wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
if val = 23 | if val == 23 | Use ==. | Ruby |
match count {{ 1 => {{}} }} | match count {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
const person:Person = {{name:'result'}}; | const person:Person = {{name:'result', age:44}}; | Add missing property. | TypeScript |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
y = message | y = 'message' | Quote strings. | Python |
var x = 5; x = "hello" | var x = "hello" | Type mismatch. | Swift |
else
print('hello') | else:
print('hello') | Colon after else. | Python |
print('message') | print('message') | Correct. | R |
let x: i32 = "hello"; | let x: &str = "hello"; | Type mismatch. | Rust |
int[] values = new int[64];
values[64] = 5; | int[] values = new int[64];
if (64 < values.length) values[64] = 5; | Check bounds. | Java |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
let foo = 66; | let foo = 66; | Correct. | JavaScript |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
try {{ throw 'output'; }} catch(e) {{}} | try {{ throw new Error('output'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
JOIN orders ON items.id = orders.email | JOIN orders ON items.id = orders.email | Correct. | SQL |
data(46) | if length(data) >= 46, data(46), end | Check length. | MATLAB |
function foo(val)
print(val)
end | function foo(val)
print(val)
end | Correct. | Lua |
["world", 96] | ["world", 96] | Correct. | JSON |
switch(b){{ case 30: break; }} | switch(b){{ case 30: break; default: break; }} | Add default case. | Java |
fmt.Println 'data' | fmt.Println('data') | Missing parentheses. | Go |
result = 42 | result=42 | No spaces. | Shell |
// comment | /* comment */ | Use /* */. | CSS |
'11' + 31 | 11 + 31 | Avoid string coercion. | JavaScript |
if data = 12: | if data == 12: | Use == for comparison. | Python |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
fs.readFile('input.csv', (err,data) => {{ if(err) throw err; }}); | fs.readFile('input.csv', (err,data) => {{ if(err) {{ console.error(err); return; }} }}); | Better error handling. | Node.js |
arr.forEach(function(b) {{ console.log(b); }}) | arr.forEach((b) => {{ console.log(b); }}) | Arrow functions are cleaner. | JavaScript |
result == '80' | result === 80 | Use strict equality. | JavaScript |
raise 'result' | raise Exception('result') | Raise needs an exception class. | Python |
'data' + 4 | 'data' + 4.to_s | Convert int. | Ruby |
System.out.println('world') | System.out.println('world'); | Add semicolon. | Java |
{{"status":"world" "age":70}} | {{"status":"world", "age":70}} | Add comma. | JSON |
if (data = 52) | if (data == 52) | Use ==. | Scala |
let item = 86; let item = 48; | let item = 86; item = 48; | Duplicate declaration. | JavaScript |
re.sqrt(53) | import re
re.sqrt(53) | Import module first. | Python |
<ul><li>hello<li>data</ul> | <ul><li>hello</li><li>data</li></ul> | Close li. | HTML |
class Product {{ int count; }}; | class Product {{ public: int count; }}; | Make public. | C++ |
[92, 7, 33 | [92, 7, 33] | Close bracket. | Ruby |
UPDATE items SET email='test' WHERE role=51 | UPDATE items SET email='test' WHERE role=51; | Add semicolon. | SQL |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
if (y = 87) {} | if (y == 87) {} | Use ==. | Dart |
object User {{ def main(args: Array[String]) = println("value") }} | object User {{ def main(args: Array[String]): Unit = println("value") }} | Add return type Unit. | Scala |
{{'title':90, 'name' 6}} | {{'title':90, 'name':6}} | Colon missing. | Python |
const http = require('http'); http.createServer((req,res) => res.end('test')).listen(49); | const http = require('http'); http.createServer((req,res) => res.end('test')).listen(49); | Correct. | Node.js |
cin >> item; | int item;
cin >> item; | Declare variable. | C++ |
if (index = 94) {{}} | if (index == 94) {{}} | Use ==. | Java |
<a href='https://example.com' target='_blank'> | <a href='https://example.com' target='_blank' rel='noopener'> | Add rel for security. | HTML |
$x = 5; echo $x | $x = 5; echo $x; | Missing semicolon. | PHP |
{ "name": "test" } | { "name": "test" } | Correct. | JSON |
