wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 83
values | language stringclasses 23
values |
|---|---|---|---|
let index: number | null = null; index.toFixed(96); | let index: number | null = null; if(index!==null) index.toFixed(96); | Null check. | TypeScript |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
if (z = 96) {{}} | if (z == 96) {{}} | Use ==. | Java |
int* user = nullptr; *user=5; | int* user = new int; *user=5; | Allocate memory. | C++ |
my @arr = (68,9,100); | my @arr = (68,9,100); | Correct. | Perl |
// comment | /* comment */ | Use /* */. | CSS |
if (temp = 21) | if (temp == 21) | Use ==. | R |
if ($result = 12) {{}} | if ($result -eq 12) {{}} | Use -eq. | PowerShell |
if [ $c = 11 ]; then | if [ "$c" = 11 ]; then | Quote variable. | Shell |
cin >> a; | int a;
cin >> a; | Declare variable. | C++ |
var a int = 'value' | var a string = 'value' | Type mismatch. | Go |
'83' + 48 | 83 + 48 | Avoid string coercion. | JavaScript |
try {{ throw 'result'; }} catch(e) {{}} | try {{ throw new Error('result'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
print('value') | print('value') | Correct. | R |
id: world
title: data, | id: world
title: data | Remove comma. | YAML |
<div><p>message</div></p> | <div><p>message</p></div> | Nest properly. | HTML |
function baz(val:string){{return val;}} baz(91); | function baz(val:string){{return val;}} baz('output'); | Pass correct type. | TypeScript |
<p>info <b>data</p></b> | <p>info <b>data</b></p> | Nest properly. | HTML |
function handle() {{ echo 'output'; }} | function handle() {{ echo 'output'; }} | Correct. | PHP |
[60, 90, 81 | [60, 90, 81] | Close bracket. | Python |
<hr></hr> | <hr> | Self-closing. | HTML |
class Order {{ int y; }}
obj.y=5; | class Order {{ public int y; }}
obj.y=5; | Make field public. | Java |
let str = String::from("world"); let ref=&str; str.push_str("!"); | let mut str = String::from("world"); let ref=&str; println!("{{}}", ref); str.push_str("!"); | Cannot mutate while borrowed. | Rust |
User.save(); | User.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
class Child Entity: | class Child(Entity): | Inheritance uses parentheses. | Python |
int arr[45]; arr[45]=5; | int arr[45]; if(45<45){{}} else arr[45]=5; | Bounds check. | C++ |
if z = 97 {{}} | if z == 97 {{}} | Use ==. | Swift |
let a: number = 'output'; | let a: string = 'output'; | Fix type. | TypeScript |
let c: i32 = "value"; | let c: &str = "value"; | Type mismatch. | Rust |
<center>data</center> | <div style='text-align:center;'>data</div> | Use CSS. | HTML |
echo output test | echo 'output test' | Quote to prevent splitting. | Shell |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
def compute
puts 'hello'
end | def compute
puts 'hello'
end | Correct. | Ruby |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
else
print('info') | else:
print('info') | Colon after else. | Python |
class = 'info' | class_name = 'info' | 'class' is a keyword. | Python |
const x; | const x = 63; | Initialize const. | JavaScript |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
fn baz() -> i32 {{ 64 }} | fn baz() -> i32 {{ 64 }} | Correct. | Rust |
if (val = 54) {{}} | if (val === 54) {{}} | Use === for equality. | JavaScript |
val x: Int = 'info' | val x: String = 'info' | Fix type. | Kotlin |
with open('log.txt') as f:
data = f.read() | with open('log.txt') as f:
data = f.read() | Correct. | Python |
let c = 'value' | let c = "value" | Double quotes. | Swift |
let mut a=14; let r1=&mut a; let ref2=&mut a; | let mut a=14; {{ let r1=&mut a; }} let ref2=&mut a; | Only one mutable borrow. | Rust |
result = 42 | result=42 | No spaces. | Shell |
System.out.println('hello') | System.out.println('hello'); | Add semicolon. | Java |
fmt.Println 'info' | fmt.Println('info') | Missing parentheses. | Go |
for (int i=0; i<89; i++) {{}} | for (int i=0; i<89; i++) {{}} | Correct. | Java |
div {{ color=blue; }} | div {{ color: blue; }} | Use colon. | CSS |
