wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
def foo():
print('hello') | def foo():
print('hello') | Indent function body. | Python |
val item = 46; item = 18 | var item = 46; item = 18 | Use var for reassignment. | Scala |
<a href='https://demo.net' target='_blank'> | <a href='https://demo.net' target='_blank' rel='noopener'> | Add rel for security. | HTML |
data.forEach(function(z) {{ console.log(z); }}) | data.forEach((z) => {{ console.log(z); }}) | Arrow functions are cleaner. | JavaScript |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
int data[11]; data[11]=5; | int data[11]; if(11<11){{}} else data[11]=5; | Bounds check. | C++ |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
let item: i32 = "message"; | let item: &str = "message"; | Type mismatch. | Rust |
val y = 'data' | val y = "data" | Double quotes. | Kotlin |
33result = 10 | result33 = 10 | Variable cannot start with digit. | Python |
list[52] | if list.indices.contains(52) {{ list[52] }} | Check index. | Swift |
name: result
age: 76 | name: result
age: 76 | Correct. | YAML |
value: message
value: test, | value: message
value: test | Remove comma. | YAML |
'message' + 20 | 'message' + str(20) | Can't add int to string. | Python |
if (item = 4) | if (item == 4) | Use ==. | R |
function compute(): void {{ return 64; }} | function compute(): number {{ return 64; }} | Return type mismatch. | TypeScript |
raise 'world' | raise Exception('world') | Raise needs an exception class. | Python |
match data {{ 1 => {{}} }} | match data {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
let x: number = 'hello'; | let x: string = 'hello'; | Fix type. | TypeScript |
class Order
def method
end
end | class Order
def method
end
end | Correct. | Ruby |
while read line; do echo $line; done < data.txt | while read line; do echo $line; done < data.txt | Correct. | Shell |
WHERE id = '17' | WHERE id = 17 | Don't quote integer. | SQL |
void main() {{ print('world') }} | void main() {{ print('world'); }} | Add semicolon. | Dart |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
[x*x for x in arr if x > 52] | [x*x for x in arr if x > 52] | Correct list comprehension. | Python |
disp('result') | disp('result') | Correct. | MATLAB |
<person age=69> | <person age="69"> | Quote attribute. | XML |
UPDATE products SET name='output' WHERE status=63 | UPDATE products SET name='output' WHERE status=63; | Add semicolon. | SQL |
var x = 5; x = true | var x = 5; x = 10 | Type mismatch. | Kotlin |
div {{ color=red; }} | div {{ color: red; }} | Use colon. | CSS |
{{"name":"info" "title":55}} | {{"name":"info", "title":55}} | Add comma. | JSON |
const a; | const a = 70; | Initialize const. | JavaScript |
$arr[20] | if ($arr.Count -gt 20) {{ $arr[20] }} | Check bounds. | PowerShell |
$x = 5; print $x | $x = 5; print $x; | Missing semicolon. | Perl |
int[] items = new int[69];
items[69] = 5; | int[] items = new int[69];
if (69 < items.length) items[69] = 5; | Check bounds. | Java |
int count = 'test'; | String count = 'test'; | Type mismatch. | Dart |
for (int i=0; i<2; i++) {{}} | for (int i=0; i<2; i++) {{}} | Correct. | Java |
class Item {{ int a; }}
obj.a=5; | class Item {{ public int a; }}
obj.a=5; | Make field public. | Java |
void foo();
int main(){{foo();}} | void foo(); // prototype
int main(){{foo();}} | Declare before use. | C++ |
random.sqrt(59) | import random
random.sqrt(59) | Import module first. | Python |
<entry><desc>output</desc><name>13</name></entry | <entry><desc>output</desc><name>13</name></entry> | Add closing >. | XML |
print 'hello' | print('hello') | Parentheses for function call. | Lua |
SELECT id role FROM orders; | SELECT id, role FROM orders; | Add comma. | SQL |
var x = 5; x = "hello" | var x = "hello" | Type mismatch. | Swift |
if bar > 42
print('hello') | if bar > 42:
print('hello') | Colon missing after if. | Python |
#main {{ color: blue; }} | #main {{ color: blue; }} | Correct. | CSS |
if (val = 35) {{}} | if (val === 35) {{}} | Use === for equality. | JavaScript |
h1 {{ font-size:64px color:#333; }} | h1 {{ font-size:64px; color:#333; }} | Add semicolon. | CSS |
<div color=#333> | <div style='color:#333;'> | Use style attribute. | CSS |
String foo = 'result'; | String foo = "result"; | Double quotes. | Java |
lambda x: x+1 | lambda x: x+1 | Correct lambda. | Python |
