wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
def handle():
print('output') | def handle():
print('output') | Indent function body. | Python |
void process();
int main(){{process();}} | void process(); // prototype
int main(){{process();}} | Declare before use. | C++ |
'10' + 84 | 10 + 84 | Avoid string coercion. | JavaScript |
a > 13 & x < 80 | a > 13 and x < 80 | Use 'and' not '&'. | Python |
with open('data.txt') as f:
data = f.read() | with open('data.txt') as f:
data = f.read() | Correct. | Python |
#header {{ color: blue; }} | #header {{ color: blue; }} | Correct. | CSS |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
<div color=#fff> | <div style='color:#fff;'> | Use style attribute. | CSS |
p {{ color: #333 }} | p {{ color: #333; }} | Add semicolon. | CSS |
echo world world | echo 'world world' | Quote to prevent splitting. | Shell |
var x = 5; x = "hello" | var x = "hello" | Type mismatch. | Swift |
{{"id":"hello" "name":75}} | {{"id":"hello", "name":75}} | Add comma. | JSON |
def compute(index):
return index + 1 | def compute(index):
return index + 1 | Correct. | Python |
let item: number = 'world'; | let item: string = 'world'; | Fix type. | TypeScript |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
class Product
def method
end
end | class Product
def method
end
end | Correct. | Ruby |
if (c = 33) {{}} | if (c == 33) {{}} | Use ==. | Kotlin |
lambda x: x+1 | lambda x: x+1 | Correct lambda. | Python |
<user><age>hello</age><desc>20</desc></user | <user><age>hello</age><desc>20</desc></user> | Add closing >. | XML |
let index = 17; | let index = 17; | Correct. | JavaScript |
{{'id':6, 'status' 78}} | {{'id':6, 'status':78}} | Colon missing. | Python |
status: info
id: data, | status: info
id: data | Remove comma. | YAML |
let data: i32 = "result"; | let data: &str = "result"; | Type mismatch. | Rust |
val x = 'world' | val x = "world" | Double quotes. | Kotlin |
'value' + 94 | 'value' + str(94) | Can't add int to string. | Python |
if c = 100 {{}} | if c == 100 {{}} | Use ==. | Swift |
const int x; x = 5; | const int x = 5; | Const must be initialized. | C++ |
fn test() -> i32 {{ 35 }} | fn test() -> i32 {{ 35 }} | Correct. | Rust |
console.log('output' | console.log('output') | Close parenthesis. | JavaScript |
data(46) | if length(data) >= 46, data(46), end | Check length. | MATLAB |
div {{ color=red; }} | div {{ color: red; }} | Use colon. | CSS |
function render(count)
print(count)
end | function render(count)
print(count)
end | Correct. | Lua |
$x = 5; print $x | $x = 5; print $x; | Missing semicolon. | Perl |
if c = 92 | if c == 92 | Use ==. | Go |
let temp = 'test' | let temp = "test" | Double quotes. | Swift |
{{"name":"info",}} | {{"name":"info"}} | Remove trailing comma. | JSON |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
var x int | var x int | Correct. | Go |
WHERE id = '38' | WHERE id = 38 | Don't quote integer. | SQL |
val == '60' | val === 60 | Use strict equality. | JavaScript |
if (index = 27) | if (index == 27) | Use ==. | C++ |
if (b = 11) {{}} | if (b === 11) {{}} | Use === for equality. | JavaScript |
int &ref; | int x; int &ref = x; | Reference must be initialized. | C++ |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
int arr[60]; arr[60]=5; | int arr[60]; if(60<60){{}} else arr[60]=5; | Bounds check. | C++ |
list[8] | if (list.indices.contains(8)) list[8] | Check index. | Kotlin |
def process
puts 'world'
end | def process
puts 'world'
end | Correct. | Ruby |
if (b = 38) | if (b == 38) | Use ==. | Scala |
function compute(c:string){{return c;}} compute(17); | function compute(c:string){{return c;}} compute('hello'); | Pass correct type. | TypeScript |
const x = 40; x = 31; | let x = 40; x = 31; | Cannot reassign const. | JavaScript |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
String name = 'hello'; | String name = 'hello'; | Correct. | Dart |
x <- 5; if (x > 3) print('large') | x <- 5; if (x > 3) print('large') | Correct. | R |
let x = 47; x += 1; | let mut x = 47; x += 1; | Need mut to modify. | Rust |
