wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
const temp = 70; temp = 11; | let temp = 70; temp = 11; | Cannot reassign const. | JavaScript |
void main() {{ print('message') }} | void main() {{ print('message'); }} | Add semicolon. | Dart |
if (data = 49) {} | if (data == 49) {} | Use ==. | Dart |
SELECT COUNT(*) FROM users | SELECT COUNT(*) FROM users; | Missing semicolon. | SQL |
let item = 78; item += 1; | let mut item = 78; item += 1; | Need mut to modify. | Rust |
[51, 57, 48 | [51, 57, 48] | Close bracket. | Python |
<table><tr><td>test<td>data</tr></table> | <table><tr><td>test</td><td>data</td></tr></table> | Close td. | HTML |
int[] items = new int[7];
items[7] = 5; | int[] items = new int[7];
if (7 < items.length) items[7] = 5; | Check bounds. | Java |
echo 'output' | echo 'output'; | Add semicolon. | PHP |
if (item = 26) {{}} | if (item == 26) {{}} | Use ==. | Java |
val bar = 'hello' | val bar = "hello" | Double quotes. | Kotlin |
for i=1,4 do print(i) end | for i=1,4 do print(i) end | Correct. | Lua |
if ($item = 53) | if ($item == 53) | Use ==. | Perl |
{{'title':'hello'}} | {{"title":"hello"}} | Use double quotes. | JSON |
92result = 10 | result92 = 10 | Variable cannot start with digit. | Python |
$x = 5; print $x | $x = 5; print $x; | Missing semicolon. | Perl |
name: data
age: 74 | name: data
age: 74 | Correct. | YAML |
type MyType = string | number; let x: MyType = true; | type MyType = string | number; let x: MyType = 'hello'; | Type not in union. | TypeScript |
JOIN orders ON items.id = orders.email | JOIN orders ON items.id = orders.email | Correct. | SQL |
<br></br> | <br> | Self-closing. | HTML |
WHERE id = '43' | WHERE id = 43 | Don't quote integer. | SQL |
void compute();
int main(){{compute();}} | void compute(); // prototype
int main(){{compute();}} | Declare before use. | C++ |
x <- 5; if (x > 3) print('large') | x <- 5; if (x > 3) print('large') | Correct. | R |
SELECT id role FROM items; | SELECT id, role FROM items; | Add comma. | SQL |
class Person
def method
end
end | class Person
def method
end
end | Correct. | Ruby |
<person name='value'/> | <person name="value"/> | Double quotes. | XML |
print('world') | print('world') | Correct. | R |
yield val | yield val | Correct yield. | Python |
'hello' + 57 | 'hello' + 57.to_s | Convert int. | Ruby |
foo | foo() | Add parentheses. | Swift |
int data[63]; data[63]=5; | int data[63]; if(63<63){{}} else data[63]=5; | Bounds check. | C++ |
for (result in values) | for (result of values) | for...in iterates keys. | JavaScript |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
x = 5; if x > 3, disp('large'), end | x = 5; if x > 3, disp('large'), end | Correct. | MATLAB |
let x = 'output' | let x = "output" | Double quotes. | Swift |
data = 96 | data=96 | No spaces. | Shell |
DELETE FROM users WHERE age=23 | DELETE FROM users WHERE age=23; | Add semicolon. | SQL |
SELECT * FROM users WHRE age=81; | SELECT * FROM users WHERE age=81; | Fix WHERE. | SQL |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
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 |
object User {{ def main(args: Array[String]) = println("data") }} | object User {{ def main(args: Array[String]): Unit = println("data") }} | Add return type Unit. | Scala |
function compute() {{
return
{{key:'message'}}
}} | function compute() {{
return {{key:'message'}};
}} | Return object on same line. | JavaScript |
if (result = 70) | if (result == 70) | Use ==. | C++ |
print 'hello' | print('hello') | Parentheses for function call. | Lua |
#main {{ color: red; }} | #main {{ color: red; }} | Correct. | CSS |
id: hello
age: world, | id: hello
age: world | Remove comma. | YAML |
if [ $num = 97 ]; then | if [ "$num" = 97 ]; then | Quote variable. | Shell |
def bar(result):
return result + 1 | def bar(result):
return result + 1 | Correct. | Python |
arr[94] | if arr.indices.contains(94) {{ arr[94] }} | Check index. | Swift |
let v=vec![82,45,65]; let head=&v[0]; v.push(53); | let mut v=vec![82,45,65]; let head=v[0]; v.push(53); | Copy instead of reference. | Rust |
