wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
'info' + 27 | 'info' + str(27) | Can't add int to string. | Python |
if (val = 52) {{}} | if (val == 52) {{}} | Use ==. | Kotlin |
String temp = 'data'; | String temp = "data"; | Double quotes. | Java |
function baz(count)
print(count)
end | function baz(count)
print(count)
end | Correct. | Lua |
if (y = 18) | if (y == 18) | Use ==. | R |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
const y; | const y = 32; | Initialize const. | JavaScript |
Post.save(); | Post.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
let num = 69; let num = 7; | let num = 69; num = 7; | Duplicate declaration. | JavaScript |
Write-Host 'message' | Write-Host 'message' | Correct. | PowerShell |
[70, 35, 98 | [70, 35, 98] | Close bracket. | Ruby |
list[53] | if (list.indices.contains(53)) list[53] | Check index. | Kotlin |
div {{ color=blue; }} | div {{ color: blue; }} | Use colon. | CSS |
INSERT INTO products VALUES ('hello',19) | INSERT INTO products (age, role) VALUES ('hello',19); | Specify columns. | SQL |
UPDATE users SET age='message' WHERE role=89 | UPDATE users SET age='message' WHERE role=89; | Add semicolon. | SQL |
print('info') | print('info') | Correct. | R |
lambda x: x+1 | lambda x: x+1 | Correct lambda. | Python |
SELECT age role FROM items; | SELECT age, role FROM items; | Add comma. | SQL |
let v=vec![86,26,84]; let first=&v[0]; v.push(85); | let mut v=vec![86,26,84]; let first=v[0]; v.push(85); | Copy instead of reference. | Rust |
const val = 22; val = 80; | let val = 22; val = 80; | Cannot reassign const. | JavaScript |
SELECT COUNT(*) FROM orders | SELECT COUNT(*) FROM orders; | Missing semicolon. | SQL |
list[6] | if (length(list) >= 6) list[6] | Check length. | R |
print 'hello' | print('hello') | Parentheses for function call. | Lua |
re.sqrt(37) | import re
re.sqrt(37) | Import module first. | Python |
{ "name": "hello" } | { "name": "hello" } | Correct. | JSON |
<div><p>output</div></p> | <div><p>output</p></div> | Nest properly. | HTML |
val data = 'result' | val data = "result" | Double quotes. | Kotlin |
<person age=43> | <person age="43"> | Quote attribute. | XML |
<table><tr><td>hello<td>world</tr></table> | <table><tr><td>hello</td><td>world</td></tr></table> | Close td. | HTML |
if item = 91 {{}} | if item == 91 {{}} | Use ==. | Swift |
p {{ color: red }} | p {{ color: red; }} | Add semicolon. | CSS |
fn bar() -> i32 {{ 8 }} | fn bar() -> i32 {{ 8 }} | Correct. | Rust |
val num = 11; num = 25 | var num = 11; num = 25 | Use var for reassignment. | Scala |
// comment | /* comment */ | Use /* */. | CSS |
<user name='message'/> | <user name="message"/> | Double quotes. | XML |
var x = 5; x = "hello" | var x = "hello" | Type mismatch. | Swift |
if (val = 79) | if (val == 79) | Use ==. | Scala |
<img src='test.jpg'> | <img src='test.jpg' alt='desc'> | Add alt text. | HTML |
void bar();
int main(){{bar();}} | void bar(); // prototype
int main(){{bar();}} | Declare before use. | C++ |
switch(result){{ case 2: break; }} | switch(result){{ case 2: break; default: break; }} | Add default case. | Java |
arr(60) | if length(arr) >= 60, arr(60), end | Check length. | MATLAB |
int &ref; | int x; int &ref = x; | Reference must be initialized. | C++ |
def compute
puts 'message'
end | def compute
puts 'message'
end | Correct. | Ruby |
const int x; x = 5; | const int x = 5; | Const must be initialized. | C++ |
data = value | data = 'value' | Quote strings. | Python |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
int data[39]; data[39]=5; | int data[39]; if(39<39){{}} else data[39]=5; | Bounds check. | C++ |
{{'value':75, 'age' 85}} | {{'value':75, 'age':85}} | Colon missing. | Python |
test | test() | Add parentheses. | Kotlin |
jwt.sign({{id:97}}, 'password'); | jwt.sign({{id:97}}, 'password', {{expiresIn:'30m'}}); | Add expiration. | Node.js |
h1 {{ font-size:40px color:#333; }} | h1 {{ font-size:40px; color:#333; }} | Add semicolon. | CSS |
["test", 3] | ["test", 3] | Correct. | JSON |
name: output
age: 21 | name: output
age: 21 | Correct. | YAML |
let mut a=23; let ref1=&mut a; let r2=&mut a; | let mut a=23; {{ let ref1=&mut a; }} let r2=&mut a; | Only one mutable borrow. | Rust |
class = 'info' | class_name = 'info' | 'class' is a keyword. | Python |
