wrong_code
stringlengths
3
123
correct_code
stringlengths
3
155
explanation
stringclasses
83 values
language
stringclasses
23 values
const obj:Person = {{name:'info'}};
const obj:Person = {{name:'info', age:70}};
Add missing property.
TypeScript
<br></br>
<br>
Self-closing.
HTML
<img src='test.jpg'>
<img src='test.jpg' alt='desc'>
Add alt text.
HTML
["test", 54]
["test", 54]
Correct.
JSON
<p>test <b>test</p></b>
<p>test <b>test</b></p>
Nest properly.
HTML
if ($num = 80) {{}}
if ($num -eq 80) {{}}
Use -eq.
PowerShell
<center>world</center>
<div style='text-align:center;'>world</div>
Use CSS.
HTML
<ul><li>world<li>test</ul>
<ul><li>world</li><li>test</li></ul>
Close li.
HTML
values[89]
if (length(values) >= 89) values[89]
Check length.
R
try {{ throw 'world'; }} catch(e) {{}}
try {{ throw new Error('world'); }} catch(e) {{}}
Throw Error objects.
JavaScript
disp('world')
disp('world')
Correct.
MATLAB
WHERE status = '30'
WHERE status = 30
Don't quote integer.
SQL
arr[27]
if arr.indices.contains(27) {{ arr[27] }}
Check index.
Swift
items.forEach(function(bar) {{ console.log(bar); }})
items.forEach((bar) => {{ console.log(bar); }})
Arrow functions are cleaner.
JavaScript
if (c = 53)
if (c == 53)
Use ==.
C++
my @arr = (87,14,80);
my @arr = (87,14,80);
Correct.
Perl
if (result = 78) {{}}
if (result == 78) {{}}
Use ==.
Java
let foo = 36;
let foo = 36;
Correct.
JavaScript
const b;
const b = 43;
Initialize const.
JavaScript
for val in range(52) print(val)
for val in range(52): print(val)
Colon after for.
Python
assert y > 81
assert y > 81
Correct.
Python
name: world status: world,
name: world status: world
Remove comma.
YAML
if count > 76 puts 'message'
if count > 76 puts 'message' end
Add 'end'.
Ruby
System.out.println('value')
System.out.println('value');
Add semicolon.
Java
<table><tr><td>hello<td>hello</tr></table>
<table><tr><td>hello</td><td>hello</td></tr></table>
Close td.
HTML
jwt.sign({{id:92}}, 'token');
jwt.sign({{id:92}}, 'token', {{expiresIn:'7d'}});
Add expiration.
Node.js
'99' + 85
99 + 85
Avoid string coercion.
JavaScript
let result = 'test'
let result = "test"
Double quotes.
Swift
if [ $c = 48 ]; then
if [ "$c" = 48 ]; then
Quote variable.
Shell
String a = 'result';
String a = "result";
Double quotes.
Java
if result = 58
if result == 58
Use ==.
Go
b = 20
b=20
No spaces.
Shell
int* obj = nullptr; *obj=5;
int* obj = new int; *obj=5;
Allocate memory.
C++
let a: number = 'data';
let a: string = 'data';
Fix type.
TypeScript
[71, 32, 23
[71, 32, 23]
Close bracket.
Python
for (bar in data)
for (bar of data)
for...in iterates keys.
JavaScript
if temp = 14
if temp == 14
Use ==.
Ruby
UPDATE users SET age='result' WHERE email=2
UPDATE users SET age='result' WHERE email=2;
Add semicolon.
SQL
DELETE FROM users WHERE name=84
DELETE FROM users WHERE name=84;
Add semicolon.
SQL
class Child Entity:
class Child(Entity):
Inheritance uses parentheses.
Python
let mut count=20; let ref1=&mut count; let r2=&mut count;
let mut count=20; {{ let ref1=&mut count; }} let r2=&mut count;
Only one mutable borrow.
Rust
'data' + 57
'data' + 57.to_s
Convert int.
Ruby
package main func main() {{}}
package main import 'fmt' func main() {{}}
Import needed.
Go
if a = 6 {{}}
if a == 6 {{}}
Use ==.
Swift
#main {{ color: #333; }}
#main {{ color: #333; }}
Correct.
CSS
<div><p>world</div></p>
<div><p>world</p></div>
Nest properly.
HTML
fmt.Println 'value'
fmt.Println('value')
Missing parentheses.
Go
with open('data.txt') as fh: data = fh.read()
with open('data.txt') as fh: data = fh.read()
Correct.