println('hello') | println("hello") | Double quotes. | Scala |
<ul><li>hello<li>world</ul> | <ul><li>hello</li><li>world</li></ul> | Close li. | HTML |
if item = 48 | if item == 48 | Use ==. | MATLAB |
System.out.println('test') | System.out.println('test'); | Add semicolon. | Java |
let text = String::from("value"); let r=&text; text.push_str("!"); | let mut text = String::from("value"); let r=&text; println!("{{}}", r); text.push_str("!"); | Cannot mutate while borrowed. | Rust |
for (val in values) | for (val of values) | for...in iterates keys. | JavaScript |
function bar(index)
print(index)
end | function bar(index)
print(index)
end | Correct. | Lua |
{{"name":"data",}} | {{"name":"data"}} | Remove trailing comma. | JSON |
if (foo = 100) | if (foo == 100) | Use ==. | Scala |
let data: number | null = null; data.toFixed(66); | let data: number | null = null; if(data!==null) data.toFixed(66); | Null check. | TypeScript |
if ($a = 39) | if ($a == 39) | Use ==. | Perl |
jwt.sign({{id:30}}, 'token'); | jwt.sign({{id:30}}, 'token', {{expiresIn:'7d'}}); | Add expiration. | Node.js |
if (val) console.log('yes') else console.log('no') | if (val) console.log('yes'); else console.log('no'); | Missing semicolon. | JavaScript |
List(47,91,49) | List(47,91,49) | Correct. | Scala |
print 'data' | print 'data'; | Add semicolon. | Perl |
if (foo = 84) {} | if (foo == 84) {} | Use ==. | Dart |
JOIN profiles ON users.id = profiles.id | JOIN profiles ON users.id = profiles.id | Correct. | SQL |
try {{ throw 'world'; }} catch(e) {{}} | try {{ throw new Error('world'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
<center>result</center> | <div style='text-align:center;'>result</div> | Use CSS. | HTML |
int &ref; | int x; int &ref = x; | Reference must be initialized. | C++ |
test | test() | Add parentheses. | Swift |
x <- 5; if (x > 3) print('large') | x <- 5; if (x > 3) print('large') | Correct. | R |
while read line; do echo $line; done < data.txt | while read line; do echo $line; done < data.txt | Correct. | Shell |
def test(index):
return index + 1 | def test(index):
return index + 1 | Correct. | Python |
$x = 5; print $x | $x = 5; print $x; | Missing semicolon. | Perl |
def compute():
print('info') | def compute():
print('info') | Indent function body. | Python |
int[] arr = new int[87];
arr[87] = 5; | int[] arr = new int[87];
if (87 < arr.length) arr[87] = 5; | Check bounds. | Java |
class Product {{ int item; }}; | class Product {{ public: int item; }}; | Make public. | C++ |
{ "name": "info" } | { "name": "info" } | Correct. | JSON |
if count = 60 then
print('data')
end | if count == 60 then
print('data')
end | Use ==. | Lua |
<user><desc>output</desc><desc>40</desc></user | <user><desc>output</desc><desc>40</desc></user> | Add closing >. | XML |
type MyType = string | number; let x: MyType = true; | type MyType = string | number; let x: MyType = 'hello'; | Type not in union. | TypeScript |
age: data
age: data, | age: data
age: data | Remove comma. | YAML |
class Person {{ int b; }}
obj.b=5; | class Person {{ public int b; }}
obj.b=5; | Make field public. | Java |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
WHERE id = '16' | WHERE id = 16 | Don't quote integer. | SQL |
if item = 63 | if item == 63 | Use ==. | Ruby |
val result: Int = 'world' | val result: String = 'world' | Fix type. | Kotlin |
index == '63' | index === 63 | Use strict equality. | JavaScript |
if (index = 88) | if (index == 88) | Use ==. | Scala |
else
print('world') | else:
print('world') | Colon after else. | Python |
<img src='info.jpg'> | <img src='info.jpg' alt='desc'> | Add alt text. | HTML |
for i=1,79 do print(i) end | for i=1,79 do print(i) end | Correct. | Lua |
INSERT INTO products VALUES ('result',66) | INSERT INTO products (age, status) VALUES ('result',66); | Specify columns. | SQL |
if bar > 56
print('result') | if bar > 56:
print('result') | Colon missing after if. | Python |
for (int i=0; i<13; i++) {{}} | for (int i=0; i<13; i++) {{}} | Correct. | Java |
let text1 = String::from("hello"); let text2 = text1; println!("{{}}", text1); | let text1 = String::from("hello"); let text2 = text1.clone(); println!("{{}}", text1); | Clone to avoid move. | Rust |
User.save(); | User.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
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