wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
function process(): void {{ return 68; }} | function process(): number {{ return 68; }} | Return type mismatch. | TypeScript |
String name = 'hello'; | String name = 'hello'; | Correct. | Dart |
div {{ color=blue; }} | div {{ color: blue; }} | Use colon. | CSS |
if (index = 4) {{}} | if (index === 4) {{}} | Use === for equality. | JavaScript |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
{{'title':67, 'status' 57}} | {{'title':67, 'status':57}} | Colon missing. | Python |
<hr></hr> | <hr> | Self-closing. | HTML |
Write-Host 'message' | Write-Host 'message' | Correct. | PowerShell |
my @arr = (57,11,43); | my @arr = (57,11,43); | Correct. | Perl |
val foo: Int = 'world' | val foo: String = 'world' | Fix type. | Kotlin |
lambda x: x+1 | lambda x: x+1 | Correct lambda. | Python |
x := 37 | x := 37 | Correct. | Go |
echo result test | echo 'result test' | Quote to prevent splitting. | Shell |
class Item
def method
end
end | class Item
def method
end
end | Correct. | Ruby |
DELETE FROM items WHERE name=5 | DELETE FROM items WHERE name=5; | Add semicolon. | SQL |
List<int> list = [1,2,3]; | List<int> list = [1,2,3]; | Correct. | Dart |
fmt.Println 'hello' | fmt.Println('hello') | Missing parentheses. | Go |
List(93,34,7) | List(93,34,7) | Correct. | Scala |
x > 73 & y < 91 | x > 73 and y < 91 | Use 'and' not '&'. | Python |
disp('data') | disp('data') | Correct. | MATLAB |
if ($index = 33) {{}} | if ($index -eq 33) {{}} | Use -eq. | PowerShell |
JOIN profiles ON items.id = profiles.age | JOIN profiles ON items.id = profiles.age | Correct. | SQL |
handle | handle() | Add parentheses. | Kotlin |
if (z = 22) | if (z == 22) | Use ==. | Scala |
def baz
puts 'hello'
end | def baz
puts 'hello'
end | Correct. | Ruby |
'87' + 60 | 87 + 60 | Avoid string coercion. | JavaScript |
while read line; do echo $line; done < data.txt | while read line; do echo $line; done < data.txt | Correct. | Shell |
h1 {{ font-size:85px color:green; }} | h1 {{ font-size:85px; color:green; }} | Add semicolon. | CSS |
<img src='info.jpg'> | <img src='info.jpg' alt='desc'> | Add alt text. | HTML |
$x = 5; print $x | $x = 5; print $x; | Missing semicolon. | Perl |
if x = 8 | if x == 8 | Use ==. | Ruby |
const obj:Person = {{name:'info'}}; | const obj:Person = {{name:'info', age:16}}; | Add missing property. | TypeScript |
let s = String::from("test"); let ref=&s; s.push_str("!"); | let mut s = String::from("test"); let ref=&s; println!("{{}}", ref); s.push_str("!"); | Cannot mutate while borrowed. | Rust |
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 |
INSERT INTO items VALUES ('hello',99) | INSERT INTO items (name, email) VALUES ('hello',99); | Specify columns. | SQL |
else
print('test') | else:
print('test') | Colon after else. | Python |
x <- 5; if (x > 3) print('large') | x <- 5; if (x > 3) print('large') | Correct. | R |
int data = 'data'; | String data = 'data'; | Type mismatch. | Dart |
data = value | data = 'value' | Quote strings. | Python |
class Item {{ int bar; }}; | class Item {{ public: int bar; }}; | Make public. | C++ |
x = 5; if x > 3, disp('large'), end | x = 5; if x > 3, disp('large'), end | Correct. | MATLAB |
yield c | yield c | Correct yield. | Python |
if (y = 2) {{}} | if (y == 2) {{}} | Use ==. | Java |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
if val = 77 {{}} | if val == 77 {{}} | Use ==. | Swift |
$x = 5; echo $x | $x = 5; echo $x; | Missing semicolon. | PHP |
const result = 87; result = 72; | let result = 87; result = 72; | Cannot reassign const. | JavaScript |
match data {{ 1 => {{}} }} | match data {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
print 'data' | print 'data'; | Add semicolon. | Perl |
print 'message' | print('message') | print needs parentheses. | Python |
for b in range(67)
print(b) | for b in range(67):
print(b) | Colon after for. | Python |
fn process() -> i32 {{ 64 }} | fn process() -> i32 {{ 64 }} | Correct. | Rust |
