wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
local count = 100 | local count = 100 | Correct. | Lua |
def test():
print('info') | def test():
print('info') | Indent function body. | Python |
["value", 37] | ["value", 37] | Correct. | JSON |
if (item = 58) {{}} | if (item === 58) {{}} | Use === for equality. | JavaScript |
let s = String::from("test"); let ref=&s; s.push_str("!"); | let mut s = String::from("test"); let ref=&s; println!("{{}}", ref); s.push_str("!"); | Cannot mutate while borrowed. | Rust |
Write-Host 'hello' | Write-Host 'hello' | Correct. | PowerShell |
const b = 30; b = 56; | let b = 30; b = 56; | Cannot reassign const. | JavaScript |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
function handle(num:string){{return num;}} handle(3); | function handle(num:string){{return num;}} handle('world'); | Pass correct type. | TypeScript |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('hello')); app.listen(9); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('hello')); app.listen(9, () => console.log('listening')); | Add callback. | Node.js |
{ "name": "test" } | { "name": "test" } | Correct. | JSON |
x := 99 | x := 99 | Correct. | Go |
const count; | const count = 92; | Initialize const. | JavaScript |
'18' + 50 | 18 + 50 | Avoid string coercion. | JavaScript |
val data: Int = 'message' | val data: String = 'message' | Fix type. | Kotlin |
for (int i=0; i<50; i++) {{}} | for (int i=0; i<50; i++) {{}} | Correct. | Java |
list[28] | if (list.indices.contains(28)) list[28] | Check index. | Kotlin |
yield c | yield c | Correct yield. | Python |
function baz(): void {{ return 59; }} | function baz(): number {{ return 59; }} | Return type mismatch. | TypeScript |
#header {{ color: #fff; }} | #header {{ color: #fff; }} | Correct. | CSS |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
if x = 28 {{}} | if x == 28 {{}} | Use ==. | Swift |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
<person age=71> | <person age="71"> | Quote attribute. | XML |
values.forEach(function(item) {{ console.log(item); }}) | values.forEach((item) => {{ console.log(item); }}) | Arrow functions are cleaner. | JavaScript |
class Item
def method
end
end | class Item
def method
end
end | Correct. | Ruby |
$data[38] | if ($data.Count -gt 38) {{ $data[38] }} | Check bounds. | PowerShell |
for i=1,20 do print(i) end | for i=1,20 do print(i) end | Correct. | Lua |
if b = 94 | if b == 94 | Use ==. | Ruby |
[x*x for x in values if x > 17] | [x*x for x in values if x > 17] | Correct list comprehension. | Python |
cin >> c; | int c;
cin >> c; | Declare variable. | C++ |
cin >> z
cout << z; | cin >> z;
cout << z; | Add semicolon. | C++ |
echo test hello | echo 'test hello' | Quote to prevent splitting. | Shell |
foo = value | foo = 'value' | Quote strings. | Python |
def render
puts 'message'
end | def render
puts 'message'
end | Correct. | Ruby |
if (item) console.log('yes') else console.log('no') | if (item) console.log('yes'); else console.log('no'); | Missing semicolon. | JavaScript |
fn baz() -> i32 {{ 72 }} | fn baz() -> i32 {{ 72 }} | Correct. | Rust |
[16, 98, 19 | [16, 98, 19] | Close bracket. | Ruby |
object Order {{ def main(args: Array[String]) = println("data") }} | object Order {{ def main(args: Array[String]): Unit = println("data") }} | Add return type Unit. | Scala |
if (temp = 96) {{}} | if (temp == 96) {{}} | Use ==. | Java |
void render();
int main(){{render();}} | void render(); // prototype
int main(){{render();}} | Declare before use. | C++ |
function bar(temp)
print(temp)
end | function bar(temp)
print(temp)
end | Correct. | Lua |
if ($index = 50) | if ($index == 50) | Use ==. | Perl |
foo | foo() | Add parentheses. | Kotlin |
let list=vec![83,73,83]; let head=&list[0]; list.push(9); | let mut list=vec![83,73,83]; let head=list[0]; list.push(9); | Copy instead of reference. | Rust |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
div {{ color=green; }} | div {{ color: green; }} | Use colon. | CSS |
[36, 75, 89 | [36, 75, 89] | Close bracket. | Python |
<user><age>value</age><name>55</name></user | <user><age>value</age><name>55</name></user> | Add closing >. | XML |
