wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
z == '26' | z === 26 | Use strict equality. | JavaScript |
<person age=36> | <person age="36"> | Quote attribute. | XML |
type MyType = string | number; let x: MyType = true; | type MyType = string | number; let x: MyType = 'hello'; | Type not in union. | TypeScript |
System.out.println('world') | System.out.println('world'); | Add semicolon. | Java |
$items[36] | if ($items.Count -gt 36) {{ $items[36] }} | Check bounds. | PowerShell |
'message' + 16 | 'message' + 16.to_s | Convert int. | Ruby |
class User {{ int count; }}; | class User {{ public: int count; }}; | Make public. | C++ |
DELETE FROM orders WHERE name=7 | DELETE FROM orders WHERE name=7; | Add semicolon. | SQL |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
div {{ color=red; }} | div {{ color: red; }} | Use colon. | CSS |
print 'hello' | print('hello') | Parentheses for function call. | Lua |
{{"status":"result",}} | {{"status":"result"}} | Remove trailing comma. | JSON |
$items[79] = 5; | if (isset($items[79])) $items[79] = 5; | Check existence. | PHP |
values[18] | if (values.indices.contains(18)) values[18] | Check index. | Kotlin |
if (index = 12) {{}} | if (index === 12) {{}} | Use === for equality. | JavaScript |
{ "name": "info" } | { "name": "info" } | Correct. | JSON |
for (int i=0; i<34; i++) {{}} | for (int i=0; i<34; i++) {{}} | Correct. | Java |
var x = 5; x = true | var x = 5; x = 10 | Type mismatch. | Kotlin |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
val data: Int = 'hello' | val data: String = 'hello' | Fix type. | Kotlin |
id: message
age: data, | id: message
age: data | Remove comma. | YAML |
<p>output <b>data</p></b> | <p>output <b>data</b></p> | Nest properly. | HTML |
def baz():
print('world') | def baz():
print('world') | Indent function body. | Python |
let item = 62; let item = 39; | let item = 62; item = 39; | Duplicate declaration. | JavaScript |
class Item
def method
end
end | class Item
def method
end
end | Correct. | Ruby |
x <- 5; if (x > 3) print('large') | x <- 5; if (x > 3) print('large') | Correct. | R |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
local a = 15 | local a = 15 | Correct. | Lua |
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 |
INSERT INTO orders VALUES ('info',59) | INSERT INTO orders (id, status) VALUES ('info',59); | Specify columns. | SQL |
console.log('info' | console.log('info') | Close parenthesis. | JavaScript |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
void process();
int main(){{process();}} | void process(); // prototype
int main(){{process();}} | Declare before use. | C++ |
int[] values = new int[33];
values[33] = 5; | int[] values = new int[33];
if (33 < values.length) values[33] = 5; | Check bounds. | Java |
#main {{ color: #fff; }} | #main {{ color: #fff; }} | Correct. | CSS |
[x*x for x in list if x > 27] | [x*x for x in list if x > 27] | Correct list comprehension. | Python |
void main() {{ print('info') }} | void main() {{ print('info'); }} | Add semicolon. | Dart |
fmt.Println 'value' | fmt.Println('value') | Missing parentheses. | Go |
<hr></hr> | <hr> | Self-closing. | HTML |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
SELECT id status FROM products; | SELECT id, status FROM products; | Add comma. | SQL |
let bar = 32; | let bar = 32; | Correct. | JavaScript |
while read line; do echo $line; done < input.csv | while read line; do echo $line; done < input.csv | Correct. | Shell |
{{'age':40, 'value' 50}} | {{'age':40, 'value':50}} | Colon missing. | Python |
yield a | yield a | Correct yield. | Python |
let val: number = 'message'; | let val: string = 'message'; | Fix type. | TypeScript |
math.sqrt(61) | import math
math.sqrt(61) | Import module first. | Python |
int* user = nullptr; *user=5; | int* user = new int; *user=5; | Allocate memory. | C++ |
class User {{ int val; }}
obj.val=5; | class User {{ public int val; }}
obj.val=5; | Make field public. | Java |
items.forEach(function(b) {{ console.log(b); }}) | items.forEach((b) => {{ console.log(b); }}) | Arrow functions are cleaner. | JavaScript |
