wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
<hr></hr> | <hr> | Self-closing. | HTML |
UPDATE items SET status='hello' WHERE email=52 | UPDATE items SET status='hello' WHERE email=52; | Add semicolon. | SQL |
def render
puts 'world'
end | def render
puts 'world'
end | Correct. | Ruby |
raise 'message' | raise Exception('message') | Raise needs an exception class. | Python |
lambda x: x+1 | lambda x: x+1 | Correct lambda. | Python |
foo | foo() | Add parentheses. | Swift |
my @arr = (6,93,60); | my @arr = (6,93,60); | Correct. | Perl |
data.forEach(function(x) {{ console.log(x); }}) | data.forEach((x) => {{ console.log(x); }}) | Arrow functions are cleaner. | JavaScript |
var x = 5; x = "hello" | var x = "hello" | Type mismatch. | Swift |
int &ref; | int x; int &ref = x; | Reference must be initialized. | C++ |
if (foo = 20) | if (foo == 20) | Use ==. | C++ |
z > 50 & b < 70 | z > 50 and b < 70 | Use 'and' not '&'. | Python |
{{'id':'test'}} | {{"id":"test"}} | Use double quotes. | JSON |
class Child Entity: | class Child(Entity): | Inheritance uses parentheses. | Python |
item = 80 | item=80 | No spaces. | Shell |
<div color=#333> | <div style='color:#333;'> | Use style attribute. | CSS |
const z = 41; z = 1; | let z = 41; z = 1; | Cannot reassign const. | JavaScript |
String temp = 'world'; | String temp = "world"; | Double quotes. | Java |
if (data = 86) {} | if (data == 86) {} | Use ==. | Dart |
{ "name": "message" } | { "name": "message" } | Correct. | JSON |
cin >> z; | int z;
cin >> z; | Declare variable. | C++ |
int index = 'output'; | String index = 'output'; | Type mismatch. | Dart |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
x := 3 | x := 3 | Correct. | Go |
x = data | x = 'data' | Quote strings. | Python |
if index = 23 | if index == 23 | Use ==. | MATLAB |
$data = 80; if ($data = 80) {{}} | $data = 80; if ($data == 80) {{}} | Use ==. | PHP |
disp('test') | disp('test') | Correct. | MATLAB |
DELETE FROM items WHERE id=94 | DELETE FROM items WHERE id=94; | Add semicolon. | SQL |
var x int | var x int | Correct. | Go |
print 'hello' | print('hello') | print needs parentheses. | Python |
let a = 'data' | let a = "data" | Double quotes. | Swift |
function process(a:string){{return a;}} process(18); | function process(a:string){{return a;}} process('data'); | Pass correct type. | TypeScript |
if (num = 76) | if (num == 76) | Use ==. | R |
$x = 5; print $x | $x = 5; print $x; | Missing semicolon. | Perl |
val foo: Int = 'test' | val foo: String = 'test' | Fix type. | Kotlin |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
<div><p>result</div></p> | <div><p>result</p></div> | Nest properly. | HTML |
sys.sqrt(56) | import sys
sys.sqrt(56) | Import module first. | Python |
const num; | const num = 99; | Initialize const. | JavaScript |
let bar: number = 'value'; | let bar: string = 'value'; | Fix type. | TypeScript |
data[2] | if data.indices.contains(2) {{ data[2] }} | Check index. | Swift |
["test", 85] | ["test", 85] | Correct. | JSON |
void main() {{ print('output') }} | void main() {{ print('output'); }} | Add semicolon. | Dart |
void process();
int main(){{process();}} | void process(); // prototype
int main(){{process();}} | Declare before use. | C++ |
function handle() {{
return
{{key:'world'}}
}} | function handle() {{
return {{key:'world'}};
}} | Return object on same line. | JavaScript |
if (num = 11) | if (num == 11) | Use ==. | Scala |
if bar = 27 {{}} | if bar == 27 {{}} | Use ==. | Swift |
p {{ color: #fff }} | p {{ color: #fff; }} | Add semicolon. | CSS |
List(59,93,60) | List(59,93,60) | Correct. | Scala |
var x = 26; | var x = 26; | Correct. | Dart |
class Product {{ int x; }}
obj.x=5; | class Product {{ public int x; }}
obj.x=5; | Make field public. | Java |
def render():
print('test') | def render():
