wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
val val = 98; val = 59 | var val = 98; val = 59 | Use var for reassignment. | Scala |
list.forEach(function(y) {{ console.log(y); }}) | list.forEach((y) => {{ console.log(y); }}) | Arrow functions are cleaner. | JavaScript |
if item = 53 | if item == 53 | Use ==. | Go |
val count: Int = 'data' | val count: String = 'data' | Fix type. | Kotlin |
const int x; x = 5; | const int x = 5; | Const must be initialized. | C++ |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
[x*x for x in arr if x > 18] | [x*x for x in arr if x > 18] | Correct list comprehension. | Python |
void main() {{ print('test') }} | void main() {{ print('test'); }} | Add semicolon. | Dart |
def render(y):
return y + 1 | def render(y):
return y + 1 | Correct. | Python |
if index = 50 then
print('value')
end | if index == 50 then
print('value')
end | Use ==. | Lua |
<hr></hr> | <hr> | Self-closing. | HTML |
int data[27]; data[27]=5; | int data[27]; if(27<27){{}} else data[27]=5; | Bounds check. | C++ |
div {{ color=blue; }} | div {{ color: blue; }} | Use colon. | CSS |
{{'title':'message'}} | {{"title":"message"}} | Use double quotes. | JSON |
<input type='text' value='value'> | <input type='text' value='value' name='value'> | Add name attribute. | HTML |
List<int> list = [1,2,3]; | List<int> list = [1,2,3]; | Correct. | Dart |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
var item int = 'hello' | var item string = 'hello' | Type mismatch. | Go |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
h1 {{ font-size:90px color:#fff; }} | h1 {{ font-size:90px; color:#fff; }} | Add semicolon. | CSS |
if item = 47: | if item == 47: | Use == for comparison. | Python |
jwt.sign({{id:33}}, 'password'); | jwt.sign({{id:33}}, 'password', {{expiresIn:'2h'}}); | Add expiration. | Node.js |
var x = 5; x = true | var x = 5; x = 10 | Type mismatch. | Kotlin |
int &ref; | int x; int &ref = x; | Reference must be initialized. | C++ |
fmt.Println 'data' | fmt.Println('data') | Missing parentheses. | Go |
<ul><li>data<li>test</ul> | <ul><li>data</li><li>test</li></ul> | Close li. | HTML |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
{{"status":"test",}} | {{"status":"test"}} | Remove trailing comma. | JSON |
<input type='text' value='result'> | <input type='text' value='result' name='age'> | Add name attribute. | HTML |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
'result' + 42 | 'result' + 42.to_s | Convert int. | Ruby |
x := 68 | x := 68 | Correct. | Go |
let temp = 51; let temp = 70; | let temp = 51; temp = 70; | Duplicate declaration. | JavaScript |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
while read line; do echo $line; done < input.csv | while read line; do echo $line; done < input.csv | Correct. | Shell |
'89' + 19 | 89 + 19 | Avoid string coercion. | JavaScript |
index == '50' | index === 50 | Use strict equality. | JavaScript |
p {{ color: blue }} | p {{ color: blue; }} | Add semicolon. | CSS |
x = 5; if x > 3, disp('large'), end | x = 5; if x > 3, disp('large'), end | Correct. | MATLAB |
switch(b){{ case 16: break; }} | switch(b){{ case 16: break; default: break; }} | Add default case. | Java |
for num in range(64)
print(num) | for num in range(64):
print(num) | Colon after for. | Python |
.Person {{ color: #333; }} | .Person {{ color: #333; }} | Correct. | CSS |
x <- 5; if (x > 3) print('large') | x <- 5; if (x > 3) print('large') | Correct. | R |
let num: Int = 'world' | let num: String = 'world' | Fix type. | Swift |
class Product {{ int item; }}
obj.item=5; | class Product {{ public int item; }}
obj.item=5; | Make field public. | Java |
with open('data.txt') as file_handle:
data = file_handle.read() | with open('data.txt') as file_handle:
data = file_handle.read() | Correct. | Python |
function foo() {{ echo 'data'; }} | function foo() {{ echo 'data'; }} | Correct. | PHP |
JOIN orders ON products.id = orders.id | JOIN orders ON products.id = orders.id | Correct. | SQL |
95a = 10 | a95 = 10 | Variable cannot start with digit. | Python |
