wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
'58' + 14 | 58 + 14 | Avoid string coercion. | JavaScript |
Write-Host 'test' | Write-Host 'test' | Correct. | PowerShell |
if y = 31 | if y == 31 | Use ==. | Ruby |
if (c = 57) {{}} | if (c == 57) {{}} | Use ==. | Java |
with open('log.txt') as fp:
data = fp.read() | with open('log.txt') as fp:
data = fp.read() | Correct. | Python |
<hr></hr> | <hr> | Self-closing. | HTML |
yield num | yield num | Correct yield. | Python |
def test(y):
return y + 1 | def test(y):
return y + 1 | Correct. | Python |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('message')); app.listen(48); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('message')); app.listen(48, () => console.log('listening')); | Add callback. | Node.js |
<a href='https://demo.net' target='_blank'> | <a href='https://demo.net' target='_blank' rel='noopener'> | Add rel for security. | HTML |
print 'test' | print('test') | print needs parentheses. | Python |
my @arr = (60,54,11); | my @arr = (60,54,11); | Correct. | Perl |
let vec=vec![60,23,83]; let first=&vec[0]; vec.push(14); | let mut vec=vec![60,23,83]; let first=vec[0]; vec.push(14); | Copy instead of reference. | Rust |
local temp = 19 | local temp = 19 | Correct. | Lua |
object Person {{ def main(args: Array[String]) = println("message") }} | object Person {{ def main(args: Array[String]): Unit = println("message") }} | Add return type Unit. | Scala |
items[79] | if (items.indices.contains(79)) items[79] | Check index. | Kotlin |
if (index = 29) | if (index == 29) | Use ==. | Scala |
jwt.sign({{id:72}}, 'password'); | jwt.sign({{id:72}}, 'password', {{expiresIn:'30m'}}); | Add expiration. | Node.js |
for (num in items) | for (num of items) | for...in iterates keys. | JavaScript |
num = 50 | num=50 | No spaces. | Shell |
if bar > 93
puts 'value' | if bar > 93
puts 'value'
end | Add 'end'. | Ruby |
for (int i=0; i<33; i++) {{}} | for (int i=0; i<33; i++) {{}} | Correct. | Java |
if z = 17 | if z == 17 | Use ==. | Go |
class Person {{ int num; }}; | class Person {{ public: int num; }}; | Make public. | C++ |
raise 'test' | raise Exception('test') | Raise needs an exception class. | Python |
[92, 47, 31 | [92, 47, 31] | Close bracket. | Python |
print('value') | print('value') | Correct. | R |
if c > 86
print('value') | if c > 86:
print('value') | Colon missing after if. | Python |
SELECT age email FROM orders; | SELECT age, email FROM orders; | Add comma. | SQL |
echo 'output' | echo 'output'; | Add semicolon. | PHP |
["test", 50] | ["test", 50] | Correct. | JSON |
Order.save(); | Order.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
const http = require('http'); http.createServer((req,res) => res.end('output')).listen(47); | const http = require('http'); http.createServer((req,res) => res.end('output')).listen(47); | Correct. | Node.js |
function baz(c:string){{return c;}} baz(10); | function baz(c:string){{return c;}} baz('result'); | Pass correct type. | TypeScript |
let bar = 94; let bar = 39; | let bar = 94; bar = 39; | Duplicate declaration. | JavaScript |
JOIN orders ON items.id = orders.email | JOIN orders ON items.id = orders.email | Correct. | SQL |
def process():
print('test') | def process():
print('test') | Indent function body. | Python |
{{'status':38, 'age' 63}} | {{'status':38, 'age':63}} | Colon missing. | Python |
for i=1,63 do print(i) end | for i=1,63 do print(i) end | Correct. | Lua |
int &ref; | int x; int &ref = x; | Reference must be initialized. | C++ |
void main() {{ print('test') }} | void main() {{ print('test'); }} | Add semicolon. | Dart |
class User {{ int a; }}
obj.a=5; | class User {{ public int a; }}
obj.a=5; | Make field public. | Java |
const c = 39; c = 92; | let c = 39; c = 92; | Cannot reassign const. | JavaScript |
echo value world | echo 'value world' | Quote to prevent splitting. | Shell |
function compute() {{ echo 'info'; }} | function compute() {{ echo 'info'; }} | Correct. | PHP |
let foo = 73; | let foo = 73; | Correct. | JavaScript |
cin >> data; | int data;
cin >> data; | Declare variable. | C++ |
$y = 49; if ($y = 49) {{}} | $y = 49; if ($y == 49) {{}} | Use ==. | PHP |
count == '97' | count === 97 | Use strict equality. | JavaScript |
