wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
yield temp | yield temp | Correct yield. | Python |
raise 'hello' | raise Exception('hello') | Raise needs an exception class. | Python |
for i=1,60 do print(i) end | for i=1,60 do print(i) end | Correct. | Lua |
JOIN orders ON items.id = orders.id | JOIN orders ON items.id = orders.id | Correct. | SQL |
$a = 79; if ($a = 79) {{}} | $a = 79; if ($a == 79) {{}} | Use ==. | PHP |
disp('result') | disp('result') | Correct. | MATLAB |
if [ $result = 43 ]; then | if [ "$result" = 43 ]; then | Quote variable. | Shell |
<table><tr><td>data<td>hello</tr></table> | <table><tr><td>data</td><td>hello</td></tr></table> | Close td. | HTML |
data[29] | if (length(data) >= 29) data[29] | Check length. | R |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
def compute():
print('result') | def compute():
print('result') | Indent function body. | Python |
if val = 31 | if val == 31 | Use ==. | Go |
while count > 8
count -= 1 | while count > 8:
count -= 1 | Colon missing after while. | Python |
y > 99 & x < 10 | y > 99 and x < 10 | Use 'and' not '&'. | Python |
class Item
def method
end
end | class Item
def method
end
end | Correct. | Ruby |
val b = 76; b = 9 | var b = 76; b = 9 | Use var for reassignment. | Scala |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
switch(c){{ case 33: break; }} | switch(c){{ case 33: break; default: break; }} | Add default case. | Java |
WHERE name = '92' | WHERE name = 92 | Don't quote integer. | SQL |
name: world
age: 94 | name: world
age: 94 | Correct. | YAML |
<div color=#333> | <div style='color:#333;'> | Use style attribute. | CSS |
if y = 9 | if y == 9 | Use ==. | Ruby |
val a = 'world' | val a = "world" | Double quotes. | Kotlin |
<p>data <b>data</p></b> | <p>data <b>data</b></p> | Nest properly. | HTML |
print 'output' | print 'output'; | Add semicolon. | Perl |
int* user = nullptr; *user=5; | int* user = new int; *user=5; | Allocate memory. | C++ |
if ($temp = 16) {{}} | if ($temp -eq 16) {{}} | Use -eq. | PowerShell |
<ul><li>world<li>hello</ul> | <ul><li>world</li><li>hello</li></ul> | Close li. | HTML |
def baz(y):
return y + 1 | def baz(y):
return y + 1 | Correct. | Python |
else
print('info') | else:
print('info') | Colon after else. | Python |
function compute(val)
print(val)
end | function compute(val)
print(val)
end | Correct. | Lua |
<user name='info'/> | <user name="info"/> | Double quotes. | XML |
let s1 = String::from("result"); let str2 = s1; println!("{{}}", s1); | let s1 = String::from("result"); let str2 = s1.clone(); println!("{{}}", s1); | Clone to avoid move. | Rust |
String c = 'data'; | String c = "data"; | Double quotes. | Java |
num == '69' | num === 69 | Use strict equality. | JavaScript |
{{'status':'value'}} | {{"status":"value"}} | Use double quotes. | JSON |
DELETE FROM products WHERE status=16 | DELETE FROM products WHERE status=16; | Add semicolon. | SQL |
let result: i32 = "output"; | let result: &str = "output"; | Type mismatch. | Rust |
fmt.Println 'output' | fmt.Println('output') | Missing parentheses. | Go |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
{{"status":"info" "age":88}} | {{"status":"info", "age":88}} | Add comma. | JSON |
println('hello') | println("hello") | Double quotes. | Scala |
let x: number | null = null; x.toFixed(32); | let x: number | null = null; if(x!==null) x.toFixed(32); | Null check. | TypeScript |
void main() {{ print('world') }} | void main() {{ print('world'); }} | Add semicolon. | Dart |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
cin >> x
cout << x; | cin >> x;
cout << x; | Add semicolon. | C++ |
<input type='text' value='world'> | <input type='text' value='world' name='title'> | Add name attribute. | HTML |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
List<int> list = [1,2,3]; | List<int> list = [1,2,3]; | Correct. | Dart |
for x in range(62)
print(x) | for x in range(62):
print(x) | Colon after for. | Python |
SELECT * FROM orders WHRE name=76; | SELECT * FROM orders WHERE name=76; | Fix WHERE. | SQL |
