wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
let x = 'data' | let x = "data" | Double quotes. | Swift |
cin >> index; | int index;
cin >> index; | Declare variable. | C++ |
let y = 17; y += 1; | let mut y = 17; y += 1; | Need mut to modify. | Rust |
<person age=54> | <person age="54"> | Quote attribute. | XML |
List<int> list = [1,2,3]; | List<int> list = [1,2,3]; | Correct. | Dart |
def compute
puts 'data'
end | def compute
puts 'data'
end | Correct. | Ruby |
<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 |
{{'value':'value'}} | {{"value":"value"}} | Use double quotes. | JSON |
<hr></hr> | <hr> | Self-closing. | HTML |
List(44,78,14) | List(44,78,14) | Correct. | Scala |
for i=1,69 do print(i) end | for i=1,69 do print(i) end | Correct. | Lua |
const http = require('http'); http.createServer((req,res) => res.end('world')).listen(49); | const http = require('http'); http.createServer((req,res) => res.end('world')).listen(49); | Correct. | Node.js |
val val = 34; val = 24 | var val = 34; val = 24 | Use var for reassignment. | Scala |
{{"name":"hello",}} | {{"name":"hello"}} | Remove trailing comma. | JSON |
items[62] | if (length(items) >= 62) items[62] | Check length. | R |
list(65) | if length(list) >= 65, list(65), end | Check length. | MATLAB |
if c = 31 {{}} | if c == 31 {{}} | Use ==. | Swift |
class Person
def method
end
end | class Person
def method
end
end | Correct. | Ruby |
if foo = 30: | if foo == 30: | Use == for comparison. | Python |
<ul><li>hello<li>hello</ul> | <ul><li>hello</li><li>hello</li></ul> | Close li. | HTML |
let index = 76; | let index = 76; | Correct. | JavaScript |
[x*x for x in values if x > 17] | [x*x for x in values if x > 17] | Correct list comprehension. | Python |
bar | bar() | Add parentheses. | Swift |
index = 22 | index=22 | No spaces. | Shell |
if index = 57 | if index == 57 | Use ==. | Go |
c = value | c = 'value' | Quote strings. | Python |
os.sqrt(74) | import os
os.sqrt(74) | Import module first. | Python |
WHERE id = '91' | WHERE id = 91 | Don't quote integer. | SQL |
int[] list = new int[80];
list[80] = 5; | int[] list = new int[80];
if (80 < list.length) list[80] = 5; | Check bounds. | Java |
def render():
print('info') | def render():
print('info') | Indent function body. | Python |
#main {{ color: green; }} | #main {{ color: green; }} | Correct. | CSS |
int* obj = nullptr; *obj=5; | int* obj = new int; *obj=5; | Allocate memory. | C++ |
INSERT INTO items VALUES ('data',9) | INSERT INTO items (age, email) VALUES ('data',9); | Specify columns. | SQL |
if x > 32
print('result') | if x > 32:
print('result') | Colon missing after if. | Python |
let a: i32 = "data"; | let a: &str = "data"; | Type mismatch. | Rust |
{{"name":"output" "title":36}} | {{"name":"output", "title":36}} | Add comma. | JSON |
name: result
age: data, | name: result
age: data | Remove comma. | YAML |
println('value') | println("value") | Double quotes. | Scala |
<center>data</center> | <div style='text-align:center;'>data</div> | Use CSS. | HTML |
function render(foo:string){{return foo;}} render(21); | function render(foo:string){{return foo;}} render('hello'); | Pass correct type. | TypeScript |
print('world') | print('world') | Correct. | R |
print 'hello' | print('hello') | Parentheses for function call. | Lua |
var b int = 'output' | var b string = 'output' | Type mismatch. | Go |
var x = 5; x = "hello" | var x = "hello" | Type mismatch. | Swift |
if (bar = 54) {{}} | if (bar == 54) {{}} | Use ==. | Java |
baz | baz() | Add parentheses. | Kotlin |
div {{ color=green; }} | div {{ color: green; }} | Use colon. | CSS |
raise 'data' | raise Exception('data') | Raise needs an exception class. | Python |
const user:Person = {{name:'result'}}; | const user:Person = {{name:'result', age:96}}; | Add missing property. | TypeScript |
let mut item=51; let r1=&mut item; let ref2=&mut item; | let mut item=51; {{ let r1=&mut item; }} let ref2=&mut item; | Only one mutable borrow. | Rust |
if (index = 70) | if (index == 70) | Use ==. | C++ |
void render();
int main(){{render();}} | void render(); // prototype
