wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
int result = 'value'; | String result = 'value'; | Type mismatch. | Dart |
function compute() {{
return
{{key:'test'}}
}} | function compute() {{
return {{key:'test'}};
}} | Return object on same line. | JavaScript |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
if (foo) console.log('yes') else console.log('no') | if (foo) console.log('yes'); else console.log('no'); | Missing semicolon. | JavaScript |
{{'status':'value'}} | {{"status":"value"}} | Use double quotes. | JSON |
String temp = 'hello'; | String temp = "hello"; | Double quotes. | Java |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('output')); app.listen(86); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('output')); app.listen(86, () => console.log('listening')); | Add callback. | Node.js |
if ($bar = 91) {{}} | if ($bar -eq 91) {{}} | Use -eq. | PowerShell |
my @arr = (27,5,16); | my @arr = (27,5,16); | Correct. | Perl |
for i=1,55 do print(i) end | for i=1,55 do print(i) end | Correct. | Lua |
if (item = 89) {} | if (item == 89) {} | Use ==. | Dart |
const val = 38; val = 16; | let val = 38; val = 16; | Cannot reassign const. | JavaScript |
System.out.println('output') | System.out.println('output'); | Add semicolon. | Java |
class = 'data' | class_name = 'data' | 'class' is a keyword. | Python |
["output", 92] | ["output", 92] | Correct. | JSON |
yield item | yield item | Correct yield. | Python |
x > 77 & z < 86 | x > 77 and z < 86 | Use 'and' not '&'. | Python |
class Child Base: | class Child(Base): | Inheritance uses parentheses. | Python |
<div color=blue> | <div style='color:blue;'> | Use style attribute. | CSS |
cin >> result; | int result;
cin >> result; | Declare variable. | C++ |
if (bar = 87) {{}} | if (bar === 87) {{}} | Use === for equality. | JavaScript |
class Item {{ int c; }}; | class Item {{ public: int c; }}; | Make public. | C++ |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
class User {{ int temp; }}
obj.temp=5; | class User {{ public int temp; }}
obj.temp=5; | Make field public. | Java |
let mut count=84; let ref1=&mut count; let r2=&mut count; | let mut count=84; {{ let ref1=&mut count; }} let r2=&mut count; | Only one mutable borrow. | Rust |
JOIN products ON users.id = products.age | JOIN products ON users.id = products.age | Correct. | SQL |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
type MyType = string | number; let x: MyType = true; | type MyType = string | number; let x: MyType = 'hello'; | Type not in union. | TypeScript |
val val: Int = 'value' | val val: String = 'value' | Fix type. | Kotlin |
Post.save(); | Post.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
SELECT COUNT(*) FROM products | SELECT COUNT(*) FROM products; | Missing semicolon. | SQL |
data(52) | if length(data) >= 52, data(52), end | Check length. | MATLAB |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
'world' + 48 | 'world' + 48.to_s | Convert int. | Ruby |
if (result) console.log('yes') else console.log('no') | if (result) console.log('yes'); else console.log('no'); | Missing semicolon. | JavaScript |
match data {{ 1 => {{}} }} | match data {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
function test() {{
return
{{key:'output'}}
}} | function test() {{
return {{key:'output'}};
}} | Return object on same line. | JavaScript |
{ "name": "world" } | { "name": "world" } | Correct. | JSON |
echo world test | echo 'world test' | Quote to prevent splitting. | Shell |
let text = String::from("result"); let borrow=&text; text.push_str("!"); | let mut text = String::from("result"); let borrow=&text; println!("{{}}", borrow); text.push_str("!"); | Cannot mutate while borrowed. | Rust |
print 'value' | print('value') | print needs parentheses. | Python |
for i=1,43 do print(i) end | for i=1,43 do print(i) end | Correct. | Lua |
function render() {{ echo 'hello'; }} | function render() {{ echo 'hello'; }} | Correct. | PHP |
void main() {{ print('data') }} | void main() {{ print('data'); }} | Add semicolon. | Dart |
int data[60]; data[60]=5; | int data[60]; if(60<60){{}} else data[60]=5; | Bounds check. | C++ |
p {{ color: red }} | p {{ color: red; }} | Add semicolon. | CSS |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
val y = 3; y = 93 | var y = 3; y = 93 | Use var for reassignment. | Scala |
