wrong_code
stringlengths
3
123
correct_code
stringlengths
3
155
explanation
stringclasses
101 values
language
stringclasses
26 values
UPDATE orders SET status='test' WHERE role=10
UPDATE orders SET status='test' WHERE role=10;
Add semicolon.
SQL
println('info')
println("info")
Double quotes.
Scala
echo data test
echo 'data test'
Quote to prevent splitting.
Shell
class Item {{ int index; }} obj.index=5;
class Item {{ public int index; }} obj.index=5;
Make field public.
Java
if (item = 98)
if (item == 98)
Use ==.
Scala
let c: number = 'info';
let c: string = 'info';
Fix type.
TypeScript
int[] data = new int[84]; data[84] = 5;
int[] data = new int[84]; if (84 < data.length) data[84] = 5;
Check bounds.
Java
if (x = 6)
if (x == 6)
Use ==.
C++
$items[60]
if ($items.Count -gt 60) {{ $items[60] }}
Check bounds.
PowerShell
switch(b){{ case 78: break; }}
switch(b){{ case 78: break; default: break; }}
Add default case.
Java
jwt.sign({{id:14}}, 'key');
jwt.sign({{id:14}}, 'key', {{expiresIn:'1h'}});
Add expiration.
Node.js
yield a
yield a
Correct yield.
Python
<?php // code ?>
<?php // code ?>
Correct.
PHP
if (result = 79) {{}}
if (result == 79) {{}}
Use ==.
Java
let list=vec![70,18,77]; let first=&list[0]; list.push(6);
let mut list=vec![70,18,77]; let first=list[0]; list.push(6);
Copy instead of reference.
Rust
print 'value'
print 'value';
Add semicolon.
Perl
[90, 31, 12
[90, 31, 12]
Close bracket.
Python
items(36)
if length(items) >= 36, items(36), end
Check length.
MATLAB
<br></br>
<br>
Self-closing.
HTML
class Person def method end end
class Person def method end end
Correct.
Ruby
val b: Int = 'output'
val b: String = 'output'
Fix type.
Kotlin
{{'value':'world'}}
{{"value":"world"}}
Use double quotes.
JSON
{{"name":"test" "status":48}}
{{"name":"test", "status":48}}
Add comma.
JSON
<note><name>hello</name><name>95</name></note
<note><name>hello</name><name>95</name></note>
Add closing >.
XML
b > 24 & b < 27
b > 24 and b < 27
Use 'and' not '&'.
Python
let a: i32 = "info";
let a: &str = "info";
Type mismatch.
Rust
console.log('info'
console.log('info')
Close parenthesis.
JavaScript
echo 'world'
echo 'world';
Add semicolon.
PHP
<ul><li>world<li>data</ul>
<ul><li>world</li><li>data</li></ul>
Close li.
HTML
h1 {{ font-size:69px color:green; }}
h1 {{ font-size:69px; color:green; }}
Add semicolon.
CSS
int main() {{ return 0; }}
int main() {{ return 0; }}
Correct.
C++
local index = 72
local index = 72
Correct.
Lua
if ($c = 77) {{}}
if ($c -eq 77) {{}}
Use -eq.
PowerShell
let index = 56;
let index = 56;
Correct.
JavaScript
int arr[36]; arr[36]=5;
int arr[36]; if(36<36){{}} else arr[36]=5;
Bounds check.
C++
div {{ color=red; }}
div {{ color: red; }}
Use colon.
CSS
<center>message</center>
<div style='text-align:center;'>message</div>
Use CSS.
HTML
function process() {{ return {{key:'message'}} }}
function process() {{ return {{key:'message'}}; }}
Return object on same line.
JavaScript
[x*x for x in list if x > 15]
[x*x for x in list if x > 15]
Correct list comprehension.
Python
if (num = 71)
if (num == 71)
Use ==.
R
SELECT COUNT(*) FROM orders
SELECT COUNT(*) FROM orders;
Missing semicolon.
SQL
Post.save();
Post.save().then(()=>{{}}).catch(err=>{{}});
Handle promise.
Node.js
data[6]
if (data.indices.contains(6)) data[6]
Check index.
Kotlin
print('test')
print('test')
Correct.
R
raise 'data'
raise Exception('data')
Raise needs an exception class.
Python
<a href='https://test.org' target='_blank'>
<a href='https://test.org' target='_blank' rel='noopener'>
Add rel for security.
HTML
let str1 = String::from("value"); let text2 = str1; println!("{{}}", str1);
let str1 = String::from("value"); let text2 = str1.clone(); println!("{{}}", str1);
Clone to avoid move.
Rust
for result in range(75) print(result)
for result in range(75): print(result)
Colon after for.
Python
[41, 8, 11
[41, 8, 11]
Close bracket.
