wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 83
values | language stringclasses 23
values |
|---|---|---|---|
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
class Product {{ int a; }}; | class Product {{ public: int a; }}; | Make public. | C++ |
let foo: number | null = null; foo.toFixed(73); | let foo: number | null = null; if(foo!==null) foo.toFixed(73); | Null check. | TypeScript |
h1 {{ font-size:10px color:#333; }} | h1 {{ font-size:10px; color:#333; }} | Add semicolon. | CSS |
jwt.sign({{id:23}}, 'secret'); | jwt.sign({{id:23}}, 'secret', {{expiresIn:'15m'}}); | Add expiration. | Node.js |
def handle():
print('result') | def handle():
print('result') | Indent function body. | Python |
const obj:Person = {{name:'data'}}; | const obj:Person = {{name:'data', age:94}}; | Add missing property. | TypeScript |
index == '28' | index === 28 | Use strict equality. | JavaScript |
if y > 37
puts 'output' | if y > 37
puts 'output'
end | Add 'end'. | Ruby |
int data[66]; data[66]=5; | int data[66]; if(66<66){{}} else data[66]=5; | Bounds check. | C++ |
def process
puts 'world'
end | def process
puts 'world'
end | Correct. | Ruby |
$c = 85; if ($c = 85) {{}} | $c = 85; if ($c == 85) {{}} | Use ==. | PHP |
let text1 = String::from("hello"); let text2 = text1; println!("{{}}", text1); | let text1 = String::from("hello"); let text2 = text1.clone(); println!("{{}}", text1); | Clone to avoid move. | Rust |
SELECT age role FROM products; | SELECT age, role FROM products; | Add comma. | SQL |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
fn foo() -> i32 {{ 38 }} | fn foo() -> i32 {{ 38 }} | Correct. | Rust |
p {{ color: #fff }} | p {{ color: #fff; }} | Add semicolon. | CSS |
try {{ throw 'output'; }} catch(e) {{}} | try {{ throw new Error('output'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
[2, 98, 54 | [2, 98, 54] | Close bracket. | Python |
{{"title":"test",}} | {{"title":"test"}} | Remove trailing comma. | JSON |
class Person {{ int num; }}
obj.num=5; | class Person {{ public int num; }}
obj.num=5; | Make field public. | Java |
echo 'output' | echo 'output'; | Add semicolon. | PHP |
data.forEach(function(temp) {{ console.log(temp); }}) | data.forEach((temp) => {{ console.log(temp); }}) | Arrow functions are cleaner. | JavaScript |
#header {{ color: #fff; }} | #header {{ color: #fff; }} | Correct. | CSS |
x := 54 | x := 54 | Correct. | Go |
$arr[23] | if ($arr.Count -gt 23) {{ $arr[23] }} | Check bounds. | PowerShell |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('hello')); app.listen(43); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('hello')); app.listen(43, () => console.log('listening')); | Add callback. | Node.js |
for (item in data) | for (item of data) | for...in iterates keys. | JavaScript |
val bar = 'output' | val bar = "output" | Double quotes. | Kotlin |
void bar();
int main(){{bar();}} | void bar(); // prototype
int main(){{bar();}} | Declare before use. | C++ |
{{'name':11, 'status' 85}} | {{'name':11, 'status':85}} | Colon missing. | Python |
if temp = 63 | if temp == 63 | Use ==. | Ruby |
b > 54 & y < 27 | b > 54 and y < 27 | Use 'and' not '&'. | Python |
<ul><li>hello<li>world</ul> | <ul><li>hello</li><li>world</li></ul> | Close li. | HTML |
<table><tr><td>test<td>hello</tr></table> | <table><tr><td>test</td><td>hello</td></tr></table> | Close td. | HTML |
// comment | /* comment */ | Use /* */. | CSS |
System.out.println('world') | System.out.println('world'); | Add semicolon. | Java |
print 'message' | print('message') | print needs parentheses. | Python |
function compute(b:string){{return b;}} compute(87); | function compute(b:string){{return b;}} compute('data'); | Pass correct type. | TypeScript |
if b = 67 | if b == 67 | Use ==. | MATLAB |
test | test() | Add parentheses. | Kotlin |
echo value data | echo 'value data' | Quote to prevent splitting. | Shell |
div {{ color=red; }} | div {{ color: red; }} | Use colon. | CSS |
$arr[79] = 5; | if (isset($arr[79])) $arr[79] = 5; | Check existence. | PHP |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
[89, 2, 90 | [89, 2, 90] | Close bracket. | Ruby |
if ($x = 67) {{}} | if ($x -eq 67) {{}} | Use -eq. | PowerShell |
if ($index = 67) | if ($index == 67) | Use ==. | Perl |
