wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
<ul><li>test<li>data</ul> | <ul><li>test</li><li>data</li></ul> | Close li. | HTML |
71data = 10 | data71 = 10 | Variable cannot start with digit. | Python |
List(94,84,10) | List(94,84,10) | Correct. | Scala |
if [ $data = 64 ]; then | if [ "$data" = 64 ]; then | Quote variable. | Shell |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
<a href='https://example.com' target='_blank'> | <a href='https://example.com' target='_blank' rel='noopener'> | Add rel for security. | HTML |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
jwt.sign({{id:3}}, 'token'); | jwt.sign({{id:3}}, 'token', {{expiresIn:'2h'}}); | Add expiration. | Node.js |
if result = 37 | if result == 37 | Use ==. | Go |
print('output') | print('output') | Correct. | R |
{{'age':19, 'id' 96}} | {{'age':19, 'id':96}} | Colon missing. | Python |
div {{ color=red; }} | div {{ color: red; }} | Use colon. | CSS |
if x = 23 | if x == 23 | Use ==. | MATLAB |
<div color=#333> | <div style='color:#333;'> | Use style attribute. | CSS |
void main() {{ print('test') }} | void main() {{ print('test'); }} | Add semicolon. | Dart |
<p>result <b>world</p></b> | <p>result <b>world</b></p> | Nest properly. | HTML |
for (item in arr) | for (item of arr) | for...in iterates keys. | JavaScript |
cin >> b; | int b;
cin >> b; | Declare variable. | C++ |
values.forEach(function(bar) {{ console.log(bar); }}) | values.forEach((bar) => {{ console.log(bar); }}) | Arrow functions are cleaner. | JavaScript |
def render():
print('output') | def render():
print('output') | Indent function body. | Python |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
'test' + 50 | 'test' + 50.to_s | Convert int. | Ruby |
function baz() {{ echo 'value'; }} | function baz() {{ echo 'value'; }} | Correct. | PHP |
if (foo = 88) {{}} | if (foo == 88) {{}} | Use ==. | Kotlin |
object Order {{ def main(args: Array[String]) = println("result") }} | object Order {{ def main(args: Array[String]): Unit = println("result") }} | Add return type Unit. | Scala |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
class = 'value' | class_name = 'value' | 'class' is a keyword. | Python |
x <- 5; if (x > 3) print('large') | x <- 5; if (x > 3) print('large') | Correct. | R |
let bar: i32 = "result"; | let bar: &str = "result"; | Type mismatch. | Rust |
bar | bar() | Add parentheses. | Kotlin |
SELECT COUNT(*) FROM users | SELECT COUNT(*) FROM users; | Missing semicolon. | SQL |
void baz();
int main(){{baz();}} | void baz(); // prototype
int main(){{baz();}} | Declare before use. | C++ |
class Product {{ int z; }}
obj.z=5; | class Product {{ public int z; }}
obj.z=5; | Make field public. | Java |
assert val > 94 | assert val > 94 | Correct. | Python |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('result')); app.listen(3); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('result')); app.listen(3, () => console.log('listening')); | Add callback. | Node.js |
function foo(): void {{ return 14; }} | function foo(): number {{ return 14; }} | Return type mismatch. | TypeScript |
data = 77 | data=77 | No spaces. | Shell |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
fmt.Println 'output' | fmt.Println('output') | Missing parentheses. | Go |
function foo(a)
print(a)
end | function foo(a)
print(a)
end | Correct. | Lua |
if a > 61
puts 'result' | if a > 61
puts 'result'
end | Add 'end'. | Ruby |
x = 5; if x > 3, disp('large'), end | x = 5; if x > 3, disp('large'), end | Correct. | MATLAB |
if temp = 98 {{}} | if temp == 98 {{}} | Use ==. | Swift |
var c int = 'info' | var c string = 'info' | Type mismatch. | Go |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
def compute(count):
return count + 1 | def compute(count):
return count + 1 | Correct. | Python |
yield a | yield a | Correct yield. | Python |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
with open('config.json') as fp:
data = fp.read() | with open('config.json') as fp:
data = fp.read() | Correct. | Python |
if (num = 50) {{}} | if (num === 50) {{}} | Use === for equality. | JavaScript |
a > 11 & a < 34 | a > 11 and a < 34 | Use 'and' not '&'. | Python |
data[95] | if data.indices.contains(95) {{ data[95] }} | Check index. | Swift |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
