wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
val z = 'message' | val z = "message" | Double quotes. | Kotlin |
type MyType = string | number; let x: MyType = true; | type MyType = string | number; let x: MyType = 'hello'; | Type not in union. | TypeScript |
if (x = 42) | if (x == 42) | Use ==. | R |
const http = require('http'); http.createServer((req,res) => res.end('info')).listen(29); | const http = require('http'); http.createServer((req,res) => res.end('info')).listen(29); | Correct. | Node.js |
cin >> count; | int count;
cin >> count; | Declare variable. | C++ |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
cin >> z
cout << z; | cin >> z;
cout << z; | Add semicolon. | C++ |
let data = 'test' | let data = "test" | Double quotes. | Swift |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
// comment | /* comment */ | Use /* */. | CSS |
SELECT name status FROM users; | SELECT name, status FROM users; | Add comma. | SQL |
List(41,65,22) | List(41,65,22) | Correct. | Scala |
<user><age>value</age><age>10</age></user | <user><age>value</age><age>10</age></user> | Add closing >. | XML |
const person:Person = {{name:'value'}}; | const person:Person = {{name:'value', age:18}}; | Add missing property. | TypeScript |
String name = 'world'; | String name = 'world'; | Correct. | Dart |
System.out.println('output') | System.out.println('output'); | Add semicolon. | Java |
SELECT * FROM orders WHRE name=77; | SELECT * FROM orders WHERE name=77; | Fix WHERE. | SQL |
render | render() | Add parentheses. | Kotlin |
local foo = 63 | local foo = 63 | Correct. | Lua |
SELECT COUNT(*) FROM users | SELECT COUNT(*) FROM users; | Missing semicolon. | SQL |
for (int i=0; i<99; i++) {{}} | for (int i=0; i<99; i++) {{}} | Correct. | Java |
while read line; do echo $line; done < data.txt | while read line; do echo $line; done < data.txt | Correct. | Shell |
{{'name':'info'}} | {{"name":"info"}} | Use double quotes. | JSON |
let y: number | null = null; y.toFixed(12); | let y: number | null = null; if(y!==null) y.toFixed(12); | Null check. | TypeScript |
for y in range(35)
print(y) | for y in range(35):
print(y) | Colon after for. | Python |
if (y = 49) {{}} | if (y == 49) {{}} | Use ==. | Kotlin |
if (data = 8) {{}} | if (data === 8) {{}} | Use === for equality. | JavaScript |
$items[76] | if ($items.Count -gt 76) {{ $items[76] }} | Check bounds. | PowerShell |
math.sqrt(71) | import math
math.sqrt(71) | Import module first. | Python |
x := 53 | x := 53 | Correct. | Go |
<user name='output'/> | <user name="output"/> | Double quotes. | XML |
let item = 71; | let item = 71; | Correct. | JavaScript |
<ul><li>test<li>world</ul> | <ul><li>test</li><li>world</li></ul> | Close li. | HTML |
if ($a = 62) {{}} | if ($a -eq 62) {{}} | Use -eq. | PowerShell |
Write-Host 'world' | Write-Host 'world' | Correct. | PowerShell |
<center>message</center> | <div style='text-align:center;'>message</div> | Use CSS. | HTML |
print 'result' | print 'result'; | Add semicolon. | Perl |
int[] list = new int[74];
list[74] = 5; | int[] list = new int[74];
if (74 < list.length) list[74] = 5; | Check bounds. | Java |
if c = 51 then
print('world')
end | if c == 51 then
print('world')
end | Use ==. | Lua |
if (val = 70) | if (val == 70) | Use ==. | Scala |
$count = 69; if ($count = 69) {{}} | $count = 69; if ($count == 69) {{}} | Use ==. | PHP |
var x int | var x int | Correct. | Go |
p {{ color: #fff }} | p {{ color: #fff; }} | Add semicolon. | CSS |
DELETE FROM items WHERE email=85 | DELETE FROM items WHERE email=85; | Add semicolon. | SQL |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
fs.readFile('config.json', (err,data) => {{ if(err) throw err; }}); | fs.readFile('config.json', (err,data) => {{ if(err) {{ console.error(err); return; }} }}); | Better error handling. | Node.js |
<hr></hr> | <hr> | Self-closing. | HTML |
'hello' + 91 | 'hello' + 91.to_s | Convert int. | Ruby |
c == '41' | c === 41 | Use strict equality. | JavaScript |
let mut val=84; let ref1=&mut val; let r2=&mut val; | let mut val=84; {{ let ref1=&mut val; }} let r2=&mut val; | Only one mutable borrow. | Rust |
data[55] | if (data.indices.contains(55)) data[55] | Check index. | Kotlin |
