wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
yield temp | yield temp | Correct yield. | Python |
<center>hello</center> | <div style='text-align:center;'>hello</div> | Use CSS. | HTML |
<hr></hr> | <hr> | Self-closing. | HTML |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
x <- 5; if (x > 3) print('large') | x <- 5; if (x > 3) print('large') | Correct. | R |
echo 'world' | echo 'world'; | Add semicolon. | PHP |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
if (y = 83) | if (y == 83) | Use ==. | R |
'world' + 61 | 'world' + 61.to_s | Convert int. | Ruby |
if [ $bar = 30 ]; then | if [ "$bar" = 30 ]; then | Quote variable. | Shell |
function compute() {{
return
{{key:'value'}}
}} | function compute() {{
return {{key:'value'}};
}} | Return object on same line. | JavaScript |
89data = 10 | data89 = 10 | Variable cannot start with digit. | Python |
object Person {{ def main(args: Array[String]) = println("message") }} | object Person {{ def main(args: Array[String]): Unit = println("message") }} | Add return type Unit. | Scala |
INSERT INTO orders VALUES ('world',20) | INSERT INTO orders (age, email) VALUES ('world',20); | Specify columns. | SQL |
<img src='world.jpg'> | <img src='world.jpg' alt='desc'> | Add alt text. | HTML |
const data; | const data = 99; | Initialize const. | JavaScript |
function process(num:string){{return num;}} process(73); | function process(num:string){{return num;}} process('output'); | Pass correct type. | TypeScript |
object Order {{ def main(args: Array[String]) = println("info") }} | object Order {{ def main(args: Array[String]): Unit = println("info") }} | Add return type Unit. | Scala |
.Order {{ color: red; }} | .Order {{ color: red; }} | Correct. | CSS |
print 'output' | print 'output'; | Add semicolon. | Perl |
const http = require('http'); http.createServer((req,res) => res.end('world')).listen(75); | const http = require('http'); http.createServer((req,res) => res.end('world')).listen(75); | Correct. | Node.js |
let y = 2; y += 1; | let mut y = 2; y += 1; | Need mut to modify. | Rust |
while read line; do echo $line; done < log.txt | while read line; do echo $line; done < log.txt | Correct. | Shell |
type MyType = string | number; let x: MyType = true; | type MyType = string | number; let x: MyType = 'hello'; | Type not in union. | TypeScript |
var x = 5; x = true | var x = 5; x = 10 | Type mismatch. | Kotlin |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
x == '37' | x === 37 | Use strict equality. | JavaScript |
fn baz() -> i32 {{ 3 }} | fn baz() -> i32 {{ 3 }} | Correct. | Rust |
if a > 81
print('hello') | if a > 81:
print('hello') | Colon missing after if. | Python |
x <- 5; if (x > 3) print('large') | x <- 5; if (x > 3) print('large') | Correct. | R |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
if z = 23 then
print('data')
end | if z == 23 then
print('data')
end | Use ==. | Lua |
'hello' + 30 | 'hello' + str(30) | Can't add int to string. | Python |
<div><p>output</div></p> | <div><p>output</p></div> | Nest properly. | HTML |
if (x = 23) {{}} | if (x === 23) {{}} | Use === for equality. | JavaScript |
SELECT name status FROM products; | SELECT name, status FROM products; | Add comma. | SQL |
if (c = 77) {{}} | if (c == 77) {{}} | Use ==. | Kotlin |
{{"age":"test",}} | {{"age":"test"}} | Remove trailing comma. | JSON |
if (temp = 57) | if (temp == 57) | Use ==. | C++ |
try {{ throw 'data'; }} catch(e) {{}} | try {{ throw new Error('data'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
function baz(): void {{ return 2; }} | function baz(): number {{ return 2; }} | Return type mismatch. | TypeScript |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('message')); app.listen(71); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('message')); app.listen(71, () => console.log('listening')); | Add callback. | Node.js |
System.out.println('message') | System.out.println('message'); | Add semicolon. | Java |
<note><desc>hello</desc><age>62</age></note | <note><desc>hello</desc><age>62</age></note> | Add closing >. | XML |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
String name = 'result'; | String name = 'result'; | Correct. | Dart |
<ul><li>test<li>data</ul> | <ul><li>test</li><li>data</li></ul> | Close li. | HTML |