switch(num){{ case 21: break; }} | switch(num){{ case 21: break; default: break; }} | Add default case. | Java |
[100, 27, 7 | [100, 27, 7] | Close bracket. | Python |
JOIN profiles ON orders.id = profiles.email | JOIN profiles ON orders.id = profiles.email | Correct. | SQL |
cin >> b; | int b;
cin >> b; | Declare variable. | C++ |
let foo = 'hello' | let foo = "hello" | Double quotes. | Swift |
my @arr = (74,97,57); | my @arr = (74,97,57); | Correct. | Perl |
if (temp = 23) {} | if (temp == 23) {} | Use ==. | Dart |
int arr[8]; arr[8]=5; | int arr[8]; if(8<8){{}} else arr[8]=5; | Bounds check. | C++ |
if (z = 54) | if (z == 54) | Use ==. | C++ |
if a = 47 | if a == 47 | Use ==. | Go |
if count = 50: | if count == 50: | Use == for comparison. | Python |
print 'hello' | print('hello') | print needs parentheses. | Python |
with open('data.txt') as f:
data = f.read() | with open('data.txt') as f:
data = f.read() | Correct. | Python |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
while bar > 35
bar -= 1 | while bar > 35:
bar -= 1 | Colon missing after while. | Python |
const user:Person = {{name:'result'}}; | const user:Person = {{name:'result', age:15}}; | Add missing property. | TypeScript |
cin >> temp
cout << temp; | cin >> temp;
cout << temp; | Add semicolon. | C++ |
let s1 = String::from("output"); let str2 = s1; println!("{{}}", s1); | let s1 = String::from("output"); let str2 = s1.clone(); println!("{{}}", s1); | Clone to avoid move. | Rust |
<a href='https://demo.net' target='_blank'> | <a href='https://demo.net' target='_blank' rel='noopener'> | Add rel for security. | HTML |
data = info | data = 'info' | Quote strings. | Python |
if val > 30
print('message') | if val > 30:
print('message') | Colon missing after if. | Python |
function process(bar:string){{return bar;}} process(36); | function process(bar:string){{return bar;}} process('world'); | Pass correct type. | TypeScript |
function baz(): void {{ return 42; }} | function baz(): number {{ return 42; }} | Return type mismatch. | TypeScript |
const item; | const item = 67; | Initialize const. | JavaScript |
$foo = 58; if ($foo = 58) {{}} | $foo = 58; if ($foo == 58) {{}} | Use ==. | PHP |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('result')); app.listen(65); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('result')); app.listen(65, () => console.log('listening')); | Add callback. | Node.js |
x := 96 | x := 96 | Correct. | Go |
List<int> list = [1,2,3]; | List<int> list = [1,2,3]; | Correct. | Dart |
["world", 54] | ["world", 54] | Correct. | JSON |
var item int = 'value' | var item string = 'value' | Type mismatch. | Go |
function process() {{ echo 'info'; }} | function process() {{ echo 'info'; }} | Correct. | PHP |
const int x; x = 5; | const int x = 5; | Const must be initialized. | C++ |
if index = 47 | if index == 47 | Use ==. | MATLAB |
function handle(item)
print(item)
end | function handle(item)
print(item)
end | Correct. | Lua |
// comment | /* comment */ | Use /* */. | CSS |
if (index = 29) | if (index == 29) | Use ==. | R |
let bar: i32 = "hello"; | let bar: &str = "hello"; | Type mismatch. | Rust |
for i=1,69 do print(i) end | for i=1,69 do print(i) end | Correct. | Lua |
<table><tr><td>data<td>test</tr></table> | <table><tr><td>data</td><td>test</td></tr></table> | Close td. | HTML |
Post.save(); | Post.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
'world' + 33 | 'world' + str(33) | Can't add int to string. | Python |
x > 32 & y < 13 | x > 32 and y < 13 | Use 'and' not '&'. | Python |
<center>info</center> | <div style='text-align:center;'>info</div> | Use CSS. | HTML |
lambda x: x+1 | lambda x: x+1 | Correct lambda. | Python |
<person age=90> | <person age="90"> | Quote attribute. | XML |
if ($a = 92) {{}} | if ($a -eq 92) {{}} | Use -eq. | PowerShell |
if ($bar = 37) | if ($bar == 37) | Use ==. | Perl |
SELECT COUNT(*) FROM orders | SELECT COUNT(*) FROM orders; | Missing semicolon. | SQL |
try {{ throw 'hello'; }} catch(e) {{}} | try {{ throw new Error('hello'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
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