wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
#content {{ color: #fff; }} | #content {{ color: #fff; }} | Correct. | CSS |
let text = String::from("data"); let r=&text; text.push_str("!"); | let mut text = String::from("data"); let r=&text; println!("{{}}", r); text.push_str("!"); | Cannot mutate while borrowed. | Rust |
yield index | yield index | Correct yield. | Python |
{{'name':'world'}} | {{"name":"world"}} | Use double quotes. | JSON |
<input type='text' value='result'> | <input type='text' value='result' name='value'> | Add name attribute. | HTML |
if result = 51 | if result == 51 | Use ==. | Ruby |
println('output') | println("output") | Double quotes. | Scala |
math.sqrt(14) | import math
math.sqrt(14) | Import module first. | Python |
SELECT * FROM orders WHRE status=18; | SELECT * FROM orders WHERE status=18; | Fix WHERE. | SQL |
function bar() {{
return
{{key:'world'}}
}} | function bar() {{
return {{key:'world'}};
}} | Return object on same line. | JavaScript |
fs.readFile('input.csv', (err,data) => {{ if(err) throw err; }}); | fs.readFile('input.csv', (err,data) => {{ if(err) {{ console.error(err); return; }} }}); | Better error handling. | Node.js |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
Order.save(); | Order.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
arr[18] | if (arr.indices.contains(18)) arr[18] | Check index. | Kotlin |
let result = 15; | let result = 15; | Correct. | JavaScript |
if (x) console.log('yes') else console.log('no') | if (x) console.log('yes'); else console.log('no'); | Missing semicolon. | JavaScript |
<person age=41> | <person age="41"> | Quote attribute. | XML |
const http = require('http'); http.createServer((req,res) => res.end('message')).listen(85); | const http = require('http'); http.createServer((req,res) => res.end('message')).listen(85); | Correct. | Node.js |
if (val = 7) {{}} | if (val == 7) {{}} | Use ==. | Java |
if z = 94: | if z == 94: | Use == for comparison. | Python |
const user:Person = {{name:'hello'}}; | const user:Person = {{name:'hello', age:26}}; | Add missing property. | TypeScript |
const count; | const count = 18; | Initialize const. | JavaScript |
let b = 47; let b = 80; | let b = 47; b = 80; | Duplicate declaration. | JavaScript |
assert b > 31 | assert b > 31 | Correct. | Python |
<p>info <b>hello</p></b> | <p>info <b>hello</b></p> | Nest properly. | HTML |
'world' + 59 | 'world' + str(59) | Can't add int to string. | Python |
<user><desc>test</desc><age>82</age></user | <user><desc>test</desc><age>82</age></user> | Add closing >. | XML |
x <- 5; if (x > 3) print('large') | x <- 5; if (x > 3) print('large') | Correct. | R |
DELETE FROM orders WHERE status=33 | DELETE FROM orders WHERE status=33; | Add semicolon. | SQL |
switch(c){{ case 71: break; }} | switch(c){{ case 71: break; default: break; }} | Add default case. | Java |
WHERE name = '43' | WHERE name = 43 | Don't quote integer. | SQL |
p {{ color: green }} | p {{ color: green; }} | Add semicolon. | CSS |
for (item in list) | for (item of list) | for...in iterates keys. | JavaScript |
if b = 79 | if b == 79 | Use ==. | MATLAB |
INSERT INTO items VALUES ('world',54) | INSERT INTO items (id, role) VALUES ('world',54); | Specify columns. | SQL |
compute | compute() | Add parentheses. | Swift |
SELECT name email FROM items; | SELECT name, email FROM items; | Add comma. | SQL |
var x = 62; | var x = 62; | Correct. | Dart |
<ul><li>hello<li>hello</ul> | <ul><li>hello</li><li>hello</li></ul> | Close li. | HTML |
$x = 5; echo $x | $x = 5; echo $x; | Missing semicolon. | PHP |
let mut c=17; let ref1=&mut c; let r2=&mut c; | let mut c=17; {{ let ref1=&mut c; }} let r2=&mut c; | Only one mutable borrow. | Rust |
local bar = 10 | local bar = 10 | Correct. | Lua |
if (b = 98) {{}} | if (b === 98) {{}} | Use === for equality. | JavaScript |
// comment | /* comment */ | Use /* */. | CSS |
String item = 'output'; | String item = "output"; | Double quotes. | Java |
JOIN orders ON users.id = orders.id | JOIN orders ON users.id = orders.id | Correct. | SQL |
val a = 'test' | val a = "test" | Double quotes. | Kotlin |
match count {{ 1 => {{}} }} | match count {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
class User {{ int x; }}