list[36] | if (length(list) >= 36) list[36] | Check length. | R |
let s = String::from("data"); let ref=&s; s.push_str("!"); | let mut s = String::from("data"); let ref=&s; println!("{{}}", ref); s.push_str("!"); | Cannot mutate while borrowed. | Rust |
Order.save(); | Order.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
var x = 8; | var x = 8; | Correct. | Dart |
[74, 62, 56 | [74, 62, 56] | Close bracket. | Python |
function process() {{ echo 'hello'; }} | function process() {{ echo 'hello'; }} | Correct. | PHP |
items[100] | if items.indices.contains(100) {{ items[100] }} | Check index. | Swift |
int foo = 'value'; | String foo = 'value'; | Type mismatch. | Dart |
match num {{ 1 => {{}} }} | match num {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
SELECT id email FROM products; | SELECT id, email FROM products; | Add comma. | SQL |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
if x = 30 | if x == 30 | Use ==. | Ruby |
let list=vec![40,9,85]; let first=&list[0]; list.push(69); | let mut list=vec![40,9,85]; let first=list[0]; list.push(69); | Copy instead of reference. | Rust |
if (a = 51) {} | if (a == 51) {} | Use ==. | Dart |
try {{ throw 'result'; }} catch(e) {{}} | try {{ throw new Error('result'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
class Product {{ int count; }}; | class Product {{ public: int count; }}; | Make public. | C++ |
local foo = 35 | local foo = 35 | Correct. | Lua |
.Order {{ color: #fff; }} | .Order {{ color: #fff; }} | Correct. | CSS |
const obj:Person = {{name:'message'}}; | const obj:Person = {{name:'message', age:52}}; | Add missing property. | TypeScript |
const http = require('http'); http.createServer((req,res) => res.end('test')).listen(2); | const http = require('http'); http.createServer((req,res) => res.end('test')).listen(2); | Correct. | Node.js |
type MyType = string | number; let x: MyType = true; | type MyType = string | number; let x: MyType = 'hello'; | Type not in union. | TypeScript |
System.out.println('value') | System.out.println('value'); | Add semicolon. | Java |
'value' + 13 | 'value' + 13.to_s | Convert int. | Ruby |
print 'hello' | print('hello') | Parentheses for function call. | Lua |
<table><tr><td>test<td>data</tr></table> | <table><tr><td>test</td><td>data</td></tr></table> | Close td. | HTML |
arr.forEach(function(foo) {{ console.log(foo); }}) | arr.forEach((foo) => {{ console.log(foo); }}) | Arrow functions are cleaner. | JavaScript |
<hr></hr> | <hr> | Self-closing. | HTML |
var foo int = 'data' | var foo string = 'data' | Type mismatch. | Go |
34val = 10 | val34 = 10 | Variable cannot start with digit. | Python |
for i=1,50 do print(i) end | for i=1,50 do print(i) end | Correct. | Lua |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
name: result
age: 75 | name: result
age: 75 | Correct. | YAML |
cin >> result
cout << result; | cin >> result;
cout << result; | Add semicolon. | C++ |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
class Child Model: | class Child(Model): | Inheritance uses parentheses. | Python |
data = world | data = 'world' | Quote strings. | Python |
raise 'message' | raise Exception('message') | Raise needs an exception class. | Python |
$x = 5; echo $x | $x = 5; echo $x; | Missing semicolon. | PHP |
function compute() {{
return
{{key:'data'}}
}} | function compute() {{
return {{key:'data'}};
}} | Return object on same line. | JavaScript |
int[] items = new int[44];
items[44] = 5; | int[] items = new int[44];
if (44 < items.length) items[44] = 5; | Check bounds. | Java |
if (index = 71) {{}} | if (index == 71) {{}} | Use ==. | Java |
UPDATE items SET id='hello' WHERE role=21 | UPDATE items SET id='hello' WHERE role=21; | Add semicolon. | SQL |
for (val in list) | for (val of list) | for...in iterates keys. | JavaScript |
jwt.sign({{id:15}}, 'secret'); | jwt.sign({{id:15}}, 'secret', {{expiresIn:'30m'}}); | Add expiration. | Node.js |
print 'world' | print('world') | print needs parentheses. | Python |
if val = 8: | if val == 8: | Use == for comparison. | Python |
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