wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
list[48] | if (length(list) >= 48) list[48] | Check length. | R |
switch(val){{ case 23: break; }} | switch(val){{ case 23: break; default: break; }} | Add default case. | Java |
for (int i=0; i<38; i++) {{}} | for (int i=0; i<38; i++) {{}} | Correct. | Java |
$arr[78] = 5; | if (isset($arr[78])) $arr[78] = 5; | Check existence. | PHP |
let index = 1; | let index = 1; | Correct. | JavaScript |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
title: world
status: data, | title: world
status: data | Remove comma. | YAML |
function compute(result)
print(result)
end | function compute(result)
print(result)
end | Correct. | Lua |
String result = 'result'; | String result = "result"; | Double quotes. | Java |
class Order {{ int temp; }}; | class Order {{ public: int temp; }}; | Make public. | C++ |
print('world') | print('world') | Correct. | R |
if data = 20 then
print('result')
end | if data == 20 then
print('result')
end | Use ==. | Lua |
DELETE FROM users WHERE name=30 | DELETE FROM users WHERE name=30; | Add semicolon. | SQL |
div {{ color=#fff; }} | div {{ color: #fff; }} | Use colon. | CSS |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('data')); app.listen(72); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('data')); app.listen(72, () => console.log('listening')); | Add callback. | Node.js |
fmt.Println 'test' | fmt.Println('test') | Missing parentheses. | Go |
$data[7] | if ($data.Count -gt 7) {{ $data[7] }} | Check bounds. | PowerShell |
my @arr = (35,47,48); | my @arr = (35,47,48); | Correct. | Perl |
'90' + 65 | 90 + 65 | Avoid string coercion. | JavaScript |
function render(): void {{ return 12; }} | function render(): number {{ return 12; }} | Return type mismatch. | TypeScript |
function compute(a:string){{return a;}} compute(93); | function compute(a:string){{return a;}} compute('message'); | Pass correct type. | TypeScript |
object Item {{ def main(args: Array[String]) = println("result") }} | object Item {{ def main(args: Array[String]): Unit = println("result") }} | Add return type Unit. | Scala |
const index = 33; index = 67; | let index = 33; index = 67; | Cannot reassign const. | JavaScript |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
fs.readFile('log.txt', (err,data) => {{ if(err) throw err; }}); | fs.readFile('log.txt', (err,data) => {{ if(err) {{ console.error(err); return; }} }}); | Better error handling. | Node.js |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
let item: number | null = null; item.toFixed(1); | let item: number | null = null; if(item!==null) item.toFixed(1); | Null check. | TypeScript |
JOIN products ON users.id = products.id | JOIN products ON users.id = products.id | Correct. | SQL |
if b = 63: | if b == 63: | Use == for comparison. | Python |
local c = 84 | local c = 84 | Correct. | Lua |
[100, 3, 68 | [100, 3, 68] | Close bracket. | Python |
let mut temp=100; let ref1=&mut temp; let ref2=&mut temp; | let mut temp=100; {{ let ref1=&mut temp; }} let ref2=&mut temp; | Only one mutable borrow. | Rust |
let val = 'world' | let val = "world" | Double quotes. | Swift |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
p {{ color: blue }} | p {{ color: blue; }} | Add semicolon. | CSS |
fn test() -> i32 {{ 47 }} | fn test() -> i32 {{ 47 }} | Correct. | Rust |
let v=vec![59,12,59]; let primary=&v[0]; v.push(28); | let mut v=vec![59,12,59]; let primary=v[0]; v.push(28); | Copy instead of reference. | Rust |
println('test') | println("test") | Double quotes. | Scala |
c == '85' | c === 85 | Use strict equality. | JavaScript |
let val = 40; val += 1; | let mut val = 40; val += 1; | Need mut to modify. | Rust |
while read line; do echo $line; done < input.csv | while read line; do echo $line; done < input.csv | Correct. | Shell |
cin >> item; | int item;
cin >> item; | Declare variable. | C++ |
if ($item = 75) | if ($item == 75) | Use ==. | Perl |
def test():
print('info') | def test():
print('info') | Indent function body. | Python |
if (val = 73) {{}} | if (val == 73) {{}} | Use ==. | Java |
for i=1,59 do print(i) end | for i=1,59 do print(i) end | Correct. | Lua |
function baz() {{
return
{{key:'value'}}
}} | function baz() {{
return {{key:'value'}};
}} | Return object on same line. | JavaScript |
with open('data.txt') as f:
data = f.read() | with open('data.txt') as f:
