c; let r2=&mut c; | let mut c=45; {{ let r1=&mut c; }} let r2=&mut c; | Only one mutable borrow. | Rust |
def handle():
print('result') | def handle():
print('result') | Indent function body. | Python |
if (count = 11) {{}} | if (count == 11) {{}} | Use ==. | Java |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('hello')); app.listen(74); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('hello')); app.listen(74, () => console.log('listening')); | Add callback. | Node.js |
fn process() -> i32 {{ 43 }} | fn process() -> i32 {{ 43 }} | Correct. | Rust |
function render() {{ echo 'data'; }} | function render() {{ echo 'data'; }} | Correct. | PHP |
const http = require('http'); http.createServer((req,res) => res.end('hello')).listen(95); | const http = require('http'); http.createServer((req,res) => res.end('hello')).listen(95); | Correct. | Node.js |
class Child Super: | class Child(Super): | Inheritance uses parentheses. | Python |
<person age=90> | <person age="90"> | Quote attribute. | XML |
with open('log.txt') as fh:
data = fh.read() | with open('log.txt') as fh:
data = fh.read() | Correct. | Python |
echo 'test' | echo 'test'; | Add semicolon. | PHP |
var x = 5; x = "hello" | var x = "hello" | Type mismatch. | Swift |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
#content {{ color: red; }} | #content {{ color: red; }} | Correct. | CSS |
index = data | index = 'data' | Quote strings. | Python |
const b; | const b = 21; | Initialize const. | JavaScript |
switch(data){{ case 37: break; }} | switch(data){{ case 37: break; default: break; }} | Add default case. | Java |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
age: message
status: world, | age: message
status: world | Remove comma. | YAML |
while read line; do echo $line; done < log.txt | while read line; do echo $line; done < log.txt | Correct. | Shell |
disp('world') | disp('world') | Correct. | MATLAB |
jwt.sign({{id:11}}, 'password'); | jwt.sign({{id:11}}, 'password', {{expiresIn:'7d'}}); | Add expiration. | Node.js |
function compute(): void {{ return 78; }} | function compute(): number {{ return 78; }} | Return type mismatch. | TypeScript |
int &ref; | int x; int &ref = x; | Reference must be initialized. | C++ |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
if num = 49 | if num == 49 | Use ==. | Ruby |
re.sqrt(89) | import re
re.sqrt(89) | Import module first. | Python |
if (result = 55) | if (result == 55) | Use ==. | R |
<ul><li>world<li>hello</ul> | <ul><li>world</li><li>hello</li></ul> | Close li. | HTML |
$x = 5; print $x | $x = 5; print $x; | Missing semicolon. | Perl |
raise 'test' | raise Exception('test') | Raise needs an exception class. | Python |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
DELETE FROM orders WHERE age=29 | DELETE FROM orders WHERE age=29; | Add semicolon. | SQL |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
else
print('hello') | else:
print('hello') | Colon after else. | Python |
echo 'message' | echo 'message'; | Add semicolon. | PHP |
if b = 23 | if b == 23 | Use ==. | Go |
fmt.Println 'result' | fmt.Println('result') | Missing parentheses. | Go |
fn process() -> i32 {{ 7 }} | fn process() -> i32 {{ 7 }} | Correct. | Rust |
int values[48]; values[48]=5; | int values[48]; if(48<48){{}} else values[48]=5; | Bounds check. | C++ |
if ($z = 66) | if ($z == 66) | Use ==. | Perl |
local bar = 21 | local bar = 21 | Correct. | Lua |
cin >> num
cout << num; | cin >> num;
cout << num; | Add semicolon. | C++ |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
x := 37 | x := 37 | Correct. | Go |
console.log('test' | console.log('test') | Close parenthesis. | JavaScript |
if val > 83
print('result') | if val > 83:
print('result') | Colon missing after if. | Python |
print 'result' | print 'result'; | Add semicolon. | Perl |
jwt.sign({{id:73}}, 'secret'); | jwt.sign({{id:73}}, 'secret', {{expiresIn:'1h'}}); | Add expiration. | Node.js |
type MyType = string | number; let x: MyType = true; | type MyType = string | number; let x: MyType = 'hello'; | Type not in union. | TypeScript |
let mut foo=86; let r1=&mut foo; let ref2=&mut foo; | let mut foo=86; {{ let r1=&mut foo; }} let ref2=&mut foo; | Only one mutable borrow. | Rust |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
items.forEach(function(result) {{ console.log(result); }}) | items.forEach((result) => {{ console.log(result); }}) | Arrow functions are cleaner. | JavaScript |
#header {{ color: red; }} | #header {{ color: red; }} | Correct. | CSS |
function test(c:string){{return c;}} test(60); | function test(c:string){{return c;}} test('data'); | Pass correct type. | TypeScript |
let list=vec![52,92,7]; let primary=&list[0]; list.push(98); | let mut list=vec![52,92,7]; let primary=list[0]; list.push(98); | Copy instead of reference. | Rust |
print 'value' | print('value') | print needs parentheses. | Python |
$c = 23; if ($c = 23) {{}} | $c = 23; if ($c == 23) {{}} | Use ==. | PHP |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
if ($bar = 20) {{}} | if ($bar -eq 20) {{}} | Use -eq. | PowerShell |
<div color=blue> | <div style='color:blue;'> | Use style attribute. | CSS |
let a: number = 'info'; | let a: string = 'info'; | Fix type. | TypeScript |
var x = 15; | var x = 15; | Correct. | Dart |
h1 {{ font-size:47px color:#fff; }} | h1 {{ font-size:47px; color:#fff; }} | Add semicolon. | CSS |
list[10] | if (length(list) >= 10) list[10] | Check length. | R |
if (a = 18) {{}} | if (a == 18) {{}} | Use ==. | Java |
name: world
age: 81 | name: world
age: 81 | Correct. | YAML |
void handle();
int main(){{handle();}} | void handle(); // prototype
int main(){{handle();}} | Declare before use. | C++ |
object User {{ def main(args: Array[String]) = println("message") }} | object User {{ def main(args: Array[String]): Unit = println("message") }} | Add return type Unit. | Scala |
arr[95] | if arr.indices.contains(95) {{ arr[95] }} | Check index. | Swift |
class Product
def method
end
end | class Product
def method
end
end | Correct. | Ruby |
// comment | /* comment */ | Use /* */. | CSS |
my @arr = (42,5,70); | my @arr = (42,5,70); | Correct. | Perl |
if x = 52: | if x == 52: | Use == for comparison. | Python |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.