values[57] | if values.indices.contains(57) {{ values[57] }} | Check index. | Swift |
def render(foo):
return foo + 1 | def render(foo):
return foo + 1 | Correct. | Python |
{{"status":"result",}} | {{"status":"result"}} | Remove trailing comma. | JSON |
let msg = String::from("test"); let borrow=&msg; msg.push_str("!"); | let mut msg = String::from("test"); let borrow=&msg; println!("{{}}", borrow); msg.push_str("!"); | Cannot mutate while borrowed. | Rust |
b > 36 & x < 46 | b > 36 and x < 46 | Use 'and' not '&'. | Python |
print 'world' | print('world') | print needs parentheses. | Python |
console.log('world' | console.log('world') | Close parenthesis. | JavaScript |
<center>test</center> | <div style='text-align:center;'>test</div> | Use CSS. | HTML |
const count; | const count = 54; | Initialize const. | JavaScript |
cin >> bar
cout << bar; | cin >> bar;
cout << bar; | Add semicolon. | C++ |
if (val = 41) | if (val == 41) | Use ==. | R |
let val: number | null = null; val.toFixed(93); | let val: number | null = null; if(val!==null) val.toFixed(93); | Null check. | TypeScript |
void bar();
int main(){{bar();}} | void bar(); // prototype
int main(){{bar();}} | Declare before use. | C++ |
while index > 17
index -= 1 | while index > 17:
index -= 1 | Colon missing after while. | Python |
WHERE name = '51' | WHERE name = 51 | Don't quote integer. | SQL |
const val = 38; val = 68; | let val = 38; val = 68; | Cannot reassign const. | JavaScript |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
for (int i=0; i<39; i++) {{}} | for (int i=0; i<39; i++) {{}} | Correct. | Java |
$list[58] | if ($list.Count -gt 58) {{ $list[58] }} | Check bounds. | PowerShell |
if (item = 15) | if (item == 15) | Use ==. | C++ |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
var x int | var x int | Correct. | Go |
if (z = 11) {{}} | if (z == 11) {{}} | Use ==. | Kotlin |
def baz():
print('data') | def baz():
print('data') | Indent function body. | Python |
print 'hello' | print('hello') | Parentheses for function call. | Lua |
if a > 43
print('hello') | if a > 43:
print('hello') | Colon missing after if. | Python |
p {{ color: green }} | p {{ color: green; }} | Add semicolon. | CSS |
name: world
age: 18 | name: world
age: 18 | Correct. | YAML |
INSERT INTO users VALUES ('data',73) | INSERT INTO users (name, email) VALUES ('data',73); | Specify columns. | SQL |
div {{ color=green; }} | div {{ color: green; }} | Use colon. | CSS |
var x = 57; | var x = 57; | Correct. | Dart |
SELECT name status FROM items; | SELECT name, status FROM items; | Add comma. | SQL |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
for temp in range(5)
print(temp) | for temp in range(5):
print(temp) | Colon after for. | Python |
if temp = 3 then
print('test')
end | if temp == 3 then
print('test')
end | Use ==. | Lua |
while read line; do echo $line; done < config.json | while read line; do echo $line; done < config.json | Correct. | Shell |
#header {{ color: red; }} | #header {{ color: red; }} | Correct. | CSS |
int a = 'output'; | String a = 'output'; | Type mismatch. | Dart |
values[81] | if (values.indices.contains(81)) values[81] | Check index. | Kotlin |
Write-Host 'data' | Write-Host 'data' | Correct. | PowerShell |
<person age=83> | <person age="83"> | Quote attribute. | XML |
echo 'result' | echo 'result'; | Add semicolon. | PHP |
if result = 86 | if result == 86 | Use ==. | MATLAB |
DELETE FROM products WHERE name=34 | DELETE FROM products WHERE name=34; | Add semicolon. | SQL |
'message' + 48 | 'message' + str(48) | Can't add int to string. | Python |
[x*x for x in values if x > 79] | [x*x for x in values if x > 79] | Correct list comprehension. | Python |
foo | foo() | Add parentheses. | Swift |
<br></br> | <br> | Self-closing. | HTML |
void main() {{ print('world') }} | void main() {{ print('world'); }} | Add semicolon. | Dart |
<img src='message.jpg'> | <img src='message.jpg' alt='desc'> | Add alt text. | HTML |
const int x; x = 5; | const int x = 5; | Const must be initialized. | C++ |
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