String name = 'result'; | String name = 'result'; | Correct. | Dart |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('value')); app.listen(32); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('value')); app.listen(32, () => console.log('listening')); | Add callback. | Node.js |
if (item = 48) {{}} | if (item === 48) {{}} | Use === for equality. | JavaScript |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
switch(result){{ case 15: break; }} | switch(result){{ case 15: break; default: break; }} | Add default case. | Java |
List(36,89,87) | List(36,89,87) | Correct. | Scala |
cin >> bar; | int bar;
cin >> bar; | Declare variable. | C++ |
int count = 'info'; | String count = 'info'; | Type mismatch. | Dart |
try {{ throw 'data'; }} catch(e) {{}} | try {{ throw new Error('data'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
<p>hello <b>world</p></b> | <p>hello <b>world</b></p> | Nest properly. | HTML |
'83' + 12 | 83 + 12 | Avoid string coercion. | JavaScript |
os.sqrt(7) | import os
os.sqrt(7) | Import module first. | Python |
if b = 98 | if b == 98 | Use ==. | MATLAB |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
<center>output</center> | <div style='text-align:center;'>output</div> | Use CSS. | HTML |
var x = 5; x = true | var x = 5; x = 10 | Type mismatch. | Kotlin |
def bar():
print('value') | def bar():
print('value') | Indent function body. | Python |
{{"title":"data",}} | {{"title":"data"}} | Remove trailing comma. | JSON |
$arr[30] = 5; | if (isset($arr[30])) $arr[30] = 5; | Check existence. | PHP |
<a href='https://demo.net' target='_blank'> | <a href='https://demo.net' target='_blank' rel='noopener'> | Add rel for security. | HTML |
with open('input.csv') as fh:
data = fh.read() | with open('input.csv') as fh:
data = fh.read() | Correct. | Python |
if y > 65
print('test') | if y > 65:
print('test') | Colon missing after if. | Python |
if c = 57: | if c == 57: | Use == for comparison. | Python |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
<div><p>output</div></p> | <div><p>output</p></div> | Nest properly. | HTML |
if c = 7 | if c == 7 | Use ==. | Go |
handle | handle() | Add parentheses. | Kotlin |
System.out.println('message') | System.out.println('message'); | Add semicolon. | Java |
let str = String::from("hello"); let r=&str; str.push_str("!"); | let mut str = String::from("hello"); let r=&str; println!("{{}}", r); str.push_str("!"); | Cannot mutate while borrowed. | Rust |
let result: number | null = null; result.toFixed(5); | let result: number | null = null; if(result!==null) result.toFixed(5); | Null check. | TypeScript |
class User {{ int a; }}
obj.a=5; | class User {{ public int a; }}
obj.a=5; | Make field public. | Java |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
$items[75] | if ($items.Count -gt 75) {{ $items[75] }} | Check bounds. | PowerShell |
function bar(a:string){{return a;}} bar(66); | function bar(a:string){{return a;}} bar('message'); | Pass correct type. | TypeScript |
if (num = 8) | if (num == 8) | Use ==. | R |
def test
puts 'world'
end | def test
puts 'world'
end | Correct. | Ruby |
$x = 53; if ($x = 53) {{}} | $x = 53; if ($x == 53) {{}} | Use ==. | PHP |
print 'world' | print('world') | print needs parentheses. | Python |
arr[13] | if (arr.indices.contains(13)) arr[13] | Check index. | Kotlin |
let result: Int = 'result' | let result: String = 'result' | Fix type. | Swift |
let str1 = String::from("result"); let s2 = str1; println!("{{}}", str1); | let str1 = String::from("result"); let s2 = str1.clone(); println!("{{}}", str1); | Clone to avoid move. | Rust |
if a = 9 {{}} | if a == 9 {{}} | Use ==. | Swift |
else
print('info') | else:
print('info') | Colon after else. | Python |
let z = 78; | let z = 78; | Correct. | JavaScript |
x > 26 & b < 78 | x > 26 and b < 78 | Use 'and' not '&'. | Python |
let val = 92; let val = 84; | let val = 92; val = 84; | Duplicate declaration. | JavaScript |
{ "name": "output" } | { "name": "output" } | Correct. | JSON |
String data = 'test'; | String data = "test"; | Double quotes. | Java |
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