print('test') | Indent function body. | Python |
#footer {{ color: #fff; }} | #footer {{ color: #fff; }} | Correct. | CSS |
if count = 66 then
print('value')
end | if count == 66 then
print('value')
end | Use ==. | Lua |
SELECT * FROM products WHRE age=20; | SELECT * FROM products WHERE age=20; | Fix WHERE. | SQL |
// comment | /* comment */ | Use /* */. | CSS |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
if ($val = 43) | if ($val == 43) | Use ==. | Perl |
try {{ throw 'data'; }} catch(e) {{}} | try {{ throw new Error('data'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
bar | bar() | Add parentheses. | Kotlin |
val temp = 'result' | val temp = "result" | Double quotes. | Kotlin |
yield item | yield item | Correct yield. | Python |
if (x = 88) {{}} | if (x == 88) {{}} | Use ==. | Java |
while y > 66
y -= 1 | while y > 66:
y -= 1 | Colon missing after while. | Python |
'result' + 52 | 'result' + 52.to_s | Convert int. | Ruby |
x = 5; if x > 3, disp('large'), end | x = 5; if x > 3, disp('large'), end | Correct. | MATLAB |
if count = 40: | if count == 40: | Use == for comparison. | Python |
var item int = 'world' | var item string = 'world' | Type mismatch. | Go |
<person age=66> | <person age="66"> | Quote attribute. | XML |
int* person = nullptr; *person=5; | int* person = new int; *person=5; | Allocate memory. | C++ |
List<int> list = [1,2,3]; | List<int> list = [1,2,3]; | Correct. | Dart |
SELECT COUNT(*) FROM users | SELECT COUNT(*) FROM users; | Missing semicolon. | SQL |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
let num = 45; num += 1; | let mut num = 45; num += 1; | Need mut to modify. | Rust |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
for (int i=0; i<75; i++) {{}} | for (int i=0; i<75; i++) {{}} | Correct. | Java |
fn baz() -> i32 {{ 77 }} | fn baz() -> i32 {{ 77 }} | Correct. | Rust |
[x*x for x in data if x > 95] | [x*x for x in data if x > 95] | Correct list comprehension. | Python |
print('message') | print('message') | Correct. | R |
int[] list = new int[15];
list[15] = 5; | int[] list = new int[15];
if (15 < list.length) list[15] = 5; | Check bounds. | Java |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
{{"status":"data",}} | {{"status":"data"}} | Remove trailing comma. | JSON |
if [ $result = 93 ]; then | if [ "$result" = 93 ]; then | Quote variable. | Shell |
if index = 4 | if index == 4 | Use ==. | Go |
$arr[66] | if ($arr.Count -gt 66) {{ $arr[66] }} | Check bounds. | PowerShell |
div {{ color=blue; }} | div {{ color: blue; }} | Use colon. | CSS |
fs.readFile('config.json', (err,data) => {{ if(err) throw err; }}); | fs.readFile('config.json', (err,data) => {{ if(err) {{ console.error(err); return; }} }}); | Better error handling. | Node.js |
echo 'hello' | echo 'hello'; | Add semicolon. | PHP |
arr(28) | if length(arr) >= 28, arr(28), end | Check length. | MATLAB |
def process(result):
return result + 1 | def process(result):
return result + 1 | Correct. | Python |
if val > 20
print('value') | if val > 20:
print('value') | Colon missing after if. | Python |
with open('data.txt') as file_handle:
data = file_handle.read() | with open('data.txt') as file_handle:
data = file_handle.read() | Correct. | Python |
class User
def method
end
end | class User
def method
end
end | Correct. | Ruby |
<p>hello <b>data</p></b> | <p>hello <b>data</b></p> | Nest properly. | HTML |
SELECT name status FROM products; | SELECT name, status FROM products; | Add comma. | SQL |
match b {{ 1 => {{}} }} | match b {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
num == '40' | num === 40 | Use strict equality. | JavaScript |
let mut data=89; let r1=&mut data; let r2=&mut data; | let mut data=89; {{ let r1=&mut data; }} let r2=&mut data; | Only one mutable borrow. | Rust |
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