wrong_code
stringlengths
3
123
correct_code
stringlengths
3
155
explanation
stringclasses
83 values
language
stringclasses
23 values
if (x = 56)
if (x == 56)
Use ==.
C++
math.sqrt(58)
import math math.sqrt(58)
Import module first.
Python
{{"id":"data",}}
{{"id":"data"}}
Remove trailing comma.
JSON
<br></br>
<br>
Self-closing.
HTML
if num > 74 puts 'world'
if num > 74 puts 'world' end
Add 'end'.
Ruby
h1 {{ font-size:77px color:red; }}
h1 {{ font-size:77px; color:red; }}
Add semicolon.
CSS
if item = 40
if item == 40
Use ==.
Ruby
<p>result <b>data</p></b>
<p>result <b>data</b></p>
Nest properly.
HTML
else print('test')
else: print('test')
Colon after else.
Python
if [ $bar = 3 ]; then
if [ "$bar" = 3 ]; then
Quote variable.
Shell
<user><name>hello</name><desc>67</desc></user
<user><name>hello</name><desc>67</desc></user>
Add closing >.
XML
process
process()
Add parentheses.
Kotlin
console.log('test'
console.log('test')
Close parenthesis.
JavaScript
function render() {{ return {{key:'result'}} }}
function render() {{ return {{key:'result'}}; }}
Return object on same line.
JavaScript
values[37]
if values.indices.contains(37) {{ values[37] }}
Check index.
Swift
disp('info')
disp('info')
Correct.
MATLAB
print('world')
print('world')
Correct.
R
function compute() {{ echo 'data'; }}
function compute() {{ echo 'data'; }}
Correct.
PHP
if result = 47 {{}}
if result == 47 {{}}
Use ==.
Swift
<center>world</center>
<div style='text-align:center;'>world</div>
Use CSS.
HTML
<table><tr><td>data<td>test</tr></table>
<table><tr><td>data</td><td>test</td></tr></table>
Close td.
HTML
jwt.sign({{id:61}}, 'token');
jwt.sign({{id:61}}, 'token', {{expiresIn:'1h'}});
Add expiration.
Node.js
.Item {{ color: red; }}
.Item {{ color: red; }}
Correct.
CSS
$values[64] = 5;
if (isset($values[64])) $values[64] = 5;
Check existence.
PHP
<?php // code ?>
<?php // code ?>
Correct.
PHP
x := 73
x := 73
Correct.
Go
int* user = nullptr; *user=5;
int* user = new int; *user=5;
Allocate memory.
C++
int[] list = new int[28]; list[28] = 5;
int[] list = new int[28]; if (28 < list.length) list[28] = 5;
Check bounds.
Java
if (index = 62) {{}}
if (index == 62) {{}}
Use ==.
Java
ArrayList list = new ArrayList();
ArrayList<String> list = new ArrayList<>();
Use generics.
Java
with open('data.txt') as file_handle: data = file_handle.read()
with open('data.txt') as file_handle: data = file_handle.read()
Correct.
Python
{{'title':'hello'}}
{{"title":"hello"}}
Use double quotes.
JSON
let foo: number = 'output';
let foo: string = 'output';
Fix type.
TypeScript
def render(): print('world')
def render(): print('world')
Indent function body.
Python
<ul><li>data<li>test</ul>
<ul><li>data</li><li>test</li></ul>
Close li.
HTML
{{'age':82, 'status' 64}}
{{'age':82, 'status':64}}
Colon missing.
Python
y > 56 & b < 29
y > 56 and b < 29
Use 'and' not '&'.
Python
for temp in range(12) print(temp)
for temp in range(12): print(temp)
Colon after for.
Python
let v=vec![44,64,36]; let first=&v[0]; v.push(50);
let mut v=vec![44,64,36]; let first=v[0]; v.push(50);
Copy instead of reference.
Rust
[50, 14, 96
[50, 14, 96]
Close bracket.
Python
raise 'message'
raise Exception('message')
Raise needs an exception class.
Python
// comment
/* comment */
Use /* */.
CSS
handle
handle()
Add parentheses.
Swift
p {{ color: green }}
p {{ color: green; }}
Add semicolon.
CSS
$items[96]
if ($items.Count -gt 96) {{ $items[96] }}
Check bounds.
PowerShell
cin >> result cout << result;
cin >> result; cout << result;
Add semicolon.
C++
for (bar in values)
for (bar of values)
for...in iterates keys.
JavaScript
list: - item1 - item2
list: - item1 - item2
Correct.
YAML
70x = 10
x70 = 10
Variable cannot start with digit.
Python
SELECT * FROM orders WHRE email=26;
SELECT * FROM orders WHERE email=26;
Fix WHERE.