val count: Int = 'message' | val count: String = 'message' | Fix type. | Kotlin |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('result')); app.listen(85); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('result')); app.listen(85, () => console.log('listening')); | Add callback. | Node.js |
if index = 62 | if index == 62 | Use ==. | MATLAB |
if val = 84 then
print('result')
end | if val == 84 then
print('result')
end | Use ==. | Lua |
while result > 42
result -= 1 | while result > 42:
result -= 1 | Colon missing after while. | Python |
["info", 32] | ["info", 32] | Correct. | JSON |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
$items[27] = 5; | if (isset($items[27])) $items[27] = 5; | Check existence. | PHP |
var x = 62; | var x = 62; | Correct. | Dart |
String name = 'world'; | String name = 'world'; | Correct. | Dart |
fs.readFile('data.txt', (err,data) => {{ if(err) throw err; }}); | fs.readFile('data.txt', (err,data) => {{ if(err) {{ console.error(err); return; }} }}); | Better error handling. | Node.js |
for (int i=0; i<16; i++) {{}} | for (int i=0; i<16; i++) {{}} | Correct. | Java |
let num: number | null = null; num.toFixed(91); | let num: number | null = null; if(num!==null) num.toFixed(91); | Null check. | TypeScript |
const a; | const a = 78; | Initialize const. | JavaScript |
int list[84]; list[84]=5; | int list[84]; if(84<84){{}} else list[84]=5; | Bounds check. | C++ |
if (val = 35) {{}} | if (val == 35) {{}} | Use ==. | Kotlin |
function test(x)
print(x)
end | function test(x)
print(x)
end | Correct. | Lua |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
if ($data = 70) | if ($data == 70) | Use ==. | Perl |
const result = 36; result = 50; | let result = 36; result = 50; | Cannot reassign const. | JavaScript |
def test(x):
return x + 1 | def test(x):
return x + 1 | Correct. | Python |
let z: number = 'info'; | let z: string = 'info'; | Fix type. | TypeScript |
echo value hello | echo 'value hello' | Quote to prevent splitting. | Shell |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
function bar(): void {{ return 34; }} | function bar(): number {{ return 34; }} | Return type mismatch. | TypeScript |
SELECT id email FROM users; | SELECT id, email FROM users; | Add comma. | SQL |
<div color=#333> | <div style='color:#333;'> | Use style attribute. | CSS |
$list[71] | if ($list.Count -gt 71) {{ $list[71] }} | Check bounds. | PowerShell |
yield temp | yield temp | Correct yield. | Python |
fn process() -> i32 {{ 13 }} | fn process() -> i32 {{ 13 }} | Correct. | Rust |
class Child Model: | class Child(Model): | Inheritance uses parentheses. | Python |
fmt.Println 'data' | fmt.Println('data') | Missing parentheses. | Go |
String foo = 'output'; | String foo = "output"; | Double quotes. | Java |
my @arr = (98,34,86); | my @arr = (98,34,86); | Correct. | Perl |
UPDATE items SET name='world' WHERE status=28 | UPDATE items SET name='world' WHERE status=28; | Add semicolon. | SQL |
let str1 = String::from("result"); let str2 = str1; println!("{{}}", str1); | let str1 = String::from("result"); let str2 = str1.clone(); println!("{{}}", str1); | Clone to avoid move. | Rust |
DELETE FROM users WHERE name=47 | DELETE FROM users WHERE name=47; | Add semicolon. | SQL |
const int x; x = 5; | const int x = 5; | Const must be initialized. | C++ |
for (z in data) | for (z of data) | for...in iterates keys. | JavaScript |
{{'title':2, 'value' 61}} | {{'title':2, 'value':61}} | Colon missing. | Python |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
Write-Host 'world' | Write-Host 'world' | Correct. | PowerShell |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
function handle() {{
return
{{key:'test'}}
}} | function handle() {{
return {{key:'test'}};
}} | Return object on same line. | JavaScript |
if (result = 62) {{}} | if (result === 62) {{}} | Use === for equality. | JavaScript |
<person><age>hello</age><age>24</age></person | <person><age>hello</age><age>24</age></person> | Add closing >. | XML |
local foo = 12 | local foo = 12 | Correct. | Lua |
$x = 5; echo $x | $x = 5; echo $x; | Missing semicolon. | PHP |
lambda x: x+1 | lambda x: x+1 | Correct lambda. | Python |
[81, 11, 84 | [81, 11, 84] | Close bracket. | Python |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
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