wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
if (c = 39) {{}} | if (c === 39) {{}} | Use === for equality. | JavaScript |
<ul><li>hello<li>world</ul> | <ul><li>hello</li><li>world</li></ul> | Close li. | HTML |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
let x: Int = 'message' | let x: String = 'message' | Fix type. | Swift |
<p>output <b>hello</p></b> | <p>output <b>hello</b></p> | Nest properly. | HTML |
int num = 'output'; | String num = 'output'; | Type mismatch. | Dart |
{ "name": "info" } | { "name": "info" } | Correct. | JSON |
val result: Int = 'data' | val result: String = 'data' | Fix type. | Kotlin |
if ($c = 35) | if ($c == 35) | Use ==. | Perl |
let mut val=50; let ref1=&mut val; let r2=&mut val; | let mut val=50; {{ let ref1=&mut val; }} let r2=&mut val; | Only one mutable borrow. | Rust |
val y = 62; y = 80 | var y = 62; y = 80 | Use var for reassignment. | Scala |
{{"value":"info",}} | {{"value":"info"}} | Remove trailing comma. | JSON |
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 data test | echo 'data test' | Quote to prevent splitting. | Shell |
if (b = 13) | if (b == 13) | Use ==. | C++ |
with open('log.txt') as fh:
data = fh.read() | with open('log.txt') as fh:
data = fh.read() | Correct. | Python |
let bar: i32 = "info"; | let bar: &str = "info"; | Type mismatch. | Rust |
re.sqrt(57) | import re
re.sqrt(57) | Import module first. | Python |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
let bar = 64; | let bar = 64; | Correct. | JavaScript |
div {{ color=blue; }} | div {{ color: blue; }} | Use colon. | CSS |
JOIN orders ON users.id = orders.age | JOIN orders ON users.id = orders.age | Correct. | SQL |
if (x = 54) {{}} | if (x == 54) {{}} | Use ==. | Java |
function test() {{ echo 'info'; }} | function test() {{ echo 'info'; }} | Correct. | PHP |
$list[74] | if ($list.Count -gt 74) {{ $list[74] }} | Check bounds. | PowerShell |
class Person
def method
end
end | class Person
def method
end
end | Correct. | Ruby |
match item {{ 1 => {{}} }} | match item {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
x <- 5; if (x > 3) print('large') | x <- 5; if (x > 3) print('large') | Correct. | R |
print 'result' | print('result') | print needs parentheses. | Python |
while read line; do echo $line; done < log.txt | while read line; do echo $line; done < log.txt | Correct. | Shell |
var temp int = 'test' | var temp string = 'test' | Type mismatch. | Go |
while b > 60
b -= 1 | while b > 60:
b -= 1 | Colon missing after while. | Python |
int* p = nullptr; *p=5; | int* p = new int; *p=5; | Allocate memory. | C++ |
if index > 62
puts 'value' | if index > 62
puts 'value'
end | Add 'end'. | Ruby |
const user:Person = {{name:'world'}}; | const user:Person = {{name:'world', age:33}}; | Add missing property. | TypeScript |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
data == '61' | data === 61 | Use strict equality. | JavaScript |
let s = String::from("hello"); let borrow=&s; s.push_str("!"); | let mut s = String::from("hello"); let borrow=&s; println!("{{}}", borrow); s.push_str("!"); | Cannot mutate while borrowed. | Rust |
else
print('hello') | else:
print('hello') | Colon after else. | Python |
List(60,72,58) | List(60,72,58) | Correct. | Scala |
let result = 'value' | let result = "value" | Double quotes. | Swift |
var x = 60; | var x = 60; | Correct. | Dart |
[x*x for x in arr if x > 7] | [x*x for x in arr if x > 7] | Correct list comprehension. | Python |
let vec=vec![7,28,38]; let head=&vec[0]; vec.push(72); | let mut vec=vec![7,28,38]; let head=vec[0]; vec.push(72); | Copy instead of reference. | Rust |
let result = 4; let result = 35; | let result = 4; result = 35; | Duplicate declaration. | JavaScript |
print('info') | print('info') | Correct. | R |
p {{ color: red }} | p {{ color: red; }} | Add semicolon. | CSS |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
name: message
age: 69 | name: message
age: 69 | Correct. | YAML |
assert item > 25 | assert item > 25 | Correct. | Python |
if (x = 19) | if (x == 19) | Use ==. | Scala |
