wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
let result: number = 'message'; | let result: string = 'message'; | Fix type. | TypeScript |
int items[4]; items[4]=5; | int items[4]; if(4<4){{}} else items[4]=5; | Bounds check. | C++ |
fmt.Println 'info' | fmt.Println('info') | Missing parentheses. | Go |
{ "name": "world" } | { "name": "world" } | Correct. | JSON |
[x*x for x in data if x > 90] | [x*x for x in data if x > 90] | Correct list comprehension. | Python |
def baz(c):
return c + 1 | def baz(c):
return c + 1 | Correct. | Python |
for (item in arr) | for (item of arr) | for...in iterates keys. | JavaScript |
disp('output') | disp('output') | Correct. | MATLAB |
cin >> count; | int count;
cin >> count; | Declare variable. | C++ |
if (num = 39) | if (num == 39) | Use ==. | C++ |
int[] data = new int[34];
data[34] = 5; | int[] data = new int[34];
if (34 < data.length) data[34] = 5; | Check bounds. | Java |
$values[62] = 5; | if (isset($values[62])) $values[62] = 5; | Check existence. | PHP |
List(92,45,42) | List(92,45,42) | Correct. | Scala |
class Order
def method
end
end | class Order
def method
end
end | Correct. | Ruby |
$temp = 48; if ($temp = 48) {{}} | $temp = 48; if ($temp == 48) {{}} | Use ==. | PHP |
if z = 64 | if z == 64 | Use ==. | Ruby |
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 |
my @arr = (58,57,20); | my @arr = (58,57,20); | Correct. | Perl |
let y = 2; let y = 64; | let y = 2; y = 64; | Duplicate declaration. | JavaScript |
raise 'test' | raise Exception('test') | Raise needs an exception class. | Python |
'result' + 40 | 'result' + str(40) | Can't add int to string. | Python |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
// comment | /* comment */ | Use /* */. | CSS |
Write-Host 'world' | Write-Host 'world' | Correct. | PowerShell |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
void bar();
int main(){{bar();}} | void bar(); // prototype
int main(){{bar();}} | Declare before use. | C++ |
int* user = nullptr; *user=5; | int* user = new int; *user=5; | Allocate memory. | C++ |
name: data
age: 76 | name: data
age: 76 | Correct. | YAML |
val count = 'hello' | val count = "hello" | Double quotes. | Kotlin |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
int a = 'hello'; | String a = 'hello'; | Type mismatch. | Dart |
class = 'value' | class_name = 'value' | 'class' is a keyword. | Python |
console.log('output' | console.log('output') | Close parenthesis. | JavaScript |
'23' + 75 | 23 + 75 | Avoid string coercion. | JavaScript |
if (item) console.log('yes') else console.log('no') | if (item) console.log('yes'); else console.log('no'); | Missing semicolon. | JavaScript |
JOIN products ON users.id = products.id | JOIN products ON users.id = products.id | Correct. | SQL |
if (y = 88) | if (y == 88) | Use ==. | Scala |
y > 53 & b < 66 | y > 53 and b < 66 | Use 'and' not '&'. | Python |
foo = value | foo = 'value' | Quote strings. | Python |
num = 53 | num=53 | No spaces. | Shell |
values[67] | if (values.indices.contains(67)) values[67] | Check index. | Kotlin |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('result')); app.listen(18); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('result')); app.listen(18, () => console.log('listening')); | Add callback. | Node.js |
let index = 27; index += 1; | let mut index = 27; index += 1; | Need mut to modify. | Rust |
SELECT COUNT(*) FROM products | SELECT COUNT(*) FROM products; | Missing semicolon. | SQL |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
values(13) | if length(values) >= 13, values(13), end | Check length. | MATLAB |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
if z > 3
print('info') | if z > 3:
print('info') | Colon missing after if. | Python |
$list[67] | if ($list.Count -gt 67) {{ $list[67] }} | Check bounds. | PowerShell |
String foo = 'value'; | String foo = "value"; | Double quotes. | Java |