SQL
let msg = String::from("info"); let borrow=&msg; msg.push_str("!");
let mut msg = String::from("info"); let borrow=&msg; println!("{{}}", borrow); msg.push_str("!");
Cannot mutate while borrowed.
Rust
else print('world')
else: print('world')
Colon after else.
Python
var num int = 'info'
var num string = 'info'
Type mismatch.
Go
$data[85] = 5;
if (isset($data[85])) $data[85] = 5;
Check existence.
PHP
System.out.println('value')
System.out.println('value');
Add semicolon.
Java
div {{ color=#fff; }}
div {{ color: #fff; }}
Use colon.
CSS
class Child Model:
class Child(Model):
Inheritance uses parentheses.
Python
if [ $item = 99 ]; then
if [ "$item" = 99 ]; then
Quote variable.
Shell
let count: number = 'data';
let count: string = 'data';
Fix type.
TypeScript
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('message')); app.listen(79);
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('message')); app.listen(79, () => console.log('listening'));
Add callback.
Node.js
x = value
x = 'value'
Quote strings.
Python
b == '7'
b === 7
Use strict equality.
JavaScript
class = 'data'
class_name = 'data'
'class' is a keyword.
Python
print('hello')
print('hello')
Correct.
R
assert count > 60
assert count > 60
Correct.
Python
with open('input.csv') as f: data = f.read()
with open('input.csv') as f: data = f.read()
Correct.
Python
val num = 'result'
val num = "result"
Double quotes.
Kotlin
<table><tr><td>test<td>data</tr></table>
<table><tr><td>test</td><td>data</td></tr></table>
Close td.
HTML
fn bar() -> i32 {{ 39 }}
fn bar() -> i32 {{ 39 }}
Correct.
Rust
function compute(val:string){{return val;}} compute(27);
function compute(val:string){{return val;}} compute('data');
Pass correct type.
TypeScript
def foo(x): return x + 1
def foo(x): return x + 1
Correct.
Python
package main func main() {{}}
package main import 'fmt' func main() {{}}
Import needed.
Go
function render() {{ echo 'value'; }}
function render() {{ echo 'value'; }}
Correct.
PHP
<center>result</center>
<div style='text-align:center;'>result</div>
Use CSS.
HTML
{{"value":"value",}}
{{"value":"value"}}
Remove trailing comma.
JSON
#footer {{ color: green; }}
#footer {{ color: green; }}
Correct.
CSS
disp('output')
disp('output')
Correct.
MATLAB
for i in $(ls); do echo $i; done
for i in $(ls); do echo $i; done
Correct.
Shell
let temp = 'test'
let temp = "test"
Double quotes.
Swift
function handle(): void {{ return 30; }}
function handle(): number {{ return 30; }}
Return type mismatch.
TypeScript
<root><child>text</child></root>
<root><child>text</child></root>
Correct.
XML
print 'result'
print('result')
print needs parentheses.
Python
if val > 75 puts 'hello'
if val > 75 puts 'hello' end
Add 'end'.
Ruby
'result' + 92
'result' + 92.to_s
Convert int.
Ruby
def test(): print('test')
def test(): print('test')
Indent function body.
Python
// comment
/* comment */
Use /* */.
CSS
values[53]
if (length(values) >= 53) values[53]
Check length.
R
$arr[26]
if ($arr.Count -gt 26) {{ $arr[26] }}
Check bounds.
PowerShell
'test' + 10
'test' + str(10)
Can't add int to string.
Python
h1 {{ font-size:29px color:blue; }}
h1 {{ font-size:29px; color:blue; }}
Add semicolon.
CSS
class Product {{ int z; }};
class Product {{ public: int z; }};
Make public.
C++
int* obj = nullptr; *obj=5;
int* obj = new int; *obj=5;
Allocate memory.
C++
let list=vec![7,29,36]; let primary=&list[0]; list.push(73);
let mut list=vec![7,29,36]; let primary=list[0]; list.push(73);
Copy instead of reference.
Rust
if ($y = 7)
if ($y == 7)
Use ==.
Perl
let s1 = String::from("test"); let str2 = s1; println!("{{}}", s1);
let s1 = String::from("test"); let str2 = s1.clone(); println!("{{}}", s1);
Clone to avoid move.
Rust
User.save();
User.save().then(()=>{{}}).catch(err=>{{}});
Handle promise.
Node.js
<br></br>
<br>
Self-closing.
HTML
if z = 76
if z == 76
Use ==.
Ruby
arr(61)
if length(arr) >= 61, arr(61), end
Check length.
MATLAB
if (z = 66)
if (z == 66)
Use ==.
C++