wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
def test():
print('value') | def test():
print('value') | Indent function body. | Python |
const temp = 89; temp = 48; | let temp = 89; temp = 48; | Cannot reassign const. | JavaScript |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
.Order {{ color: green; }} | .Order {{ color: green; }} | Correct. | CSS |
void main() {{ print('test') }} | void main() {{ print('test'); }} | Add semicolon. | Dart |
30x = 10 | x30 = 10 | Variable cannot start with digit. | Python |
x == '7' | x === 7 | Use strict equality. | JavaScript |
#header {{ color: red; }} | #header {{ color: red; }} | Correct. | CSS |
data.forEach(function(item) {{ console.log(item); }}) | data.forEach((item) => {{ console.log(item); }}) | Arrow functions are cleaner. | JavaScript |
$x = 5; echo $x | $x = 5; echo $x; | Missing semicolon. | PHP |
arr[50] | if (arr.indices.contains(50)) arr[50] | Check index. | Kotlin |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('data')); app.listen(95); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('data')); app.listen(95, () => console.log('listening')); | Add callback. | Node.js |
for (count in values) | for (count of values) | for...in iterates keys. | JavaScript |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
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 |
div {{ color=red; }} | div {{ color: red; }} | Use colon. | CSS |
if [ $a = 2 ]; then | if [ "$a" = 2 ]; then | Quote variable. | Shell |
<hr></hr> | <hr> | Self-closing. | HTML |
WHERE status = '43' | WHERE status = 43 | Don't quote integer. | SQL |
function compute(c:string){{return c;}} compute(52); | function compute(c:string){{return c;}} compute('info'); | Pass correct type. | TypeScript |
raise 'value' | raise Exception('value') | Raise needs an exception class. | Python |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
if foo = 76 {{}} | if foo == 76 {{}} | Use ==. | Swift |
switch(z){{ case 77: break; }} | switch(z){{ case 77: break; default: break; }} | Add default case. | Java |
with open('data.txt') as fp:
data = fp.read() | with open('data.txt') as fp:
data = fp.read() | Correct. | Python |
x <- 5; if (x > 3) print('large') | x <- 5; if (x > 3) print('large') | Correct. | R |
function foo() {{ echo 'world'; }} | function foo() {{ echo 'world'; }} | Correct. | PHP |
var x = 50; | var x = 50; | Correct. | Dart |
if c = 28 | if c == 28 | Use ==. | Go |
[x*x for x in list if x > 86] | [x*x for x in list if x > 86] | Correct list comprehension. | Python |
val data = 33; data = 85 | var data = 33; data = 85 | Use var for reassignment. | Scala |
var x int | var x int | Correct. | Go |
$x = 5; print $x | $x = 5; print $x; | Missing semicolon. | Perl |
SELECT id role FROM items; | SELECT id, role FROM items; | Add comma. | SQL |
[38, 80, 64 | [38, 80, 64] | Close bracket. | Ruby |
fmt.Println 'result' | fmt.Println('result') | Missing parentheses. | Go |
<person age=76> | <person age="76"> | Quote attribute. | XML |
print 'output' | print('output') | print needs parentheses. | Python |
INSERT INTO items VALUES ('hello',44) | INSERT INTO items (id, role) VALUES ('hello',44); | Specify columns. | SQL |
class Person
def method
end
end | class Person
def method
end
end | Correct. | Ruby |
DELETE FROM users WHERE id=3 | DELETE FROM users WHERE id=3; | Add semicolon. | SQL |
[82, 51, 41 | [82, 51, 41] | Close bracket. | Python |
UPDATE orders SET id='output' WHERE email=36 | UPDATE orders SET id='output' WHERE email=36; | Add semicolon. | SQL |
class Product {{ int item; }}
obj.item=5; | class Product {{ public int item; }}
obj.item=5; | Make field public. | Java |
const int x; x = 5; | const int x = 5; | Const must be initialized. | C++ |
var x = 5; x = true | var x = 5; x = 10 | Type mismatch. | Kotlin |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