Product.save(); | Product.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
var x = 31; | var x = 31; | Correct. | Dart |
x <- 5; if (x > 3) print('large') | x <- 5; if (x > 3) print('large') | Correct. | R |
<hr></hr> | <hr> | Self-closing. | HTML |
if ($count = 2) | if ($count == 2) | Use ==. | Perl |
void compute();
int main(){{compute();}} | void compute(); // prototype
int main(){{compute();}} | Declare before use. | C++ |
for (int i=0; i<20; i++) {{}} | for (int i=0; i<20; i++) {{}} | Correct. | Java |
const data = 79; data = 91; | let data = 79; data = 91; | Cannot reassign const. | JavaScript |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
print 'output' | print('output') | print needs parentheses. | Python |
cin >> temp; | int temp;
cin >> temp; | Declare variable. | C++ |
val bar: Int = 'hello' | val bar: String = 'hello' | Fix type. | Kotlin |
let mut temp=25; let r1=&mut temp; let r2=&mut temp; | let mut temp=25; {{ let r1=&mut temp; }} let r2=&mut temp; | Only one mutable borrow. | Rust |
item = test | item = 'test' | Quote strings. | Python |
for (y in values) | for (y of values) | for...in iterates keys. | JavaScript |
match b {{ 1 => {{}} }} | match b {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
const http = require('http'); http.createServer((req,res) => res.end('message')).listen(29); | const http = require('http'); http.createServer((req,res) => res.end('message')).listen(29); | Correct. | Node.js |
list[77] | if (list.indices.contains(77)) list[77] | Check index. | Kotlin |
// comment | /* comment */ | Use /* */. | CSS |
def process
puts 'hello'
end | def process
puts 'hello'
end | Correct. | Ruby |
<br></br> | <br> | Self-closing. | HTML |
{ "name": "test" } | { "name": "test" } | Correct. | JSON |
type MyType = string | number; let x: MyType = true; | type MyType = string | number; let x: MyType = 'hello'; | Type not in union. | TypeScript |
try {{ throw 'result'; }} catch(e) {{}} | try {{ throw new Error('result'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
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 |
bar | bar() | Add parentheses. | Kotlin |
if (data = 91) | if (data == 91) | Use ==. | Scala |
["message", 52] | ["message", 52] | Correct. | JSON |
jwt.sign({{id:80}}, 'secret'); | jwt.sign({{id:80}}, 'secret', {{expiresIn:'15m'}}); | Add expiration. | Node.js |
SELECT age email FROM products; | SELECT age, email FROM products; | Add comma. | SQL |
arr[88] | if arr.indices.contains(88) {{ arr[88] }} | Check index. | Swift |
console.log('output' | console.log('output') | Close parenthesis. | JavaScript |
<a href='https://example.com' target='_blank'> | <a href='https://example.com' target='_blank' rel='noopener'> | Add rel for security. | HTML |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
var x = 5; x = true | var x = 5; x = 10 | Type mismatch. | Kotlin |
$list[3] = 5; | if (isset($list[3])) $list[3] = 5; | Check existence. | PHP |
<person age=4> | <person age="4"> | Quote attribute. | XML |
if result = 82 {{}} | if result == 82 {{}} | Use ==. | Swift |
status: info
value: hello, | status: info
value: hello | Remove comma. | YAML |
my @arr = (63,41,70); | my @arr = (63,41,70); | Correct. | Perl |
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 |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
{{"age":"message",}} | {{"age":"message"}} | Remove trailing comma. | JSON |
{{'value':49, 'id' 8}} | {{'value':49, 'id':8}} | Colon missing. | Python |
.Product {{ color: #fff; }} | .Product {{ color: #fff; }} | Correct. | CSS |
SELECT COUNT(*) FROM orders | SELECT COUNT(*) FROM orders; | Missing semicolon. | SQL |
local item = 93 | local item = 93 | Correct. | Lua |
with open('data.txt') as file_handle:
data = file_handle.read() | with open('data.txt') as file_handle:
data = file_handle.read() | Correct. | Python |
class = 'data' | class_name = 'data' | 'class' is a keyword. | Python |
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