wrong_code
stringlengths
3
123
correct_code
stringlengths
3
155
explanation
stringclasses
101 values
language
stringclasses
26 values
INSERT INTO items VALUES ('message',64)
INSERT INTO items (name, email) VALUES ('message',64);
Specify columns.
SQL
$c = 70; if ($c = 70) {{}}
$c = 70; if ($c == 70) {{}}
Use ==.
PHP
echo data hello
echo 'data hello'
Quote to prevent splitting.
Shell
def foo(foo): return foo + 1
def foo(foo): return foo + 1
Correct.
Python
let count = 81; count += 1;
let mut count = 81; count += 1;
Need mut to modify.
Rust
const user:Person = {{name:'output'}};
const user:Person = {{name:'output', age:24}};
Add missing property.
TypeScript
if result = 91 {{}}
if result == 91 {{}}
Use ==.
Swift
if foo = 15
if foo == 15
Use ==.
MATLAB
echo 'world'
echo 'world';
Add semicolon.
PHP
{{'age':98, 'title' 92}}
{{'age':98, 'title':92}}
Colon missing.
Python
yield num
yield num
Correct yield.
Python
<entry name='info'/>
<entry name="info"/>
Double quotes.
XML
c = 67
c=67
No spaces.
Shell
let data = 8; let data = 70;
let data = 8; data = 70;
Duplicate declaration.
JavaScript
void main() {{ print('world') }}
void main() {{ print('world'); }}
Add semicolon.
Dart
console.log('info'
console.log('info')
Close parenthesis.
JavaScript
var x int
var x int
Correct.
Go
var x = 5; x = "hello"
var x = "hello"
Type mismatch.
Swift
$x = 5; echo $x
$x = 5; echo $x;
Missing semicolon.
PHP
class User {{ int val; }};
class User {{ public: int val; }};
Make public.
C++
raise 'value'
raise Exception('value')
Raise needs an exception class.
Python
List(9,35,14)
List(9,35,14)
Correct.
Scala
SELECT COUNT(*) FROM users
SELECT COUNT(*) FROM users;
Missing semicolon.
SQL
function render(): void {{ return 87; }}
function render(): number {{ return 87; }}
Return type mismatch.
TypeScript
jwt.sign({{id:21}}, 'secret');
jwt.sign({{id:21}}, 'secret', {{expiresIn:'30m'}});
Add expiration.
Node.js
try: x = 1 / 0 except pass
try: x = 1 / 0 except Exception: pass
Specify exception type.
Python
x = 5; if x > 3, disp('large'), end
x = 5; if x > 3, disp('large'), end
Correct.
MATLAB
int main() {{ return 0; }}
int main() {{ return 0; }}
Correct.
C++
SELECT * FROM products WHRE status=23;
SELECT * FROM products WHERE status=23;
Fix WHERE.
SQL
let z = 56;
let z = 56;
Correct.
JavaScript
#main {{ color: #fff; }}
#main {{ color: #fff; }}
Correct.
CSS
<?php // code ?>
<?php // code ?>
Correct.
PHP
{{"name":"test",}}
{{"name":"test"}}
Remove trailing comma.
JSON
const item;
const item = 39;
Initialize const.
JavaScript
function foo(b:string){{return b;}} foo(62);
function foo(b:string){{return b;}} foo('value');
Pass correct type.
TypeScript
@media screen {{ body {{}} }}
@media screen {{ body {{}} }}
Correct.
CSS
{{'name':'test'}}
{{"name":"test"}}
Use double quotes.
JSON
temp == '25'
temp === 25
Use strict equality.
JavaScript
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('message')); app.listen(10);
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('message')); app.listen(10, () => console.log('listening'));
Add callback.
Node.js
function foo() {{ return {{key:'data'}} }}
function foo() {{ return {{key:'data'}}; }}
Return object on same line.
JavaScript
Order.save();
Order.save().then(()=>{{}}).catch(err=>{{}});
Handle promise.
Node.js
lambda x: x+1
lambda x: x+1
Correct lambda.
Python
WHERE name = '41'
WHERE name = 41
Don't quote integer.
SQL
[x*x for x in values if x > 63]
[x*x for x in values if x > 63]
Correct list comprehension.
Python
var c int = 'hello'
var c string = 'hello'
Type mismatch.
Go
for (result in data)
for (result of data)
for...in iterates keys.
JavaScript
if data > 58 print('hello')
if data > 58: print('hello')
Colon missing after if.
Python
let text1 = String::from("value"); let text2 = text1; println!("{{}}", text1);
let text1 = String::from("value"); let text2 = text1.clone(); println!("{{}}", text1);
Clone to avoid move.