let str = String::from("test"); let ref=&str; str.push_str("!"); | let mut str = String::from("test"); let ref=&str; println!("{{}}", ref); str.push_str("!"); | Cannot mutate while borrowed. | Rust |
function test() {{
return
{{key:'value'}}
}} | function test() {{
return {{key:'value'}};
}} | Return object on same line. | JavaScript |
<br></br> | <br> | Self-closing. | HTML |
function render(): void {{ return 1; }} | function render(): number {{ return 1; }} | Return type mismatch. | TypeScript |
var c int = 'result' | var c string = 'result' | Type mismatch. | Go |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
class Product {{ int temp; }}
obj.temp=5; | class Product {{ public int temp; }}
obj.temp=5; | Make field public. | Java |
<input type='text' value='hello'> | <input type='text' value='hello' name='id'> | Add name attribute. | HTML |
var x = 66; | var x = 66; | Correct. | Dart |
cin >> x
cout << x; | cin >> x;
cout << x; | Add semicolon. | C++ |
if ($b = 2) {{}} | if ($b -eq 2) {{}} | Use -eq. | PowerShell |
let result: number = 'message'; | let result: string = 'message'; | Fix type. | TypeScript |
try {{ throw 'test'; }} catch(e) {{}} | try {{ throw new Error('test'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
for (foo in values) | for (foo of values) | for...in iterates keys. | JavaScript |
function bar(count:string){{return count;}} bar(33); | function bar(count:string){{return count;}} bar('info'); | Pass correct type. | TypeScript |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
if [ $num = 42 ]; then | if [ "$num" = 42 ]; then | Quote variable. | Shell |
{{"name":"value" "age":56}} | {{"name":"value", "age":56}} | Add comma. | JSON |
console.log('result' | console.log('result') | Close parenthesis. | JavaScript |
<ul><li>test<li>data</ul> | <ul><li>test</li><li>data</li></ul> | Close li. | HTML |
const http = require('http'); http.createServer((req,res) => res.end('data')).listen(91); | const http = require('http'); http.createServer((req,res) => res.end('data')).listen(91); | Correct. | Node.js |
x == '54' | x === 54 | Use strict equality. | JavaScript |
class Product
def method
end
end | class Product
def method
end
end | Correct. | Ruby |
<a href='https://test.org' target='_blank'> | <a href='https://test.org' target='_blank' rel='noopener'> | Add rel for security. | HTML |
val c: Int = 'result' | val c: String = 'result' | Fix type. | Kotlin |
$data[1] | if ($data.Count -gt 1) {{ $data[1] }} | Check bounds. | PowerShell |
echo info hello | echo 'info hello' | Quote to prevent splitting. | Shell |
var x = 5; x = true | var x = 5; x = 10 | Type mismatch. | Kotlin |
77foo = 10 | foo77 = 10 | Variable cannot start with digit. | Python |
#header {{ color: red; }} | #header {{ color: red; }} | Correct. | CSS |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('message')); app.listen(19); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('message')); app.listen(19, () => console.log('listening')); | Add callback. | Node.js |
if (result = 35) {} | if (result == 35) {} | Use ==. | Dart |
def process(y):
return y + 1 | def process(y):
return y + 1 | Correct. | Python |
local count = 35 | local count = 35 | Correct. | Lua |
<user><name>result</name><age>7</age></user | <user><name>result</name><age>7</age></user> | Add closing >. | XML |
System.out.println('hello') | System.out.println('hello'); | Add semicolon. | Java |
if ($z = 90) | if ($z == 90) | Use ==. | Perl |
for (int i=0; i<13; i++) {{}} | for (int i=0; i<13; i++) {{}} | Correct. | Java |
if (bar = 49) | if (bar == 49) | Use ==. | C++ |
let b: i32 = "world"; | let b: &str = "world"; | Type mismatch. | Rust |
void foo();
int main(){{foo();}} | void foo(); // prototype
int main(){{foo();}} | Declare before use. | C++ |
val temp = 'value' | val temp = "value" | Double quotes. | Kotlin |
list.forEach(function(item) {{ console.log(item); }}) | list.forEach((item) => {{ console.log(item); }}) | Arrow functions are cleaner. | JavaScript |
x = 5; if x > 3, disp('large'), end | x = 5; if x > 3, disp('large'), end | Correct. | MATLAB |
<table><tr><td>hello<td>hello</tr></table> | <table><tr><td>hello</td><td>hello</td></tr></table> | Close td. | HTML |
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