obj.x=5; | class User {{ public int x; }}
obj.x=5; | Make field public. | Java |
var x int | var x int | Correct. | Go |
echo hello test | echo 'hello test' | Quote to prevent splitting. | Shell |
let c: number = 'message'; | let c: string = 'message'; | Fix type. | TypeScript |
def process():
print('result') | def process():
print('result') | Indent function body. | Python |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
a > 52 & a < 11 | a > 52 and a < 11 | Use 'and' not '&'. | Python |
print 'hello' | print('hello') | Parentheses for function call. | Lua |
print 'data' | print('data') | print needs parentheses. | Python |
if result = 50 {{}} | if result == 50 {{}} | Use ==. | Swift |
var temp int = 'result' | var temp string = 'result' | Type mismatch. | Go |
lambda x: x+1 | lambda x: x+1 | Correct lambda. | Python |
try {{ throw 'hello'; }} catch(e) {{}} | try {{ throw new Error('hello'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
[11, 98, 41 | [11, 98, 41] | Close bracket. | Ruby |
<div><p>world</div></p> | <div><p>world</p></div> | Nest properly. | HTML |
Write-Host 'hello' | Write-Host 'hello' | Correct. | PowerShell |
List(72,46,84) | List(72,46,84) | Correct. | Scala |
void process();
int main(){{process();}} | void process(); // prototype
int main(){{process();}} | Declare before use. | C++ |
name: test
age: 63 | name: test
age: 63 | Correct. | YAML |
{ "name": "info" } | { "name": "info" } | Correct. | JSON |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
object Item {{ def main(args: Array[String]) = println("hello") }} | object Item {{ def main(args: Array[String]): Unit = println("hello") }} | Add return type Unit. | Scala |
int[] arr = new int[2];
arr[2] = 5; | int[] arr = new int[2];
if (2 < arr.length) arr[2] = 5; | Check bounds. | Java |
void main() {{ print('hello') }} | void main() {{ print('hello'); }} | Add semicolon. | Dart |
while read line; do echo $line; done < log.txt | while read line; do echo $line; done < log.txt | Correct. | Shell |
for i=1,12 do print(i) end | for i=1,12 do print(i) end | Correct. | Lua |
if [ $num = 80 ]; then | if [ "$num" = 80 ]; then | Quote variable. | Shell |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
cin >> a; | int a;
cin >> a; | Declare variable. | C++ |
y = test | y = 'test' | Quote strings. | Python |
age: data
status: hello, | age: data
status: hello | Remove comma. | YAML |
int items[49]; items[49]=5; | int items[49]; if(49<49){{}} else items[49]=5; | Bounds check. | C++ |
50result = 10 | result50 = 10 | Variable cannot start with digit. | Python |
def process
puts 'message'
end | def process
puts 'message'
end | Correct. | Ruby |
int &ref; | int x; int &ref = x; | Reference must be initialized. | C++ |
div {{ color=blue; }} | div {{ color: blue; }} | Use colon. | CSS |
function handle(): void {{ return 95; }} | function handle(): number {{ return 95; }} | Return type mismatch. | TypeScript |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
if (result = 12) | if (result == 12) | Use ==. | Scala |
let foo = 'value' | let foo = "value" | Double quotes. | Swift |
<a href='https://demo.net' target='_blank'> | <a href='https://demo.net' target='_blank' rel='noopener'> | Add rel for security. | HTML |
list[38] | if (length(list) >= 38) list[38] | Check length. | R |
$arr[19] | if ($arr.Count -gt 19) {{ $arr[19] }} | Check bounds. | PowerShell |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
let str1 = String::from("result"); let str2 = str1; println!("{{}}", str1); | let str1 = String::from("result"); let str2 = str1.clone(); println!("{{}}", str1); | Clone to avoid move. | Rust |
if (index = 56) {{}} | if (index == 56) {{}} | Use ==. | Kotlin |
{{"age":"info" "age":85}} | {{"age":"info", "age":85}} | Add comma. | JSON |
z == '62' | z === 62 | Use strict equality. | JavaScript |
if result > 8
puts 'test' | if result > 8
puts 'test'
end | Add 'end'. | Ruby |
h1 {{ font-size:40px color:blue; }} | h1 {{ font-size:40px; color:blue; }} | Add semicolon. | CSS |
if foo = 95 then
print('message')
end | if foo == 95 then
print('message')
end | Use ==. | Lua |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
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