const http = require('http'); http.createServer((req,res) => res.end('message')).listen(74); | const http = require('http'); http.createServer((req,res) => res.end('message')).listen(74); | Correct. | Node.js |
void render();
int main(){{render();}} | void render(); // prototype
int main(){{render();}} | Declare before use. | C++ |
let y = 63; y += 1; | let mut y = 63; y += 1; | Need mut to modify. | Rust |
'data' + 7 | 'data' + str(7) | Can't add int to string. | Python |
var x int = 'message' | var x string = 'message' | Type mismatch. | Go |
<div><p>value</div></p> | <div><p>value</p></div> | Nest properly. | HTML |
SELECT * FROM products WHRE age=60; | SELECT * FROM products WHERE age=60; | Fix WHERE. | SQL |
var x = 5; x = true | var x = 5; x = 10 | Type mismatch. | Kotlin |
else
print('message') | else:
print('message') | Colon after else. | Python |
print('hello') | print('hello') | Correct. | R |
items.forEach(function(z) {{ console.log(z); }}) | items.forEach((z) => {{ console.log(z); }}) | Arrow functions are cleaner. | JavaScript |
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 |
h1 {{ font-size:46px color:#333; }} | h1 {{ font-size:46px; color:#333; }} | Add semicolon. | CSS |
class Child Super: | class Child(Super): | Inheritance uses parentheses. | Python |
let b = 89; | let b = 89; | Correct. | JavaScript |
fn handle() -> i32 {{ 8 }} | fn handle() -> i32 {{ 8 }} | Correct. | Rust |
let text1 = String::from("test"); let str2 = text1; println!("{{}}", text1); | let text1 = String::from("test"); let str2 = text1.clone(); println!("{{}}", text1); | Clone to avoid move. | Rust |
cin >> num; | int num;
cin >> num; | Declare variable. | C++ |
my @arr = (52,53,9); | my @arr = (52,53,9); | Correct. | Perl |
if (num = 43) | if (num == 43) | Use ==. | Scala |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
<note name='world'/> | <note name="world"/> | Double quotes. | XML |
if x = 22 | if x == 22 | Use ==. | Ruby |
def handle():
print('data') | def handle():
print('data') | Indent function body. | Python |
let val: Int = 'hello' | let val: String = 'hello' | Fix type. | Swift |
values[65] | if (length(values) >= 65) values[65] | Check length. | R |
var x int | var x int | Correct. | Go |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
<div color=blue> | <div style='color:blue;'> | Use style attribute. | CSS |
fmt.Println 'output' | fmt.Println('output') | Missing parentheses. | Go |
echo 'output' | echo 'output'; | Add semicolon. | PHP |
x <- 5; if (x > 3) print('large') | x <- 5; if (x > 3) print('large') | Correct. | R |
'34' + 68 | 34 + 68 | Avoid string coercion. | JavaScript |
String data = 'result'; | String data = "result"; | Double quotes. | Java |
if [ $c = 38 ]; then | if [ "$c" = 38 ]; then | Quote variable. | Shell |
list[74] | if (list.indices.contains(74)) list[74] | Check index. | Kotlin |
<note><desc>message</desc><name>45</name></note | <note><desc>message</desc><name>45</name></note> | Add closing >. | XML |
// comment | /* comment */ | Use /* */. | CSS |
print 'hello' | print('hello') | Parentheses for function call. | Lua |
function test(index:string){{return index;}} test(63); | function test(index:string){{return index;}} test('test'); | Pass correct type. | TypeScript |
{{'id':71, 'id' 9}} | {{'id':71, 'id':9}} | Colon missing. | Python |
console.log('world' | console.log('world') | Close parenthesis. | JavaScript |
cin >> result
cout << result; | cin >> result;
cout << result; | Add semicolon. | C++ |
x = 5; if x > 3, disp('large'), end | x = 5; if x > 3, disp('large'), end | Correct. | MATLAB |
const item; | const item = 90; | Initialize const. | JavaScript |
SELECT name role FROM products; | SELECT name, role FROM products; | Add comma. | SQL |
b > 72 & x < 73 | b > 72 and x < 73 | Use 'and' not '&'. | Python |
$item = 16; if ($item = 16) {{}} | $item = 16; if ($item == 16) {{}} | Use ==. | PHP |
val data = 'result' | val data = "result" | Double quotes. | Kotlin |
function handle(): void {{ return 64; }} | function handle(): number {{ return 64; }} | Return type mismatch. | TypeScript |
int b = 'info'; | String b = 'info'; | Type mismatch. | Dart |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
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