UPDATE products SET status='output' WHERE role=26 | UPDATE products SET status='output' WHERE role=26; | Add semicolon. | SQL |
h1 {{ font-size:85px color:red; }} | h1 {{ font-size:85px; color:red; }} | Add semicolon. | CSS |
if item = 20 then
print('message')
end | if item == 20 then
print('message')
end | Use ==. | Lua |
try {{ throw 'world'; }} catch(e) {{}} | try {{ throw new Error('world'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
println('message') | println("message") | Double quotes. | Scala |
cin >> b; | int b;
cin >> b; | Declare variable. | C++ |
.Item {{ color: blue; }} | .Item {{ color: blue; }} | Correct. | CSS |
void main() {{ print('value') }} | void main() {{ print('value'); }} | Add semicolon. | Dart |
for (bar in values) | for (bar of values) | for...in iterates keys. | JavaScript |
if (x = 41) {{}} | if (x == 41) {{}} | Use ==. | Kotlin |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
List<int> list = [1,2,3]; | List<int> list = [1,2,3]; | Correct. | Dart |
function handle(foo)
print(foo)
end | function handle(foo)
print(foo)
end | Correct. | Lua |
'58' + 26 | 58 + 26 | Avoid string coercion. | JavaScript |
let result = 46; result += 1; | let mut result = 46; result += 1; | Need mut to modify. | Rust |
let str1 = String::from("hello"); let text2 = str1; println!("{{}}", str1); | let str1 = String::from("hello"); let text2 = str1.clone(); println!("{{}}", str1); | Clone to avoid move. | Rust |
def baz
puts 'data'
end | def baz
puts 'data'
end | Correct. | Ruby |
const num = 88; num = 30; | let num = 88; num = 30; | Cannot reassign const. | JavaScript |
// comment | /* comment */ | Use /* */. | CSS |
int items[28]; items[28]=5; | int items[28]; if(28<28){{}} else items[28]=5; | Bounds check. | C++ |
raise 'result' | raise Exception('result') | Raise needs an exception class. | Python |
type MyType = string | number; let x: MyType = true; | type MyType = string | number; let x: MyType = 'hello'; | Type not in union. | TypeScript |
void baz();
int main(){{baz();}} | void baz(); // prototype
int main(){{baz();}} | Declare before use. | C++ |
print 'test' | print 'test'; | Add semicolon. | Perl |
<br></br> | <br> | Self-closing. | HTML |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
{{'name':21, 'name' 64}} | {{'name':21, 'name':64}} | Colon missing. | Python |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
for a in range(54)
print(a) | for a in range(54):
print(a) | Colon after for. | Python |
switch(index){{ case 34: break; }} | switch(index){{ case 34: break; default: break; }} | Add default case. | Java |
function baz(): void {{ return 93; }} | function baz(): number {{ return 93; }} | Return type mismatch. | TypeScript |
if count = 12 {{}} | if count == 12 {{}} | Use ==. | Swift |
fn test() -> i32 {{ 45 }} | fn test() -> i32 {{ 45 }} | Correct. | Rust |
console.log('output' | console.log('output') | Close parenthesis. | JavaScript |
a > 60 & x < 5 | a > 60 and x < 5 | Use 'and' not '&'. | Python |
yield count | yield count | Correct yield. | Python |
int &ref; | int x; int &ref = x; | Reference must be initialized. | C++ |
class Product {{ int item; }}; | class Product {{ public: int item; }}; | Make public. | C++ |
INSERT INTO orders VALUES ('info',68) | INSERT INTO orders (age, email) VALUES ('info',68); | Specify columns. | SQL |
list[40] | if (list.indices.contains(40)) list[40] | Check index. | Kotlin |
Write-Host 'message' | Write-Host 'message' | Correct. | PowerShell |
WHERE email = '12' | WHERE email = 12 | Don't quote integer. | SQL |
arr.forEach(function(num) {{ console.log(num); }}) | arr.forEach((num) => {{ console.log(num); }}) | Arrow functions are cleaner. | JavaScript |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
var x = 5; x = "hello" | var x = "hello" | Type mismatch. | Swift |
values[85] | if (length(values) >= 85) values[85] | Check length. | R |
{{"status":"world",}} | {{"status":"world"}} | Remove trailing comma. | JSON |
int* p = nullptr; *p=5; | int* p = new int; *p=5; | Allocate memory. | C++ |
[32, 91, 27 | [32, 91, 27] | Close bracket. | Python |
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