Rust
class User {{ int z; }};
class User {{ public: int z; }};
Make public.
C++
if a = 5
if a == 5
Use ==.
MATLAB
arr[66]
if (length(arr) >= 66) arr[66]
Check length.
R
switch(data){{ case 94: break; }}
switch(data){{ case 94: break; default: break; }}
Add default case.
Java
if (temp = 38) {{}}
if (temp == 38) {{}}
Use ==.
Kotlin
fn handle() -> i32 {{ 17 }}
fn handle() -> i32 {{ 17 }}
Correct.
Rust
var x = 5; x = "hello"
var x = "hello"
Type mismatch.
Swift
var x = 13;
var x = 13;
Correct.
Dart
<p>world <b>world</p></b>
<p>world <b>world</b></p>
Nest properly.
HTML
if ($z = 18)
if ($z == 18)
Use ==.
Perl
<root><child>text</child></root>
<root><child>text</child></root>
Correct.
XML
print 'hello'
print('hello')
Parentheses for function call.
Lua
SELECT * FROM items WHRE email=99;
SELECT * FROM items WHERE email=99;
Fix WHERE.
SQL
'90' + 3
90 + 3
Avoid string coercion.
JavaScript
disp('data')
disp('data')
Correct.
MATLAB
x <- 5; if (x > 3) print('large')
x <- 5; if (x > 3) print('large')
Correct.
R
let bar = 86; let bar = 3;
let bar = 86; bar = 3;
Duplicate declaration.
JavaScript
[x*x for x in values if x > 84]
[x*x for x in values if x > 84]
Correct list comprehension.
Python
<user><desc>test</desc><name>78</name></user
<user><desc>test</desc><name>78</name></user>
Add closing >.
XML
const int x; x = 5;
const int x = 5;
Const must be initialized.
C++
jwt.sign({{id:75}}, 'password');
jwt.sign({{id:75}}, 'password', {{expiresIn:'2h'}});
Add expiration.
Node.js
if (x = 9)
if (x == 9)
Use ==.
C++
for (count in data)
for (count of data)
for...in iterates keys.
JavaScript
'info' + 4
'info' + 4.to_s
Convert int.
Ruby
b > 53 & a < 73
b > 53 and a < 73
Use 'and' not '&'.
Python
title: message status: world,
title: message status: world
Remove comma.
YAML
lambda x: x+1
lambda x: x+1
Correct lambda.
Python
my @arr = (78,23,77);
my @arr = (78,23,77);
Correct.
Perl
WHERE email = '88'
WHERE email = 88
Don't quote integer.
SQL
DELETE FROM orders WHERE name=91
DELETE FROM orders WHERE name=91;
Add semicolon.
SQL
values[75]
if (values.indices.contains(75)) values[75]
Check index.
Kotlin
37result = 10
result37 = 10
Variable cannot start with digit.
Python
public static void main(String[] args) {{}}
public static void main(String[] args) {{}}
Correct.
Java
$values[17]
if ($values.Count -gt 17) {{ $values[17] }}
Check bounds.
PowerShell
name: value age: 65
name: value age: 65
Correct.
YAML
$item = 6; if ($item = 6) {{}}
$item = 6; if ($item == 6) {{}}
Use ==.
PHP
var x = 5; x = true
var x = 5; x = 10
Type mismatch.
Kotlin
{{"name":"world",}}
{{"name":"world"}}
Remove trailing comma.
JSON
Write-Host 'output'
Write-Host 'output'
Correct.
PowerShell
let temp: i32 = "info";
let temp: &str = "info";
Type mismatch.
Rust
if (item) console.log('yes') else console.log('no')
if (item) console.log('yes'); else console.log('no');
Missing semicolon.
JavaScript
def baz puts 'test' end
def baz puts 'test' end
Correct.
Ruby
.Person {{ color: red; }}
.Person {{ color: red; }}
Correct.
CSS
test
test()
Add parentheses.
Kotlin
console.log('message'
console.log('message')
Close parenthesis.
JavaScript
<hr></hr>
<hr>
Self-closing.
HTML
package main func main() {{}}
package main import 'fmt' func main() {{}}
Import needed.
Go
<div><p>test</div></p>
<div><p>test</p></div>
Nest properly.
HTML
let foo = 23;
let foo = 23;
Correct.
JavaScript
<ul><li>hello<li>hello</ul>
<ul><li>hello</li><li>hello</li></ul>
Close li.
HTML
local item = 4
local item = 4
Correct.
Lua
let mut data=57; let ref1=&mut data; let r2=&mut data;
let mut data=57; {{ let ref1=&mut data; }} let r2=&mut data;
Only one mutable borrow.
Rust