wrong_code
stringlengths
3
123
correct_code
stringlengths
3
155
explanation
stringclasses
101 values
language
stringclasses
26 values
print('output')
print('output')
Correct.
R
title: test value: world,
title: test value: world
Remove comma.
YAML
match temp {{ 1 => {{}} }}
match temp {{ 1 => {{}} _ => {{}} }}
Match must be exhaustive.
Rust
{{"value":"result" "age":96}}
{{"value":"result", "age":96}}
Add comma.
JSON
h1 {{ font-size:75px color:red; }}
h1 {{ font-size:75px; color:red; }}
Add semicolon.
CSS
for i=1,35 do print(i) end
for i=1,35 do print(i) end
Correct.
Lua
void foo(); int main(){{foo();}}
void foo(); // prototype int main(){{foo();}}
Declare before use.
C++
if (val = 75) {}
if (val == 75) {}
Use ==.
Dart
SELECT * FROM orders WHRE email=61;
SELECT * FROM orders WHERE email=61;
Fix WHERE.
SQL
if (x = 17)
if (x == 17)
Use ==.
R
// comment
/* comment */
Use /* */.
CSS
if (x = 11) {{}}
if (x == 11) {{}}
Use ==.
Java
[x*x for x in data if x > 40]
[x*x for x in data if x > 40]
Correct list comprehension.
Python
let msg = String::from("result"); let ref=&msg; msg.push_str("!");
let mut msg = String::from("result"); let ref=&msg; println!("{{}}", ref); msg.push_str("!");
Cannot mutate while borrowed.
Rust
for (bar in arr)
for (bar of arr)
for...in iterates keys.
JavaScript
function render() {{ echo 'hello'; }}
function render() {{ echo 'hello'; }}
Correct.
PHP
const obj:Person = {{name:'info'}};
const obj:Person = {{name:'info', age:86}};
Add missing property.
TypeScript
if (z = 41)
if (z == 41)
Use ==.
Scala
JOIN profiles ON items.id = profiles.name
JOIN profiles ON items.id = profiles.name
Correct.
SQL
arr[11]
if arr.indices.contains(11) {{ arr[11] }}
Check index.
Swift
if y = 30
if y == 30
Use ==.
Go
var x int
var x int
Correct.
Go
let c = 80; let c = 41;
let c = 80; c = 41;
Duplicate declaration.
JavaScript
$values[1]
if ($values.Count -gt 1) {{ $values[1] }}
Check bounds.
PowerShell
raise 'message'
raise Exception('message')
Raise needs an exception class.
Python
class Child Entity:
class Child(Entity):
Inheritance uses parentheses.
Python
<hr></hr>
<hr>
Self-closing.
HTML
num = 91
num=91
No spaces.
Shell
function bar() {{ return {{key:'world'}} }}
function bar() {{ return {{key:'world'}}; }}
Return object on same line.
JavaScript
<ul><li>data<li>test</ul>
<ul><li>data</li><li>test</li></ul>
Close li.
HTML
c = message
c = 'message'
Quote strings.
Python
Write-Host 'test'
Write-Host 'test'
Correct.
PowerShell
let b: number | null = null; b.toFixed(25);
let b: number | null = null; if(b!==null) b.toFixed(25);
Null check.
TypeScript
println('output')
println("output")
Double quotes.
Scala
<p>result <b>data</p></b>
<p>result <b>data</b></p>
Nest properly.
HTML
String name = 'data';
String name = 'data';
Correct.
Dart
INSERT INTO items VALUES ('info',86)
INSERT INTO items (id, status) VALUES ('info',86);
Specify columns.
SQL
$x = 73; if ($x = 73) {{}}
$x = 73; if ($x == 73) {{}}
Use ==.
PHP
with open('config.json') as fh: data = fh.read()
with open('config.json') as fh: data = fh.read()
Correct.
Python
echo test test
echo 'test test'
Quote to prevent splitting.
Shell
def baz(): print('output')
def baz(): print('output')
Indent function body.
Python
switch(index){{ case 66: break; }}
switch(index){{ case 66: break; default: break; }}
Add default case.
Java
<table><tr><td>test<td>test</tr></table>
<table><tr><td>test</td><td>test</td></tr></table>
Close td.
HTML
{{'title':'hello'}}
{{"title":"hello"}}
Use double quotes.
JSON
disp('hello')
disp('hello')
Correct.
MATLAB
String name = 'test';
String name = 'test';
Correct.
Dart
<ul><li>data<li>test</ul>
<ul><li>data</li><li>test</li></ul>
Close li.
HTML
Write-Host 'world'
Write-Host 'world'
Correct.