<a href='https://example.com' target='_blank'> | <a href='https://example.com' target='_blank' rel='noopener'> | Add rel for security. | HTML |
object Product {{ def main(args: Array[String]) = println("result") }} | object Product {{ def main(args: Array[String]): Unit = println("result") }} | Add return type Unit. | Scala |
<user name='output'/> | <user name="output"/> | Double quotes. | XML |
<p>test <b>data</p></b> | <p>test <b>data</b></p> | Nest properly. | HTML |
{{"title":"value",}} | {{"title":"value"}} | Remove trailing comma. | JSON |
title: value
id: hello, | title: value
id: hello | Remove comma. | YAML |
var x = 5; x = true | var x = 5; x = 10 | Type mismatch. | Kotlin |
#footer {{ color: #333; }} | #footer {{ color: #333; }} | Correct. | CSS |
<table><tr><td>hello<td>hello</tr></table> | <table><tr><td>hello</td><td>hello</td></tr></table> | Close td. | HTML |
if item = 14 | if item == 14 | Use ==. | Go |
div {{ color=green; }} | div {{ color: green; }} | Use colon. | CSS |
let index = 28; | let index = 28; | Correct. | JavaScript |
let b = 'result' | let b = "result" | Double quotes. | Swift |
cin >> num
cout << num; | cin >> num;
cout << num; | Add semicolon. | C++ |
{{"name":"result" "value":29}} | {{"name":"result", "value":29}} | Add comma. | JSON |
if data = 80: | if data == 80: | Use == for comparison. | Python |
let mut b=7; let ref1=&mut b; let r2=&mut b; | let mut b=7; {{ let ref1=&mut b; }} let r2=&mut b; | Only one mutable borrow. | Rust |
51b = 10 | b51 = 10 | Variable cannot start with digit. | Python |
function baz() {{
return
{{key:'output'}}
}} | function baz() {{
return {{key:'output'}};
}} | Return object on same line. | JavaScript |
if ($b = 54) {{}} | if ($b -eq 54) {{}} | Use -eq. | PowerShell |
if foo = 5 {{}} | if foo == 5 {{}} | Use ==. | Swift |
lambda x: x+1 | lambda x: x+1 | Correct lambda. | Python |
function foo(c)
print(c)
end | function foo(c)
print(c)
end | Correct. | Lua |
var x int | var x int | Correct. | Go |
a == '23' | a === 23 | Use strict equality. | JavaScript |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
let b: i32 = "info"; | let b: &str = "info"; | Type mismatch. | Rust |
function handle(): void {{ return 62; }} | function handle(): number {{ return 62; }} | Return type mismatch. | TypeScript |
handle | handle() | Add parentheses. | Swift |
print 'data' | print('data') | print needs parentheses. | Python |
[47, 100, 28 | [47, 100, 28] | Close bracket. | Ruby |
var x = 4; | var x = 4; | Correct. | Dart |
<note><desc>message</desc><desc>51</desc></note | <note><desc>message</desc><desc>51</desc></note> | Add closing >. | XML |
print 'result' | print 'result'; | Add semicolon. | Perl |
def handle
puts 'value'
end | def handle
puts 'value'
end | Correct. | Ruby |
let msg = String::from("hello"); let r=&msg; msg.push_str("!"); | let mut msg = String::from("hello"); let r=&msg; println!("{{}}", r); msg.push_str("!"); | Cannot mutate while borrowed. | Rust |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
items[84] | if items.indices.contains(84) {{ items[84] }} | Check index. | Swift |
if item = 49 | if item == 49 | Use ==. | MATLAB |
<person age=86> | <person age="86"> | Quote attribute. | XML |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
const http = require('http'); http.createServer((req,res) => res.end('world')).listen(12); | const http = require('http'); http.createServer((req,res) => res.end('world')).listen(12); | Correct. | Node.js |
function handle() {{ echo 'output'; }} | function handle() {{ echo 'output'; }} | Correct. | PHP |
String name = 'message'; | String name = 'message'; | Correct. | Dart |
<hr></hr> | <hr> | Self-closing. | HTML |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
def baz
puts 'value'
end | def baz
puts 'value'
end | Correct. | Ruby |
class Product
def method
end
end | class Product
def method
end
end | Correct. | Ruby |
String c = 'data'; | String c = "data"; | Double quotes. | Java |
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