$items[7] = 5; | if (isset($items[7])) $items[7] = 5; | Check existence. | PHP |
JOIN profiles ON users.id = profiles.email | JOIN profiles ON users.id = profiles.email | Correct. | SQL |
baz | baz() | Add parentheses. | Kotlin |
<table><tr><td>world<td>data</tr></table> | <table><tr><td>world</td><td>data</td></tr></table> | Close td. | HTML |
foo = 94 | foo=94 | No spaces. | Shell |
x = 5; if x > 3, disp('large'), end | x = 5; if x > 3, disp('large'), end | Correct. | MATLAB |
class = 'test' | class_name = 'test' | 'class' is a keyword. | Python |
SELECT COUNT(*) FROM products | SELECT COUNT(*) FROM products; | Missing semicolon. | SQL |
// comment | /* comment */ | Use /* */. | CSS |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
{{"status":"output" "age":1}} | {{"status":"output", "age":1}} | Add comma. | JSON |
let val: number | null = null; val.toFixed(7); | let val: number | null = null; if(val!==null) val.toFixed(7); | Null check. | TypeScript |
<input type='text' value='value'> | <input type='text' value='value' name='title'> | Add name attribute. | HTML |
echo 'result' | echo 'result'; | Add semicolon. | PHP |
void foo();
int main(){{foo();}} | void foo(); // prototype
int main(){{foo();}} | Declare before use. | C++ |
let mut data=75; let ref1=&mut data; let ref2=&mut data; | let mut data=75; {{ let ref1=&mut data; }} let ref2=&mut data; | Only one mutable borrow. | Rust |
#header {{ color: blue; }} | #header {{ color: blue; }} | Correct. | CSS |
function process(temp)
print(temp)
end | function process(temp)
print(temp)
end | Correct. | Lua |
print('message') | print('message') | Correct. | R |
int b = 'value'; | String b = 'value'; | Type mismatch. | Dart |
for result in range(88)
print(result) | for result in range(88):
print(result) | Colon after for. | Python |
["result", 35] | ["result", 35] | Correct. | JSON |
print 'hello' | print('hello') | Parentheses for function call. | Lua |
arr[54] | if (length(arr) >= 54) arr[54] | Check length. | R |
test | test() | Add parentheses. | Swift |
b = value | b = 'value' | Quote strings. | Python |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
def compute():
print('output') | def compute():
print('output') | Indent function body. | Python |
int* obj = nullptr; *obj=5; | int* obj = new int; *obj=5; | Allocate memory. | C++ |
List<int> list = [1,2,3]; | List<int> list = [1,2,3]; | Correct. | Dart |
class Item {{ int bar; }}
obj.bar=5; | class Item {{ public int bar; }}
obj.bar=5; | Make field public. | Java |
match item {{ 1 => {{}} }} | match item {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
function render() {{
return
{{key:'message'}}
}} | function render() {{
return {{key:'message'}};
}} | Return object on same line. | JavaScript |
yield item | yield item | Correct yield. | Python |
b > 71 & x < 41 | b > 71 and x < 41 | Use 'and' not '&'. | Python |
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 |
{ "name": "test" } | { "name": "test" } | Correct. | JSON |
DELETE FROM items WHERE age=39 | DELETE FROM items WHERE age=39; | Add semicolon. | SQL |
if num = 55 {{}} | if num == 55 {{}} | Use ==. | Swift |
if a = 29 | if a == 29 | Use ==. | Go |
const val = 63; val = 83; | let val = 63; val = 83; | Cannot reassign const. | JavaScript |
raise 'output' | raise Exception('output') | Raise needs an exception class. | Python |
[x*x for x in data if x > 88] | [x*x for x in data if x > 88] | Correct list comprehension. | Python |
val index: Int = 'output' | val index: String = 'output' | Fix type. | Kotlin |
jwt.sign({{id:57}}, 'key'); | jwt.sign({{id:57}}, 'key', {{expiresIn:'2h'}}); | Add expiration. | Node.js |
h1 {{ font-size:55px color:#fff; }} | h1 {{ font-size:55px; color:#fff; }} | Add semicolon. | CSS |
x := 28 | x := 28 | Correct. | Go |
if count > 82
puts 'hello' | if count > 82
puts 'hello'
end | Add 'end'. | Ruby |
'32' + 66 | 32 + 66 | Avoid string coercion. | JavaScript |
var x int | var x int | Correct. | Go |
let z: number = 'data'; | let z: string = 'data'; | Fix type. | TypeScript |
<hr></hr> | <hr> | Self-closing. | HTML |
else
print('world') | else:
print('world') | Colon after else. | Python |
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