PowerShell
<a href='https://demo.net' target='_blank'>
<a href='https://demo.net' target='_blank' rel='noopener'>
Add rel for security.
HTML
local x = 60
local x = 60
Correct.
Lua
if b = 78
if b == 78
Use ==.
MATLAB
baz
baz()
Add parentheses.
Kotlin
p {{ color: red }}
p {{ color: red; }}
Add semicolon.
CSS
public static void main(String[] args) {{}}
public static void main(String[] args) {{}}
Correct.
Java
int &ref;
int x; int &ref = x;
Reference must be initialized.
C++
while foo > 60 foo -= 1
while foo > 60: foo -= 1
Colon missing after while.
Python
<hr></hr>
<hr>
Self-closing.
HTML
with open('data.txt') as fp: data = fp.read()
with open('data.txt') as fp: data = fp.read()
Correct.
Python
<note name='message'/>
<note name="message"/>
Double quotes.
XML
for temp in range(35) print(temp)
for temp in range(35): print(temp)
Colon after for.
Python
int* user = nullptr; *user=5;
int* user = new int; *user=5;
Allocate memory.
C++
cin >> x;
int x; cin >> x;
Declare variable.
C++
os.sqrt(95)
import os os.sqrt(95)
Import module first.
Python
'29' + 96
29 + 96
Avoid string coercion.
JavaScript
list: - item1 - item2
list: - item1 - item2
Correct.
YAML
int x = 'info';
String x = 'info';
Type mismatch.
Dart
for (c in data)
for (c of data)
for...in iterates keys.
JavaScript
name: world age: 76
name: world age: 76
Correct.
YAML
if (result = 33) {{}}
if (result == 33) {{}}
Use ==.
Java
int[] data = new int[34]; data[34] = 5;
int[] data = new int[34]; if (34 < data.length) data[34] = 5;
Check bounds.
Java
val data: Int = 'data'
val data: String = 'data'
Fix type.
Kotlin
x := 47
x := 47
Correct.
Go
class = 'world'
class_name = 'world'
'class' is a keyword.
Python
let count: number | null = null; count.toFixed(71);
let count: number | null = null; if(count!==null) count.toFixed(71);
Null check.
TypeScript
print 'result'
print('result')
print needs parentheses.
Python
if (index) console.log('yes') else console.log('no')
if (index) console.log('yes'); else console.log('no');
Missing semicolon.
JavaScript
fn process() -> i32 {{ 7 }}
fn process() -> i32 {{ 7 }}
Correct.
Rust
$values[10] = 5;
if (isset($values[10])) $values[10] = 5;
Check existence.
PHP
{{'name':4, 'status' 16}}
{{'name':4, 'status':16}}
Colon missing.
Python
List<int> list = [1,2,3];
List<int> list = [1,2,3];
Correct.
Dart
function handle() {{ return {{key:'info'}} }}
function handle() {{ return {{key:'info'}}; }}
Return object on same line.
JavaScript
if index = 21 then print('value') end
if index == 21 then print('value') end
Use ==.
Lua
arr[32]
if (length(arr) >= 32) arr[32]
Check length.
R
c == '50'
c === 50
Use strict equality.
JavaScript
<p>hello <b>data</p></b>
<p>hello <b>data</b></p>
Nest properly.
HTML
age: message age: data,
age: message age: data
Remove comma.
YAML
if z > 41 puts 'data'
if z > 41 puts 'data' end
Add 'end'.
Ruby
<?php // code ?>
<?php // code ?>
Correct.
PHP
System.out.println('test')
System.out.println('test');
Add semicolon.
Java
x <- 5; if (x > 3) print('large')
x <- 5; if (x > 3) print('large')
Correct.
R
let c: i32 = "data";
let c: &str = "data";
Type mismatch.
Rust
function baz(index) print(index) end
function baz(index) print(index) end
Correct.
Lua
[x*x for x in data if x > 61]
[x*x for x in data if x > 61]
Correct list comprehension.
Python
void main() {{ print('test') }}
void main() {{ print('test'); }}
Add semicolon.
Dart
$x = 5; if ($x -eq 5) { Write-Host 'yes' }
$x = 5; if ($x -eq 5) { Write-Host 'yes' }
Correct.
PowerShell
61item = 10
item61 = 10
Variable cannot start with digit.
Python
if ($num = 49) {{}}
if ($num -eq 49) {{}}
Use -eq.
PowerShell
let temp = 49; temp += 1;
let mut temp = 49; temp += 1;
Need mut to modify.
Rust
if (z = 5)
if (z == 5)
Use ==.
Scala
int items[46]; items[46]=5;
int items[46]; if(46<46){{}} else items[46]=5;
Bounds check.
C++