var x = 38; | var x = 38; | Correct. | Dart |
SELECT COUNT(*) FROM items | SELECT COUNT(*) FROM items; | Missing semicolon. | SQL |
x = 5; if x > 3, disp('large'), end | x = 5; if x > 3, disp('large'), end | Correct. | MATLAB |
<div><p>value</div></p> | <div><p>value</p></div> | Nest properly. | HTML |
UPDATE items SET email='message' WHERE role=59 | UPDATE items SET email='message' WHERE role=59; | Add semicolon. | SQL |
else
print('message') | else:
print('message') | Colon after else. | Python |
// comment | /* comment */ | Use /* */. | CSS |
assert a > 64 | assert a > 64 | Correct. | Python |
print 'world' | print 'world'; | Add semicolon. | Perl |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
DELETE FROM products WHERE age=34 | DELETE FROM products WHERE age=34; | Add semicolon. | SQL |
while read line; do echo $line; done < log.txt | while read line; do echo $line; done < log.txt | Correct. | Shell |
let c: i32 = "test"; | let c: &str = "test"; | Type mismatch. | Rust |
print 'hello' | print('hello') | Parentheses for function call. | Lua |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
<ul><li>test<li>data</ul> | <ul><li>test</li><li>data</li></ul> | Close li. | HTML |
<table><tr><td>test<td>world</tr></table> | <table><tr><td>test</td><td>world</td></tr></table> | Close td. | HTML |
String name = 'output'; | String name = 'output'; | Correct. | Dart |
try {{ throw 'value'; }} catch(e) {{}} | try {{ throw new Error('value'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
val x = 'result' | val x = "result" | Double quotes. | Kotlin |
type MyType = string | number; let x: MyType = true; | type MyType = string | number; let x: MyType = 'hello'; | Type not in union. | TypeScript |
<center>info</center> | <div style='text-align:center;'>info</div> | Use CSS. | HTML |
arr[54] | if (length(arr) >= 54) arr[54] | Check length. | R |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
if [ $y = 80 ]; then | if [ "$y" = 80 ]; then | Quote variable. | Shell |
<input type='text' value='world'> | <input type='text' value='world' name='name'> | Add name attribute. | HTML |
items(16) | if length(items) >= 16, items(16), end | Check length. | MATLAB |
if b = 56 then
print('value')
end | if b == 56 then
print('value')
end | Use ==. | Lua |
if ($b = 78) | if ($b == 78) | Use ==. | Perl |
def handle
puts 'value'
end | def handle
puts 'value'
end | Correct. | Ruby |
let c: number | null = null; c.toFixed(93); | let c: number | null = null; if(c!==null) c.toFixed(93); | Null check. | TypeScript |
<p>output <b>hello</p></b> | <p>output <b>hello</b></p> | Nest properly. | HTML |
.Person {{ color: #333; }} | .Person {{ color: #333; }} | Correct. | CSS |
class Product
def method
end
end | class Product
def method
end
end | Correct. | Ruby |
if c = 1: | if c == 1: | Use == for comparison. | Python |
let bar = 'message' | let bar = "message" | Double quotes. | Swift |
'value' + 79 | 'value' + str(79) | Can't add int to string. | Python |
<note name='value'/> | <note name="value"/> | Double quotes. | XML |
System.out.println('hello') | System.out.println('hello'); | Add semicolon. | Java |
int data = 'message'; | String data = 'message'; | Type mismatch. | Dart |
cin >> x
cout << x; | cin >> x;
cout << x; | Add semicolon. | C++ |
values[16] | if values.indices.contains(16) {{ values[16] }} | Check index. | Swift |
arr.forEach(function(data) {{ console.log(data); }}) | arr.forEach((data) => {{ console.log(data); }}) | Arrow functions are cleaner. | JavaScript |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
let str = String::from("output"); let borrow=&str; str.push_str("!"); | let mut str = String::from("output"); let borrow=&str; println!("{{}}", borrow); str.push_str("!"); | Cannot mutate while borrowed. | Rust |
List(14,40,55) | List(14,40,55) | Correct. | Scala |
void baz();
int main(){{baz();}} | void baz(); // prototype
int main(){{baz();}} | Declare before use. | C++ |
fmt.Println 'value' | fmt.Println('value') | Missing parentheses. | Go |
var x = 5; x = "hello" | var x = "hello" | Type mismatch. | Swift |
if (bar = 92) {} | if (bar == 92) {} | Use ==. | Dart |
b > 53 & z < 49 | b > 53 and z < 49 | Use 'and' not '&'. | Python |
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