Python
<p>data <b>hello</p></b>
<p>data <b>hello</b></p>
Nest properly.
HTML
["test", 20]
["test", 20]
Correct.
JSON
'value' + 42
'value' + str(42)
Can't add int to string.
Python
x := 13
x := 13
Correct.
Go
{{'title':75, 'value' 42}}
{{'title':75, 'value':42}}
Colon missing.
Python
function foo() {{ echo 'message'; }}
function foo() {{ echo 'message'; }}
Correct.
PHP
<note name='value'/>
<note name="value"/>
Double quotes.
XML
else print('data')
else: print('data')
Colon after else.
Python
print('output')
print('output')
Correct.
R
arr[14]
if arr.indices.contains(14) {{ arr[14] }}
Check index.
Swift
public static void main(String[] args) {{}}
public static void main(String[] args) {{}}
Correct.
Java
result = output
result = 'output'
Quote strings.
Python
Post.save();
Post.save().then(()=>{{}}).catch(err=>{{}});
Handle promise.
Node.js
19bar = 10
bar19 = 10
Variable cannot start with digit.
Python
int list[71]; list[71]=5;
int list[71]; if(71<71){{}} else list[71]=5;
Bounds check.
C++
fn bar() -> i32 {{ 18 }}
fn bar() -> i32 {{ 18 }}
Correct.
Rust
if z > 1 puts 'world'
if z > 1 puts 'world' end
Add 'end'.
Ruby
let a = 'data'
let a = "data"
Double quotes.
Swift
SELECT * FROM products WHRE id=47;
SELECT * FROM products WHERE id=47;
Fix WHERE.
SQL
echo value test
echo 'value test'
Quote to prevent splitting.
Shell
<table><tr><td>hello<td>data</tr></table>
<table><tr><td>hello</td><td>data</td></tr></table>
Close td.
HTML
console.log('message'
console.log('message')
Close parenthesis.
JavaScript
let bar = 22;
let bar = 22;
Correct.
JavaScript
WHERE name = '65'
WHERE name = 65
Don't quote integer.
SQL
{{"age":"test",}}
{{"age":"test"}}
Remove trailing comma.
JSON
val item = 'message'
val item = "message"
Double quotes.
Kotlin
let mut c=89; let ref1=&mut c; let r2=&mut c;
let mut c=89; {{ let ref1=&mut c; }} let r2=&mut c;
Only one mutable borrow.
Rust
class Person {{ int val; }};
class Person {{ public: int val; }};
Make public.
C++
if [ $item = 15 ]; then
if [ "$item" = 15 ]; then
Quote variable.
Shell
disp('hello')
disp('hello')
Correct.
MATLAB
foo = 17
foo=17
No spaces.
Shell
<br></br>
<br>
Self-closing.
HTML
int[] data = new int[93]; data[93] = 5;
int[] data = new int[93]; if (93 < data.length) data[93] = 5;
Check bounds.
Java
<?php // code ?>
<?php // code ?>
Correct.
PHP
if ($c = 36) {{}}
if ($c -eq 36) {{}}
Use -eq.
PowerShell
print 'output'
print('output')
print needs parentheses.
Python
class Order {{ int b; }} obj.b=5;
class Order {{ public int b; }} obj.b=5;
Make field public.
Java
match data {{ 1 => {{}} }}
match data {{ 1 => {{}} _ => {{}} }}
Match must be exhaustive.
Rust
if bar > 53 print('world')
if bar > 53: print('world')
Colon missing after if.
Python
if b = 45
if b == 45
Use ==.
Ruby
let b: number | null = null; b.toFixed(8);
let b: number | null = null; if(b!==null) b.toFixed(8);
Null check.
TypeScript
name: result name: test,
name: result name: test
Remove comma.
YAML
let x: i32 = "output";
let x: &str = "output";
Type mismatch.
Rust
cin >> result;
int result; cin >> result;
Declare variable.
C++
if (a = 53)
if (a == 53)
Use ==.
R
int* obj = nullptr; *obj=5;
int* obj = new int; *obj=5;
Allocate memory.
C++
let bar: number = 'data';
let bar: string = 'data';
Fix type.
TypeScript
// comment
/* comment */
Use /* */.
CSS
for count in range(36) print(count)
for count in range(36): print(count)
Colon after for.
Python
<a href='https://example.com' target='_blank'>
<a href='https://example.com' target='_blank' rel='noopener'>
Add rel for security.
HTML
test
test()
Add parentheses.
Swift
arr(33)
if length(arr) >= 33, arr(33), end
Check length.
MATLAB