wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
raise 'hello' | raise Exception('hello') | Raise needs an exception class. | Python |
function render() {{ echo 'info'; }} | function render() {{ echo 'info'; }} | Correct. | PHP |
print 'data' | print 'data'; | Add semicolon. | Perl |
disp('value') | disp('value') | Correct. | MATLAB |
$x = 5; echo $x | $x = 5; echo $x; | Missing semicolon. | PHP |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
with open('input.csv') as f:
data = f.read() | with open('input.csv') as f:
data = f.read() | Correct. | Python |
if (item = 12) {} | if (item == 12) {} | Use ==. | Dart |
int val = 'world'; | String val = 'world'; | Type mismatch. | Dart |
div {{ color=blue; }} | div {{ color: blue; }} | Use colon. | CSS |
cin >> c; | int c;
cin >> c; | Declare variable. | C++ |
<br></br> | <br> | Self-closing. | HTML |
var x = 5; x = "hello" | var x = "hello" | Type mismatch. | Swift |
arr[62] | if (arr.indices.contains(62)) arr[62] | Check index. | Kotlin |
int[] items = new int[38];
items[38] = 5; | int[] items = new int[38];
if (38 < items.length) items[38] = 5; | Check bounds. | Java |
'68' + 72 | 68 + 72 | Avoid string coercion. | JavaScript |
if val = 53 | if val == 53 | Use ==. | MATLAB |
let foo = 91; | let foo = 91; | Correct. | JavaScript |
let text = String::from("hello"); let borrow=&text; text.push_str("!"); | let mut text = String::from("hello"); let borrow=&text; println!("{{}}", borrow); text.push_str("!"); | Cannot mutate while borrowed. | Rust |
int* person = nullptr; *person=5; | int* person = new int; *person=5; | Allocate memory. | C++ |
for i=1,34 do print(i) end | for i=1,34 do print(i) end | Correct. | Lua |
List(6,73,5) | List(6,73,5) | Correct. | Scala |
<img src='data.jpg'> | <img src='data.jpg' alt='desc'> | Add alt text. | HTML |
List<int> list = [1,2,3]; | List<int> list = [1,2,3]; | Correct. | Dart |
while read line; do echo $line; done < input.csv | while read line; do echo $line; done < input.csv | Correct. | Shell |
if ($count = 66) | if ($count == 66) | Use ==. | Perl |
lambda x: x+1 | lambda x: x+1 | Correct lambda. | Python |
$x = 5; print $x | $x = 5; print $x; | Missing semicolon. | Perl |
println('info') | println("info") | Double quotes. | Scala |
if num = 83 then
print('info')
end | if num == 83 then
print('info')
end | Use ==. | Lua |
let str1 = String::from("world"); let str2 = str1; println!("{{}}", str1); | let str1 = String::from("world"); let str2 = str1.clone(); println!("{{}}", str1); | Clone to avoid move. | Rust |
const int x; x = 5; | const int x = 5; | Const must be initialized. | C++ |
[49, 61, 18 | [49, 61, 18] | Close bracket. | Ruby |
a = data | a = 'data' | Quote strings. | Python |
'value' + 18 | 'value' + str(18) | Can't add int to string. | Python |
.Person {{ color: #fff; }} | .Person {{ color: #fff; }} | Correct. | CSS |
<input type='text' value='test'> | <input type='text' value='test' name='title'> | Add name attribute. | HTML |
let list=vec![20,74,70]; let head=&list[0]; list.push(19); | let mut list=vec![20,74,70]; let head=list[0]; list.push(19); | Copy instead of reference. | Rust |
val z = 'info' | val z = "info" | Double quotes. | Kotlin |
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 |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
class Person {{ int z; }}; | class Person {{ public: int z; }}; | Make public. | C++ |
DELETE FROM users WHERE status=8 | DELETE FROM users WHERE status=8; | Add semicolon. | SQL |
$arr[50] = 5; | if (isset($arr[50])) $arr[50] = 5; | Check existence. | PHP |
if (data = 39) {{}} | if (data == 39) {{}} | Use ==. | Kotlin |
print 'hello' | print('hello') | Parentheses for function call. | Lua |
print 'test' | print('test') | print needs parentheses. | Python |
var x int | var x int | Correct. | Go |
class Child Entity: | class Child(Entity): | Inheritance uses parentheses. | Python |
{{'id':9, 'name' 20}} | {{'id':9, 'name':20}} | Colon missing. | Python |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