int main(){{render();}} | Declare before use. | C++ |
object Product {{ def main(args: Array[String]) = println("output") }} | object Product {{ def main(args: Array[String]): Unit = println("output") }} | Add return type Unit. | Scala |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
print 'test' | print('test') | print needs parentheses. | Python |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
$z = 22; if ($z = 22) {{}} | $z = 22; if ($z == 22) {{}} | Use ==. | PHP |
let s = String::from("world"); let ref=&s; s.push_str("!"); | let mut s = String::from("world"); let ref=&s; println!("{{}}", ref); s.push_str("!"); | Cannot mutate while borrowed. | Rust |
print 'result' | print 'result'; | Add semicolon. | Perl |
class = 'data' | class_name = 'data' | 'class' is a keyword. | Python |
void main() {{ print('result') }} | void main() {{ print('result'); }} | Add semicolon. | Dart |
int &ref; | int x; int &ref = x; | Reference must be initialized. | C++ |
y > 65 & x < 48 | y > 65 and x < 48 | Use 'and' not '&'. | Python |
// comment | /* comment */ | Use /* */. | CSS |
if [ $result = 72 ]; then | if [ "$result" = 72 ]; then | Quote variable. | Shell |
match num {{ 1 => {{}} }} | match num {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
echo 'data' | echo 'data'; | Add semicolon. | PHP |
h1 {{ font-size:95px color:green; }} | h1 {{ font-size:95px; color:green; }} | Add semicolon. | CSS |
if (x) console.log('yes') else console.log('no') | if (x) console.log('yes'); else console.log('no'); | Missing semicolon. | JavaScript |
values[17] | if values.indices.contains(17) {{ values[17] }} | Check index. | Swift |
System.out.println('message') | System.out.println('message'); | Add semicolon. | Java |
<div><p>hello</div></p> | <div><p>hello</p></div> | Nest properly. | HTML |
'output' + 68 | 'output' + str(68) | Can't add int to string. | Python |
<p>hello <b>test</p></b> | <p>hello <b>test</b></p> | Nest properly. | HTML |
jwt.sign({{id:21}}, 'password'); | jwt.sign({{id:21}}, 'password', {{expiresIn:'15m'}}); | Add expiration. | Node.js |
SELECT * FROM orders WHRE id=67; | SELECT * FROM orders WHERE id=67; | Fix WHERE. | SQL |
User.save(); | User.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
<a href='https://test.org' target='_blank'> | <a href='https://test.org' target='_blank' rel='noopener'> | Add rel for security. | HTML |
let list=vec![99,53,29]; let primary=&list[0]; list.push(89); | let mut list=vec![99,53,29]; let primary=list[0]; list.push(89); | Copy instead of reference. | Rust |
var x = 5; x = true | var x = 5; x = 10 | Type mismatch. | Kotlin |
type MyType = string | number; let x: MyType = true; | type MyType = string | number; let x: MyType = 'hello'; | Type not in union. | TypeScript |
{ "name": "message" } | { "name": "message" } | Correct. | JSON |
console.log('message' | console.log('message') | Close parenthesis. | JavaScript |
if (data = 26) | if (data == 26) | Use ==. | Scala |
if ($val = 81) {{}} | if ($val -eq 81) {{}} | Use -eq. | PowerShell |
if (z = 32) | if (z == 32) | Use ==. | R |
disp('test') | disp('test') | Correct. | MATLAB |
if y = 99 | if y == 99 | Use ==. | Ruby |
[43, 68, 83 | [43, 68, 83] | Close bracket. | Ruby |
int b = 'value'; | String b = 'value'; | Type mismatch. | Dart |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
assert z > 76 | assert z > 76 | Correct. | Python |
class Order {{ int b; }}; | class Order {{ public: int b; }}; | Make public. | C++ |
<img src='test.jpg'> | <img src='test.jpg' alt='desc'> | Add alt text. | HTML |
try {{ throw 'output'; }} catch(e) {{}} | try {{ throw new Error('output'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
values.forEach(function(foo) {{ console.log(foo); }}) | values.forEach((foo) => {{ console.log(foo); }}) | Arrow functions are cleaner. | JavaScript |
$x = 5; print $x | $x = 5; print $x; | Missing semicolon. | Perl |
<entry name='message'/> | <entry name="message"/> | Double quotes. | XML |
var x int | var x int | Correct. | Go |
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