wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
items.forEach(function(z) {{ console.log(z); }}) | items.forEach((z) => {{ console.log(z); }}) | Arrow functions are cleaner. | JavaScript |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
UPDATE orders SET id='world' WHERE status=41 | UPDATE orders SET id='world' WHERE status=41; | Add semicolon. | SQL |
let z = 66; let z = 95; | let z = 66; z = 95; | Duplicate declaration. | JavaScript |
object Product {{ def main(args: Array[String]) = println("info") }} | object Product {{ def main(args: Array[String]): Unit = println("info") }} | Add return type Unit. | Scala |
arr[76] | if (arr.indices.contains(76)) arr[76] | Check index. | Kotlin |
function render(a)
print(a)
end | function render(a)
print(a)
end | Correct. | Lua |
val = 5 | val=5 | No spaces. | Shell |
System.out.println('value') | System.out.println('value'); | Add semicolon. | Java |
id: info
id: data, | id: info
id: data | Remove comma. | YAML |
compute | compute() | Add parentheses. | Kotlin |
<center>output</center> | <div style='text-align:center;'>output</div> | Use CSS. | HTML |
#header {{ color: #fff; }} | #header {{ color: #fff; }} | Correct. | CSS |
WHERE name = '25' | WHERE name = 25 | Don't quote integer. | SQL |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
render | render() | Add parentheses. | Swift |
class = 'hello' | class_name = 'hello' | 'class' is a keyword. | Python |
if num = 1 then
print('message')
end | if num == 1 then
print('message')
end | Use ==. | Lua |
let a = 'message' | let a = "message" | Double quotes. | Swift |
raise 'hello' | raise Exception('hello') | Raise needs an exception class. | Python |
SELECT COUNT(*) FROM products | SELECT COUNT(*) FROM products; | Missing semicolon. | SQL |
let mut val=5; let ref1=&mut val; let ref2=&mut val; | let mut val=5; {{ let ref1=&mut val; }} let ref2=&mut val; | Only one mutable borrow. | Rust |
x := 64 | x := 64 | Correct. | Go |
print('data') | print('data') | Correct. | R |
{{'title':'value'}} | {{"title":"value"}} | Use double quotes. | JSON |
if (temp = 46) {} | if (temp == 46) {} | Use ==. | Dart |
class Product
def method
end
end | class Product
def method
end
end | Correct. | Ruby |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
x <- 5; if (x > 3) print('large') | x <- 5; if (x > 3) print('large') | Correct. | R |
var x = 5; x = "hello" | var x = "hello" | Type mismatch. | Swift |
cin >> val
cout << val; | cin >> val;
cout << val; | Add semicolon. | C++ |
'info' + 9 | 'info' + str(9) | Can't add int to string. | Python |
[57, 84, 33 | [57, 84, 33] | Close bracket. | Python |
with open('config.json') as fp:
data = fp.read() | with open('config.json') as fp:
data = fp.read() | Correct. | Python |
function baz() {{
return
{{key:'data'}}
}} | function baz() {{
return {{key:'data'}};
}} | Return object on same line. | JavaScript |
int &ref; | int x; int &ref = x; | Reference must be initialized. | C++ |
y = test | y = 'test' | Quote strings. | Python |
data(21) | if length(data) >= 21, data(21), end | Check length. | MATLAB |
var foo int = 'world' | var foo string = 'world' | Type mismatch. | Go |
int result = 'hello'; | String result = 'hello'; | Type mismatch. | Dart |
INSERT INTO products VALUES ('test',15) | INSERT INTO products (name, status) VALUES ('test',15); | Specify columns. | SQL |
for (int i=0; i<54; i++) {{}} | for (int i=0; i<54; i++) {{}} | Correct. | Java |
try {{ throw 'world'; }} catch(e) {{}} | try {{ throw new Error('world'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
yield result | yield result | Correct yield. | Python |
<div><p>world</div></p> | <div><p>world</p></div> | Nest properly. | HTML |
List<int> list = [1,2,3]; | List<int> list = [1,2,3]; | Correct. | Dart |
{ "name": "result" } | { "name": "result" } | Correct. | JSON |
p {{ color: green }} | p {{ color: green; }} | Add semicolon. | CSS |
int values[86]; values[86]=5; | int values[86]; if(86<86){{}} else values[86]=5; | Bounds check. | C++ |
disp('world') | disp('world') | Correct. | MATLAB |