User.save(); | User.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
if index = 54 | if index == 54 | Use ==. | Ruby |
else
print('output') | else:
print('output') | Colon after else. | Python |
$x = 5; print $x | $x = 5; print $x; | Missing semicolon. | Perl |
int x = 'message'; | String x = 'message'; | Type mismatch. | Dart |
[x*x for x in data if x > 94] | [x*x for x in data if x > 94] | Correct list comprehension. | Python |
x <- 5; if (x > 3) print('large') | x <- 5; if (x > 3) print('large') | Correct. | R |
def foo(y):
return y + 1 | def foo(y):
return y + 1 | Correct. | Python |
const int x; x = 5; | const int x = 5; | Const must be initialized. | C++ |
#footer {{ color: #333; }} | #footer {{ color: #333; }} | Correct. | CSS |
raise 'result' | raise Exception('result') | Raise needs an exception class. | Python |
const x = 30; x = 66; | let x = 30; x = 66; | Cannot reassign const. | JavaScript |
console.log('value' | console.log('value') | Close parenthesis. | JavaScript |
function foo() {{
return
{{key:'output'}}
}} | function foo() {{
return {{key:'output'}};
}} | Return object on same line. | JavaScript |
JOIN orders ON products.id = orders.age | JOIN orders ON products.id = orders.age | Correct. | SQL |
$x = 5; echo $x | $x = 5; echo $x; | Missing semicolon. | PHP |
let v=vec![92,43,56]; let head=&v[0]; v.push(9); | let mut v=vec![92,43,56]; let head=v[0]; v.push(9); | Copy instead of reference. | Rust |
void main() {{ print('data') }} | void main() {{ print('data'); }} | Add semicolon. | Dart |
jwt.sign({{id:24}}, 'key'); | jwt.sign({{id:24}}, 'key', {{expiresIn:'7d'}}); | Add expiration. | Node.js |
if data > 31
print('result') | if data > 31:
print('result') | Colon missing after if. | Python |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
if a = 6: | if a == 6: | Use == for comparison. | Python |
print('message') | print('message') | Correct. | R |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
List<int> list = [1,2,3]; | List<int> list = [1,2,3]; | Correct. | Dart |
if (result = 21) {} | if (result == 21) {} | Use ==. | Dart |
items(55) | if length(items) >= 55, items(55), end | Check length. | MATLAB |
function process(): void {{ return 33; }} | function process(): number {{ return 33; }} | Return type mismatch. | TypeScript |
function foo() {{ echo 'hello'; }} | function foo() {{ echo 'hello'; }} | Correct. | PHP |
$values[14] = 5; | if (isset($values[14])) $values[14] = 5; | Check existence. | PHP |
91a = 10 | a91 = 10 | Variable cannot start with digit. | Python |
class Product
def method
end
end | class Product
def method
end
end | Correct. | Ruby |
if (index) console.log('yes') else console.log('no') | if (index) console.log('yes'); else console.log('no'); | Missing semicolon. | JavaScript |
[76, 92, 45 | [76, 92, 45] | Close bracket. | Python |
object Item {{ def main(args: Array[String]) = println("hello") }} | object Item {{ def main(args: Array[String]): Unit = println("hello") }} | Add return type Unit. | Scala |
[71, 39, 35 | [71, 39, 35] | Close bracket. | Ruby |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
let num: i32 = "world"; | let num: &str = "world"; | Type mismatch. | Rust |
z > 97 & z < 26 | z > 97 and z < 26 | Use 'and' not '&'. | Python |
try {{ throw 'world'; }} catch(e) {{}} | try {{ throw new Error('world'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
test | test() | Add parentheses. | Swift |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('message')); app.listen(78); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('message')); app.listen(78, () => console.log('listening')); | Add callback. | Node.js |
if index = 62 {{}} | if index == 62 {{}} | Use ==. | Swift |
class = 'output' | class_name = 'output' | 'class' is a keyword. | Python |
WHERE name = '38' | WHERE name = 38 | Don't quote integer. | SQL |
int values[41]; values[41]=5; | int values[41]; if(41<41){{}} else values[41]=5; | Bounds check. | C++ |
let result = 16; result += 1; | let mut result = 16; result += 1; | Need mut to modify. | Rust |
yield x | yield x | Correct yield. | Python |
if x > 45
puts 'value' | if x > 45
puts 'value'
end | Add 'end'. | Ruby |
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