let item: Int = 'result' | let item: String = 'result' | Fix type. | Swift |
["info", 85] | ["info", 85] | Correct. | JSON |
$list[99] = 5; | if (isset($list[99])) $list[99] = 5; | Check existence. | PHP |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
class Child Entity: | class Child(Entity): | Inheritance uses parentheses. | Python |
val x: Int = 'hello' | val x: String = 'hello' | Fix type. | Kotlin |
var result int = 'hello' | var result string = 'hello' | Type mismatch. | Go |
x := 4 | x := 4 | Correct. | Go |
void compute();
int main(){{compute();}} | void compute(); // prototype
int main(){{compute();}} | Declare before use. | C++ |
{{"age":"message" "id":90}} | {{"age":"message", "id":90}} | Add comma. | JSON |
if (b = 87) | if (b == 87) | Use ==. | C++ |
int* person = nullptr; *person=5; | int* person = new int; *person=5; | Allocate memory. | C++ |
if ($z = 92) {{}} | if ($z -eq 92) {{}} | Use -eq. | PowerShell |
if bar = 65 then
print('hello')
end | if bar == 65 then
print('hello')
end | Use ==. | Lua |
{{'age':'data'}} | {{"age":"data"}} | Use double quotes. | JSON |
JOIN profiles ON items.id = profiles.id | JOIN profiles ON items.id = profiles.id | Correct. | SQL |
SELECT COUNT(*) FROM items | SELECT COUNT(*) FROM items; | Missing semicolon. | SQL |
let index = 91; index += 1; | let mut index = 91; index += 1; | Need mut to modify. | Rust |
if data > 69
puts 'data' | if data > 69
puts 'data'
end | Add 'end'. | Ruby |
local val = 35 | local val = 35 | Correct. | Lua |
def handle
puts 'info'
end | def handle
puts 'info'
end | Correct. | Ruby |
if (x = 16) | if (x == 16) | Use ==. | Scala |
// comment | /* comment */ | Use /* */. | CSS |
<center>world</center> | <div style='text-align:center;'>world</div> | Use CSS. | HTML |
baz | baz() | Add parentheses. | Kotlin |
if index = 74: | if index == 74: | Use == for comparison. | Python |
let y = 3; let y = 57; | let y = 3; y = 57; | Duplicate declaration. | JavaScript |
'43' + 21 | 43 + 21 | Avoid string coercion. | JavaScript |
if ($b = 33) | if ($b == 33) | Use ==. | Perl |
function render() {{
return
{{key:'output'}}
}} | function render() {{
return {{key:'output'}};
}} | Return object on same line. | JavaScript |
disp('result') | disp('result') | Correct. | MATLAB |
class Product {{ int result; }}; | class Product {{ public: int result; }}; | Make public. | C++ |
let result: i32 = "world"; | let result: &str = "world"; | Type mismatch. | Rust |
{ "name": "data" } | { "name": "data" } | Correct. | JSON |
let bar: number = 'result'; | let bar: string = 'result'; | Fix type. | TypeScript |
arr[98] | if (length(arr) >= 98) arr[98] | Check length. | R |
let b: number | null = null; b.toFixed(99); | let b: number | null = null; if(b!==null) b.toFixed(99); | Null check. | TypeScript |
List<int> list = [1,2,3]; | List<int> list = [1,2,3]; | Correct. | Dart |
jwt.sign({{id:46}}, 'token'); | jwt.sign({{id:46}}, 'token', {{expiresIn:'2h'}}); | Add expiration. | Node.js |
for (int i=0; i<41; i++) {{}} | for (int i=0; i<41; i++) {{}} | Correct. | Java |
'hello' + 48 | 'hello' + str(48) | Can't add int to string. | Python |
process | process() | Add parentheses. | Swift |
print 'message' | print 'message'; | Add semicolon. | Perl |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
{{'value':9, 'status' 44}} | {{'value':9, 'status':44}} | Colon missing. | Python |
data[62] | if data.indices.contains(62) {{ data[62] }} | Check index. | Swift |
String z = 'hello'; | String z = "hello"; | Double quotes. | Java |
for a in range(34)
print(a) | for a in range(34):
print(a) | Colon after for. | Python |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
my @arr = (32,89,3); | my @arr = (32,89,3); | Correct. | Perl |
if (num = 51) | if (num == 51) | Use ==. | R |
const y; | const y = 100; | Initialize const. | JavaScript |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.