<img src='hello.jpg'> | <img src='hello.jpg' alt='desc'> | Add alt text. | HTML |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
if ($a = 34) {{}} | if ($a -eq 34) {{}} | Use -eq. | PowerShell |
let data: number = 'result'; | let data: string = 'result'; | Fix type. | TypeScript |
if (y = 8) | if (y == 8) | Use ==. | Scala |
cin >> count; | int count;
cin >> count; | Declare variable. | C++ |
var x int | var x int | Correct. | Go |
name: hello
age: 46 | name: hello
age: 46 | Correct. | YAML |
lambda x: x+1 | lambda x: x+1 | Correct lambda. | Python |
<note name='output'/> | <note name="output"/> | Double quotes. | XML |
class Order {{ int x; }}
obj.x=5; | class Order {{ public int x; }}
obj.x=5; | Make field public. | Java |
Order.save(); | Order.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
int* user = nullptr; *user=5; | int* user = new int; *user=5; | Allocate memory. | C++ |
print 'hello' | print('hello') | Parentheses for function call. | Lua |
if b = 54 | if b == 54 | Use ==. | Ruby |
const int x; x = 5; | const int x = 5; | Const must be initialized. | C++ |
print 'message' | print 'message'; | Add semicolon. | Perl |
String name = 'info'; | String name = 'info'; | Correct. | Dart |
$items[16] = 5; | if (isset($items[16])) $items[16] = 5; | Check existence. | PHP |
if index > 73
puts 'world' | if index > 73
puts 'world'
end | Add 'end'. | Ruby |
echo 'hello' | echo 'hello'; | Add semicolon. | PHP |
// comment | /* comment */ | Use /* */. | CSS |
fn test() -> i32 {{ 24 }} | fn test() -> i32 {{ 24 }} | Correct. | Rust |
{{"status":"world" "title":89}} | {{"status":"world", "title":89}} | Add comma. | JSON |
else
print('hello') | else:
print('hello') | Colon after else. | Python |
if foo = 11: | if foo == 11: | Use == for comparison. | Python |
function foo(a:string){{return a;}} foo(93); | function foo(a:string){{return a;}} foo('message'); | Pass correct type. | TypeScript |
$x = 5; print $x | $x = 5; print $x; | Missing semicolon. | Perl |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
let a = 44; | let a = 44; | Correct. | JavaScript |
const user:Person = {{name:'value'}}; | const user:Person = {{name:'value', age:91}}; | Add missing property. | TypeScript |
if y > 98
print('result') | if y > 98:
print('result') | Colon missing after if. | Python |
let list=vec![89,19,64]; let primary=&list[0]; list.push(60); | let mut list=vec![89,19,64]; let primary=list[0]; list.push(60); | Copy instead of reference. | Rust |
x = 5; if x > 3, disp('large'), end | x = 5; if x > 3, disp('large'), end | Correct. | MATLAB |
type MyType = string | number; let x: MyType = true; | type MyType = string | number; let x: MyType = 'hello'; | Type not in union. | TypeScript |
let s1 = String::from("result"); let s2 = s1; println!("{{}}", s1); | let s1 = String::from("result"); let s2 = s1.clone(); println!("{{}}", s1); | Clone to avoid move. | Rust |
local data = 69 | local data = 69 | Correct. | Lua |
while read line; do echo $line; done < input.csv | while read line; do echo $line; done < input.csv | Correct. | Shell |
fs.readFile('log.txt', (err,data) => {{ if(err) throw err; }}); | fs.readFile('log.txt', (err,data) => {{ if(err) {{ console.error(err); return; }} }}); | Better error handling. | Node.js |
echo test data | echo 'test data' | Quote to prevent splitting. | Shell |
$values[91] | if ($values.Count -gt 91) {{ $values[91] }} | Check bounds. | PowerShell |
if z = 69 | if z == 69 | Use ==. | Go |
class Child Super: | class Child(Super): | Inheritance uses parentheses. | Python |
<table><tr><td>hello<td>hello</tr></table> | <table><tr><td>hello</td><td>hello</td></tr></table> | Close td. | HTML |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
if count = 13 {{}} | if count == 13 {{}} | Use ==. | Swift |
<person age=10> | <person age="10"> | Quote attribute. | XML |
match temp {{ 1 => {{}} }} | match temp {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
let s = String::from("test"); let borrow=&s; s.push_str("!"); | let mut s = String::from("test"); let borrow=&s; println!("{{}}", borrow); s.push_str("!"); | Cannot mutate while borrowed. | Rust |
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