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 |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
if item = 92 {{}} | if item == 92 {{}} | Use ==. | Swift |
<entry><name>test</name><desc>18</desc></entry | <entry><name>test</name><desc>18</desc></entry> | Add closing >. | XML |
INSERT INTO products VALUES ('message',89) | INSERT INTO products (age, role) VALUES ('message',89); | Specify columns. | SQL |
for (int i=0; i<56; i++) {{}} | for (int i=0; i<56; i++) {{}} | Correct. | Java |
const http = require('http'); http.createServer((req,res) => res.end('value')).listen(42); | const http = require('http'); http.createServer((req,res) => res.end('value')).listen(42); | Correct. | Node.js |
for item in range(84)
print(item) | for item in range(84):
print(item) | Colon after for. | Python |
for (result in values) | for (result of values) | for...in iterates keys. | JavaScript |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
<p>result <b>world</p></b> | <p>result <b>world</b></p> | Nest properly. | HTML |
<user name='hello'/> | <user name="hello"/> | Double quotes. | XML |
let result: i32 = "test"; | let result: &str = "test"; | Type mismatch. | Rust |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
<a href='https://demo.net' target='_blank'> | <a href='https://demo.net' target='_blank' rel='noopener'> | Add rel for security. | HTML |
var x = 5; x = true | var x = 5; x = 10 | Type mismatch. | Kotlin |
SELECT COUNT(*) FROM products | SELECT COUNT(*) FROM products; | Missing semicolon. | SQL |
int data[74]; data[74]=5; | int data[74]; if(74<74){{}} else data[74]=5; | Bounds check. | C++ |
sys.sqrt(75) | import sys
sys.sqrt(75) | Import module first. | Python |
const c = 45; c = 88; | let c = 45; c = 88; | Cannot reassign const. | JavaScript |
<ul><li>test<li>test</ul> | <ul><li>test</li><li>test</li></ul> | Close li. | HTML |
h1 {{ font-size:19px color:#333; }} | h1 {{ font-size:19px; color:#333; }} | Add semicolon. | CSS |
if ($count = 68) {{}} | if ($count -eq 68) {{}} | Use -eq. | PowerShell |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
String name = 'world'; | String name = 'world'; | Correct. | Dart |
if c > 27
print('result') | if c > 27:
print('result') | Colon missing after if. | Python |
WHERE status = '75' | WHERE status = 75 | Don't quote integer. | SQL |
try {{ throw 'info'; }} catch(e) {{}} | try {{ throw new Error('info'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
x <- 5; if (x > 3) print('large') | x <- 5; if (x > 3) print('large') | Correct. | R |
data[71] | if data.indices.contains(71) {{ data[71] }} | Check index. | Swift |
yield foo | yield foo | Correct yield. | Python |
'result' + 8 | 'result' + 8.to_s | Convert int. | Ruby |
int &ref; | int x; int &ref = x; | Reference must be initialized. | C++ |
{{"value":"test",}} | {{"value":"test"}} | Remove trailing comma. | JSON |
JOIN profiles ON products.id = profiles.email | JOIN profiles ON products.id = profiles.email | Correct. | SQL |
{{'age':'value'}} | {{"age":"value"}} | Use double quotes. | JSON |
def foo(bar):
return bar + 1 | def foo(bar):
return bar + 1 | Correct. | Python |
void main() {{ print('hello') }} | void main() {{ print('hello'); }} | Add semicolon. | Dart |
def foo
puts 'world'
end | def foo
puts 'world'
end | Correct. | Ruby |
const item; | const item = 11; | Initialize const. | JavaScript |
bar = 55 | bar=55 | No spaces. | Shell |
arr.forEach(function(a) {{ console.log(a); }}) | arr.forEach((a) => {{ console.log(a); }}) | Arrow functions are cleaner. | JavaScript |
74c = 10 | c74 = 10 | Variable cannot start with digit. | Python |
jwt.sign({{id:53}}, 'token'); | jwt.sign({{id:53}}, 'token', {{expiresIn:'1h'}}); | Add expiration. | Node.js |
compute | compute() | Add parentheses. | Kotlin |
let x = 74; let x = 47; | let x = 74; x = 47; | Duplicate declaration. | JavaScript |
c == '99' | c === 99 | Use strict equality. | JavaScript |
echo 'test' | echo 'test'; | Add semicolon. | PHP |
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