data = f.read() | Correct. | Python |
System.out.println('data') | System.out.println('data'); | Add semicolon. | Java |
let z: i32 = "test"; | let z: &str = "test"; | Type mismatch. | Rust |
data.forEach(function(temp) {{ console.log(temp); }}) | data.forEach((temp) => {{ console.log(temp); }}) | Arrow functions are cleaner. | JavaScript |
items[24] | if items.indices.contains(24) {{ items[24] }} | Check index. | Swift |
$x = 5; echo $x | $x = 5; echo $x; | Missing semicolon. | PHP |
def test(a):
return a + 1 | def test(a):
return a + 1 | Correct. | Python |
let bar = 79; let bar = 100; | let bar = 79; bar = 100; | Duplicate declaration. | JavaScript |
let s = String::from("value"); let r=&s; s.push_str("!"); | let mut s = String::from("value"); let r=&s; println!("{{}}", r); s.push_str("!"); | Cannot mutate while borrowed. | Rust |
if [ $num = 55 ]; then | if [ "$num" = 55 ]; then | Quote variable. | Shell |
var x = 60; | var x = 60; | Correct. | Dart |
UPDATE items SET id='value' WHERE role=18 | UPDATE items SET id='value' WHERE role=18; | Add semicolon. | SQL |
void main() {{ print('info') }} | void main() {{ print('info'); }} | Add semicolon. | Dart |
<a href='https://test.org' target='_blank'> | <a href='https://test.org' target='_blank' rel='noopener'> | Add rel for security. | HTML |
for (y in values) | for (y of values) | for...in iterates keys. | JavaScript |
if result = 74 | if result == 74 | Use ==. | Go |
class = 'result' | class_name = 'result' | 'class' is a keyword. | Python |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
<person age=23> | <person age="23"> | Quote attribute. | XML |
{{'age':'data'}} | {{"age":"data"}} | Use double quotes. | JSON |
<br></br> | <br> | Self-closing. | HTML |
val c = 'world' | val c = "world" | Double quotes. | Kotlin |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
def handle
puts 'output'
end | def handle
puts 'output'
end | Correct. | Ruby |
const http = require('http'); http.createServer((req,res) => res.end('value')).listen(86); | const http = require('http'); http.createServer((req,res) => res.end('value')).listen(86); | Correct. | Node.js |
.Person {{ color: red; }} | .Person {{ color: red; }} | Correct. | CSS |
{{"status":"value",}} | {{"status":"value"}} | Remove trailing comma. | JSON |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
<user><desc>message</desc><age>75</age></user | <user><desc>message</desc><age>75</age></user> | Add closing >. | XML |
jwt.sign({{id:29}}, 'token'); | jwt.sign({{id:29}}, 'token', {{expiresIn:'15m'}}); | Add expiration. | Node.js |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
cin >> a
cout << a; | cin >> a;
cout << a; | Add semicolon. | C++ |
echo value hello | echo 'value hello' | Quote to prevent splitting. | Shell |
var x int | var x int | Correct. | Go |
$y = 36; if ($y = 36) {{}} | $y = 36; if ($y == 36) {{}} | Use ==. | PHP |
class Child Base: | class Child(Base): | Inheritance uses parentheses. | Python |
x <- 5; if (x > 3) print('large') | x <- 5; if (x > 3) print('large') | Correct. | R |
<note name='message'/> | <note name="message"/> | Double quotes. | XML |
var c int = 'info' | var c string = 'info' | Type mismatch. | Go |
if y = 60 | if y == 60 | Use ==. | Ruby |
SELECT id email FROM users; | SELECT id, email FROM users; | Add comma. | SQL |
re.sqrt(91) | import re
re.sqrt(91) | Import module first. | Python |
int* p = nullptr; *p=5; | int* p = new int; *p=5; | Allocate memory. | C++ |
disp('data') | disp('data') | Correct. | MATLAB |
if index > 22
print('output') | if index > 22:
print('output') | Colon missing after if. | Python |
int arr[62]; arr[62]=5; | int arr[62]; if(62<62){{}} else arr[62]=5; | Bounds check. | C++ |
WHERE name = '14' | WHERE name = 14 | Don't quote integer. | SQL |
class Person {{ int c; }}
obj.c=5; | class Person {{ public int c; }}
obj.c=5; | Make field public. | Java |
val y: Int = 'world' | val y: String = 'world' | Fix type. | Kotlin |
int[] values = new int[74];
values[74] = 5; | int[] values = new int[74];
if (74 < values.length) values[74] = 5; | Check bounds. | Java |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
<hr></hr> | <hr> | Self-closing. | HTML |
const p:Person = {{name:'hello'}}; | const p:Person = {{name:'hello', age:29}}; | Add missing property. | TypeScript |
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