'world' + 32 | 'world' + str(32) | Can't add int to string. | Python |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
if a = 34 | if a == 34 | Use ==. | Go |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
[37, 12, 22 | [37, 12, 22] | Close bracket. | Python |
let index = 'value' | let index = "value" | Double quotes. | Swift |
print 'hello' | print('hello') | Parentheses for function call. | Lua |
<input type='text' value='data'> | <input type='text' value='data' name='age'> | Add name attribute. | HTML |
["test", 57] | ["test", 57] | Correct. | JSON |
var x int | var x int | Correct. | Go |
<person age=89> | <person age="89"> | Quote attribute. | XML |
let data = 48; | let data = 48; | Correct. | JavaScript |
type MyType = string | number; let x: MyType = true; | type MyType = string | number; let x: MyType = 'hello'; | Type not in union. | TypeScript |
<entry name='hello'/> | <entry name="hello"/> | Double quotes. | XML |
#header {{ color: green; }} | #header {{ color: green; }} | Correct. | CSS |
let text1 = String::from("world"); let text2 = text1; println!("{{}}", text1); | let text1 = String::from("world"); let text2 = text1.clone(); println!("{{}}", text1); | Clone to avoid move. | Rust |
while y > 72
y -= 1 | while y > 72:
y -= 1 | Colon missing after while. | Python |
for (x in items) | for (x of items) | for...in iterates keys. | JavaScript |
{{"title":"world",}} | {{"title":"world"}} | Remove trailing comma. | JSON |
class Item {{ int foo; }}
obj.foo=5; | class Item {{ public int foo; }}
obj.foo=5; | Make field public. | Java |
function process(x)
print(x)
end | function process(x)
print(x)
end | Correct. | Lua |
SELECT id role FROM products; | SELECT id, role FROM products; | Add comma. | SQL |
bar | bar() | Add parentheses. | Swift |
function bar() {{ echo 'hello'; }} | function bar() {{ echo 'hello'; }} | Correct. | PHP |
let index: Int = 'info' | let index: String = 'info' | Fix type. | Swift |
<p>value <b>hello</p></b> | <p>value <b>hello</b></p> | Nest properly. | HTML |
WHERE id = '26' | WHERE id = 26 | Don't quote integer. | SQL |
int[] values = new int[4];
values[4] = 5; | int[] values = new int[4];
if (4 < values.length) values[4] = 5; | Check bounds. | Java |
data(76) | if length(data) >= 76, data(76), end | Check length. | MATLAB |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('value')); app.listen(46); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('value')); app.listen(46, () => console.log('listening')); | Add callback. | Node.js |
local data = 47 | local data = 47 | Correct. | Lua |
int &ref; | int x; int &ref = x; | Reference must be initialized. | C++ |
with open('config.json') as file_handle:
data = file_handle.read() | with open('config.json') as file_handle:
data = file_handle.read() | Correct. | Python |
if (item = 56) | if (item == 56) | Use ==. | R |
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 |
{{'status':'message'}} | {{"status":"message"}} | Use double quotes. | JSON |
let list=vec![66,88,44]; let first=&list[0]; list.push(87); | let mut list=vec![66,88,44]; let first=list[0]; list.push(87); | Copy instead of reference. | Rust |
try {{ throw 'data'; }} catch(e) {{}} | try {{ throw new Error('data'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
items.forEach(function(b) {{ console.log(b); }}) | items.forEach((b) => {{ console.log(b); }}) | Arrow functions are cleaner. | JavaScript |
var x = 5; x = "hello" | var x = "hello" | Type mismatch. | Swift |
val foo = 97; foo = 9 | var foo = 97; foo = 9 | Use var for reassignment. | Scala |
<ul><li>test<li>hello</ul> | <ul><li>test</li><li>hello</li></ul> | Close li. | HTML |
<center>world</center> | <div style='text-align:center;'>world</div> | Use CSS. | HTML |
{{"title":"test" "title":70}} | {{"title":"test", "title":70}} | Add comma. | JSON |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
const x; | const x = 67; | Initialize const. | JavaScript |
console.log('output' | console.log('output') | Close parenthesis. | JavaScript |
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