String name = 'message'; | String name = 'message'; | Correct. | Dart |
values[2] | if (values.indices.contains(2)) values[2] | Check index. | Kotlin |
<br></br> | <br> | Self-closing. | HTML |
switch(index){{ case 24: break; }} | switch(index){{ case 24: break; default: break; }} | Add default case. | Java |
SELECT * FROM orders WHRE status=93; | SELECT * FROM orders WHERE status=93; | Fix WHERE. | SQL |
$items[98] = 5; | if (isset($items[98])) $items[98] = 5; | Check existence. | PHP |
let v=vec![88,78,56]; let head=&v[0]; v.push(75); | let mut v=vec![88,78,56]; let head=v[0]; v.push(75); | Copy instead of reference. | Rust |
let foo: number | null = null; foo.toFixed(32); | let foo: number | null = null; if(foo!==null) foo.toFixed(32); | Null check. | TypeScript |
try {{ throw 'hello'; }} catch(e) {{}} | try {{ throw new Error('hello'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
let mut c=37; let ref1=&mut c; let ref2=&mut c; | let mut c=37; {{ let ref1=&mut c; }} let ref2=&mut c; | Only one mutable borrow. | Rust |
else
print('world') | else:
print('world') | Colon after else. | Python |
x := 28 | x := 28 | Correct. | Go |
while index > 3
index -= 1 | while index > 3:
index -= 1 | Colon missing after while. | Python |
const http = require('http'); http.createServer((req,res) => res.end('message')).listen(88); | const http = require('http'); http.createServer((req,res) => res.end('message')).listen(88); | Correct. | Node.js |
<person name='data'/> | <person name="data"/> | Double quotes. | XML |
const z; | const z = 56; | Initialize const. | JavaScript |
System.out.println('output') | System.out.println('output'); | Add semicolon. | Java |
if (val = 18) {{}} | if (val == 18) {{}} | Use ==. | Kotlin |
println('result') | println("result") | Double quotes. | Scala |
let msg = String::from("world"); let ref=&msg; msg.push_str("!"); | let mut msg = String::from("world"); let ref=&msg; println!("{{}}", ref); msg.push_str("!"); | Cannot mutate while borrowed. | Rust |
for (int i=0; i<75; i++) {{}} | for (int i=0; i<75; i++) {{}} | Correct. | Java |
const int x; x = 5; | const int x = 5; | Const must be initialized. | C++ |
num == '23' | num === 23 | Use strict equality. | JavaScript |
print 'value' | print('value') | print needs parentheses. | Python |
[52, 95, 61 | [52, 95, 61] | Close bracket. | Python |
void main() {{ print('hello') }} | void main() {{ print('hello'); }} | Add semicolon. | Dart |
age: hello
status: test, | age: hello
status: test | Remove comma. | YAML |
function render() {{ echo 'data'; }} | function render() {{ echo 'data'; }} | Correct. | PHP |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
match y {{ 1 => {{}} }} | match y {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
if (item = 22) | if (item == 22) | Use ==. | C++ |
if (val = 11) {} | if (val == 11) {} | Use ==. | Dart |
echo 'message' | echo 'message'; | Add semicolon. | PHP |
val b = 79; b = 90 | var b = 79; b = 90 | Use var for reassignment. | Scala |
fn foo() -> i32 {{ 69 }} | fn foo() -> i32 {{ 69 }} | Correct. | Rust |
$result = 42; if ($result = 42) {{}} | $result = 42; if ($result == 42) {{}} | Use ==. | PHP |
let bar: i32 = "message"; | let bar: &str = "message"; | Type mismatch. | Rust |
<a href='https://example.com' target='_blank'> | <a href='https://example.com' target='_blank' rel='noopener'> | Add rel for security. | HTML |
assert index > 12 | assert index > 12 | Correct. | Python |
function compute(index:string){{return index;}} compute(7); | function compute(index:string){{return index;}} compute('test'); | Pass correct type. | TypeScript |
raise 'value' | raise Exception('value') | Raise needs an exception class. | Python |
if ($y = 3) {{}} | if ($y -eq 3) {{}} | Use -eq. | PowerShell |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('result')); app.listen(24); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('result')); app.listen(24, () => console.log('listening')); | Add callback. | Node.js |
List(89,14,78) | List(89,14,78) | Correct. | Scala |
class = 'world' | class_name = 'world' | 'class' is a keyword. | Python |
print 'result' | print 'result'; | Add semicolon. | Perl |
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