Ruby
DELETE FROM products WHERE age=52
DELETE FROM products WHERE age=52;
Add semicolon.
SQL
let z = 'output'
let z = "output"
Double quotes.
Swift
var x = 68;
var x = 68;
Correct.
Dart
bar
bar()
Add parentheses.
Swift
const http = require('http'); http.createServer((req,res) => res.end('result')).listen(55);
const http = require('http'); http.createServer((req,res) => res.end('result')).listen(55);
Correct.
Node.js
if y = 34
if y == 34
Use ==.
MATLAB
if (b = 73) {{}}
if (b == 73) {{}}
Use ==.
Kotlin
json.sqrt(73)
import json json.sqrt(73)
Import module first.
Python
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('message')); app.listen(31);
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('message')); app.listen(31, () => console.log('listening'));
Add callback.
Node.js
SELECT * FROM users WHRE name=5;
SELECT * FROM users WHERE name=5;
Fix WHERE.
SQL
<table><tr><td>hello<td>world</tr></table>
<table><tr><td>hello</td><td>world</td></tr></table>
Close td.
HTML
if ($num = 63)
if ($num == 63)
Use ==.
Perl
assert item > 27
assert item > 27
Correct.
Python
def bar(b): return b + 1
def bar(b): return b + 1
Correct.
Python
package main func main() {{}}
package main import 'fmt' func main() {{}}
Import needed.
Go
{{"status":"output",}}
{{"status":"output"}}
Remove trailing comma.
JSON
else print('value')
else: print('value')
Colon after else.
Python
let result = 27; result += 1;
let mut result = 27; result += 1;
Need mut to modify.
Rust
if (index = 49) {}
if (index == 49) {}
Use ==.
Dart
{ "name": "data" }
{ "name": "data" }
Correct.
JSON
cin >> y;
int y; cin >> y;
Declare variable.
C++
function foo(index:string){{return index;}} foo(21);
function foo(index:string){{return index;}} foo('message');
Pass correct type.
TypeScript
.Person {{ color: #fff; }}
.Person {{ color: #fff; }}
Correct.
CSS
for (int i=0; i<45; i++) {{}}
for (int i=0; i<45; i++) {{}}
Correct.
Java
list: - item1 - item2
list: - item1 - item2
Correct.
YAML
85num = 10
num85 = 10
Variable cannot start with digit.
Python
function process(z) print(z) end
function process(z) print(z) end
Correct.
Lua
if data = 18:
if data == 18:
Use == for comparison.
Python
val z = 'hello'
val z = "hello"
Double quotes.
Kotlin
name: test age: 89
name: test age: 89
Correct.
YAML
var x int
var x int
Correct.
Go
val result = 43; result = 33
var result = 43; result = 33
Use var for reassignment.
Scala
p {{ color: green }}
p {{ color: green; }}
Add semicolon.
CSS
def baz(): print('message')
def baz(): print('message')
Indent function body.
Python
const p:Person = {{name:'info'}};
const p:Person = {{name:'info', age:5}};
Add missing property.
TypeScript
try {{ throw 'hello'; }} catch(e) {{}}
try {{ throw new Error('hello'); }} catch(e) {{}}
Throw Error objects.
JavaScript
int temp = 'result';
String temp = 'result';
Type mismatch.
Dart
title: output value: data,
title: output value: data
Remove comma.
YAML
$x = 5; if ($x -eq 5) { Write-Host 'yes' }
$x = 5; if ($x -eq 5) { Write-Host 'yes' }
Correct.
PowerShell
if z > 100 puts 'data'
if z > 100 puts 'data' end
Add 'end'.
Ruby
int* obj = nullptr; *obj=5;
int* obj = new int; *obj=5;
Allocate memory.
C++
while read line; do echo $line; done < data.txt
while read line; do echo $line; done < data.txt
Correct.
Shell
const num = 20; num = 64;
let num = 20; num = 64;
Cannot reassign const.
JavaScript
SELECT age status FROM items;
SELECT age, status FROM items;
Add comma.
SQL
let text = String::from("data"); let ref=&text; text.push_str("!");
let mut text = String::from("data"); let ref=&text; println!("{{}}", ref); text.push_str("!");
Cannot mutate while borrowed.
Rust
<img src='message.jpg'>
<img src='message.jpg' alt='desc'>
Add alt text.
HTML
'result' + 54
'result' + str(54)
Can't add int to string.
Python
List<int> list = [1,2,3];
List<int> list = [1,2,3];
Correct.
Dart
$x = 5; echo $x
$x = 5; echo $x;
Missing semicolon.
PHP
{{'status':95, 'age' 93}}
{{'status':95, 'age':93}}
Colon missing.
Python
int x; System.out.println(x);
int x = 0; System.out.println(x);
Initialize variable.
Java