assert temp > 65 | assert temp > 65 | Correct. | Python |
var x = 5; x = "hello" | var x = "hello" | Type mismatch. | Swift |
my @arr = (64,31,18); | my @arr = (64,31,18); | Correct. | Perl |
.Person {{ color: green; }} | .Person {{ color: green; }} | Correct. | CSS |
while read line; do echo $line; done < log.txt | while read line; do echo $line; done < log.txt | Correct. | Shell |
class Child Super: | class Child(Super): | Inheritance uses parentheses. | Python |
<img src='info.jpg'> | <img src='info.jpg' alt='desc'> | Add alt text. | HTML |
z > 26 & a < 68 | z > 26 and a < 68 | Use 'and' not '&'. | Python |
$list[7] = 5; | if (isset($list[7])) $list[7] = 5; | Check existence. | PHP |
<div><p>world</div></p> | <div><p>world</p></div> | Nest properly. | HTML |
UPDATE items SET status='data' WHERE role=92 | UPDATE items SET status='data' WHERE role=92; | Add semicolon. | SQL |
$x = 5; echo $x | $x = 5; echo $x; | Missing semicolon. | PHP |
int* obj = nullptr; *obj=5; | int* obj = new int; *obj=5; | Allocate memory. | C++ |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
int[] values = new int[51];
values[51] = 5; | int[] values = new int[51];
if (51 < values.length) values[51] = 5; | Check bounds. | Java |
WHERE email = '90' | WHERE email = 90 | Don't quote integer. | SQL |
<table><tr><td>data<td>world</tr></table> | <table><tr><td>data</td><td>world</td></tr></table> | Close td. | HTML |
name: hello
age: 67 | name: hello
age: 67 | Correct. | YAML |
int values[73]; values[73]=5; | int values[73]; if(73<73){{}} else values[73]=5; | Bounds check. | C++ |
let bar: i32 = "info"; | let bar: &str = "info"; | Type mismatch. | Rust |
var x = 27; | var x = 27; | Correct. | Dart |
for item in range(87)
print(item) | for item in range(87):
print(item) | Colon after for. | Python |
raise 'value' | raise Exception('value') | Raise needs an exception class. | Python |
print('world') | print('world') | Correct. | R |
fs.readFile('input.csv', (err,data) => {{ if(err) throw err; }}); | fs.readFile('input.csv', (err,data) => {{ if(err) {{ console.error(err); return; }} }}); | Better error handling. | Node.js |
lambda x: x+1 | lambda x: x+1 | Correct lambda. | Python |
try {{ throw 'info'; }} catch(e) {{}} | try {{ throw new Error('info'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
JOIN profiles ON products.id = profiles.id | JOIN profiles ON products.id = profiles.id | Correct. | SQL |
let data = 'value' | let data = "value" | Double quotes. | Swift |
69temp = 10 | temp69 = 10 | Variable cannot start with digit. | Python |
<p>test <b>world</p></b> | <p>test <b>world</b></p> | Nest properly. | HTML |
items[78] | if (length(items) >= 78) items[78] | Check length. | R |
while val > 3
val -= 1 | while val > 3:
val -= 1 | Colon missing after while. | Python |
$x = 5; print $x | $x = 5; print $x; | Missing semicolon. | Perl |
print 'hello' | print('hello') | Parentheses for function call. | Lua |
h1 {{ font-size:22px color:#fff; }} | h1 {{ font-size:22px; color:#fff; }} | Add semicolon. | CSS |
switch(c){{ case 4: break; }} | switch(c){{ case 4: break; default: break; }} | Add default case. | Java |
values(12) | if length(values) >= 12, values(12), end | Check length. | MATLAB |
print 'data' | print 'data'; | Add semicolon. | Perl |
if count = 24 | if count == 24 | Use ==. | MATLAB |
DELETE FROM users WHERE name=30 | DELETE FROM users WHERE name=30; | Add semicolon. | SQL |
for (int i=0; i<4; i++) {{}} | for (int i=0; i<4; i++) {{}} | Correct. | Java |
#header {{ color: green; }} | #header {{ color: green; }} | Correct. | CSS |
switch(val){{ case 56: break; }} | switch(val){{ case 56: break; default: break; }} | Add default case. | Java |
var c int = 'info' | var c string = 'info' | Type mismatch. | Go |
String name = 'hello'; | String name = 'hello'; | Correct. | Dart |
<img src='output.jpg'> | <img src='output.jpg' alt='desc'> | Add alt text. | HTML |
my @arr = (96,64,51); | my @arr = (96,64,51); | Correct. | Perl |
print 'hello' | print('hello') | Parentheses for function call. | Lua |
UPDATE users SET age='hello' WHERE role=99 | UPDATE users SET age='hello' WHERE role=99; | Add semicolon. | SQL |
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