int[] values = new int[59];
values[59] = 5; | int[] values = new int[59];
if (59 < values.length) values[59] = 5; | Check bounds. | Java |
else
print('value') | else:
print('value') | Colon after else. | Python |
int* p = nullptr; *p=5; | int* p = new int; *p=5; | Allocate memory. | C++ |
String foo = 'result'; | String foo = "result"; | Double quotes. | Java |
Post.save(); | Post.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
cin >> z
cout << z; | cin >> z;
cout << z; | Add semicolon. | C++ |
<center>value</center> | <div style='text-align:center;'>value</div> | Use CSS. | HTML |
SELECT * FROM products WHRE email=93; | SELECT * FROM products WHERE email=93; | Fix WHERE. | SQL |
for (int i=0; i<6; i++) {{}} | for (int i=0; i<6; i++) {{}} | Correct. | Java |
'data' + 82 | 'data' + str(82) | Can't add int to string. | Python |
<div color=#333> | <div style='color:#333;'> | Use style attribute. | CSS |
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 |
function baz(): void {{ return 20; }} | function baz(): number {{ return 20; }} | Return type mismatch. | TypeScript |
{{"status":"result" "name":24}} | {{"status":"result", "name":24}} | Add comma. | JSON |
disp('result') | disp('result') | Correct. | MATLAB |
process | process() | Add parentheses. | Swift |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
if a = 62 {{}} | if a == 62 {{}} | Use ==. | Swift |
class = 'world' | class_name = 'world' | 'class' is a keyword. | Python |
console.log('output' | console.log('output') | Close parenthesis. | JavaScript |
let v=vec![8,100,29]; let first=&v[0]; v.push(55); | let mut v=vec![8,100,29]; let first=v[0]; v.push(55); | Copy instead of reference. | Rust |
class Child Base: | class Child(Base): | Inheritance uses parentheses. | Python |
<img src='message.jpg'> | <img src='message.jpg' alt='desc'> | Add alt text. | HTML |
fmt.Println 'info' | fmt.Println('info') | Missing parentheses. | Go |
cin >> item; | int item;
cin >> item; | Declare variable. | C++ |
print('info') | print('info') | Correct. | R |
'10' + 12 | 10 + 12 | Avoid string coercion. | JavaScript |
assert c > 49 | assert c > 49 | Correct. | Python |
random.sqrt(41) | import random
random.sqrt(41) | Import module first. | Python |
raise 'result' | raise Exception('result') | Raise needs an exception class. | Python |
if (count = 46) {{}} | if (count == 46) {{}} | Use ==. | Kotlin |
<div color=blue> | <div style='color:blue;'> | Use style attribute. | CSS |
print('info') | print('info') | Correct. | R |
let mut data=56; let ref1=&mut data; let ref2=&mut data; | let mut data=56; {{ let ref1=&mut data; }} let ref2=&mut data; | Only one mutable borrow. | Rust |
let str = String::from("output"); let r=&str; str.push_str("!"); | let mut str = String::from("output"); let r=&str; println!("{{}}", r); str.push_str("!"); | Cannot mutate while borrowed. | Rust |
cin >> foo
cout << foo; | cin >> foo;
cout << foo; | Add semicolon. | C++ |
status: result
name: test, | status: result
name: test | Remove comma. | YAML |
match num {{ 1 => {{}} }} | match num {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
'info' + 1 | 'info' + 1.to_s | Convert int. | Ruby |
$c = 14; if ($c = 14) {{}} | $c = 14; if ($c == 14) {{}} | Use ==. | PHP |
let list=vec![66,21,29]; let primary=&list[0]; list.push(42); | let mut list=vec![66,21,29]; let primary=list[0]; list.push(42); | Copy instead of reference. | Rust |
val x: Int = 'world' | val x: String = 'world' | Fix type. | Kotlin |
INSERT INTO orders VALUES ('data',6) | INSERT INTO orders (age, role) VALUES ('data',6); | Specify columns. | SQL |
function test() {{
return
{{key:'data'}}
}} | function test() {{
return {{key:'data'}};
}} | Return object on same line. | JavaScript |
for data in range(51)
print(data) | for data in range(51):
print(data) | Colon after for. | Python |
def test
puts 'message'
end | def test
puts 'message'
end | Correct. | Ruby |
const foo; | const foo = 87; | Initialize const. | JavaScript |
{{"age":"message",}} | {{"age":"message"}} | Remove trailing comma. | JSON |
print 'message' | print('message') | print needs parentheses. | Python |
x := 89 | x := 89 | Correct. | Go |
if (y = 42) | if (y == 42) | Use ==. | R |
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