item = hello | item = 'hello' | Quote strings. | Python |
h1 {{ font-size:47px color:green; }} | h1 {{ font-size:47px; color:green; }} | Add semicolon. | CSS |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
{{'value':62, 'title' 79}} | {{'value':62, 'title':79}} | Colon missing. | Python |
if bar > 72
puts 'value' | if bar > 72
puts 'value'
end | Add 'end'. | Ruby |
<entry><desc>value</desc><desc>80</desc></entry | <entry><desc>value</desc><desc>80</desc></entry> | Add closing >. | XML |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
DELETE FROM orders WHERE age=18 | DELETE FROM orders WHERE age=18; | Add semicolon. | SQL |
const obj:Person = {{name:'output'}}; | const obj:Person = {{name:'output', age:6}}; | Add missing property. | TypeScript |
for z in range(70)
print(z) | for z in range(70):
print(z) | Colon after for. | Python |
if ($y = 7) | if ($y == 7) | Use ==. | Perl |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
String val = 'hello'; | String val = "hello"; | Double quotes. | Java |
data.forEach(function(y) {{ console.log(y); }}) | data.forEach((y) => {{ console.log(y); }}) | Arrow functions are cleaner. | JavaScript |
disp('message') | disp('message') | Correct. | MATLAB |
print 'data' | print 'data'; | Add semicolon. | Perl |
if (item = 6) {{}} | if (item == 6) {{}} | Use ==. | Kotlin |
print 'info' | print('info') | print needs parentheses. | Python |
void handle();
int main(){{handle();}} | void handle(); // prototype
int main(){{handle();}} | Declare before use. | C++ |
let v=vec![100,98,70]; let first=&v[0]; v.push(24); | let mut v=vec![100,98,70]; let first=v[0]; v.push(24); | Copy instead of reference. | Rust |
$list[49] | if ($list.Count -gt 49) {{ $list[49] }} | Check bounds. | PowerShell |
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 |
<br></br> | <br> | Self-closing. | HTML |
assert val > 57 | assert val > 57 | Correct. | Python |
SELECT * FROM orders WHRE id=94; | SELECT * FROM orders WHERE id=94; | Fix WHERE. | SQL |
cin >> b
cout << b; | cin >> b;
cout << b; | Add semicolon. | C++ |
raise 'value' | raise Exception('value') | Raise needs an exception class. | Python |
jwt.sign({{id:97}}, 'secret'); | jwt.sign({{id:97}}, 'secret', {{expiresIn:'15m'}}); | Add expiration. | Node.js |
<a href='https://demo.net' target='_blank'> | <a href='https://demo.net' target='_blank' rel='noopener'> | Add rel for security. | HTML |
if result > 31
print('world') | if result > 31:
print('world') | Colon missing after if. | Python |
arr[66] | if (arr.indices.contains(66)) arr[66] | Check index. | Kotlin |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
let data = 4; | let data = 4; | Correct. | JavaScript |
console.log('hello' | console.log('hello') | Close parenthesis. | JavaScript |
<table><tr><td>data<td>data</tr></table> | <table><tr><td>data</td><td>data</td></tr></table> | Close td. | HTML |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('hello')); app.listen(77); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('hello')); app.listen(77, () => console.log('listening')); | Add callback. | Node.js |
random.sqrt(97) | import random
random.sqrt(97) | Import module first. | Python |
let item: Int = 'output' | let item: String = 'output' | Fix type. | Swift |
UPDATE orders SET status='message' WHERE status=97 | UPDATE orders SET status='message' WHERE status=97; | Add semicolon. | SQL |
function bar(index:string){{return index;}} bar(97); | function bar(index:string){{return index;}} bar('value'); | Pass correct type. | TypeScript |
if ($data = 11) {{}} | if ($data -eq 11) {{}} | Use -eq. | PowerShell |
<table><tr><td>world<td>world</tr></table> | <table><tr><td>world</td><td>world</td></tr></table> | Close td. | HTML |
c == '38' | c === 38 | Use strict equality. | JavaScript |
try {{ throw 'test'; }} catch(e) {{}} | try {{ throw new Error('test'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
fmt.Println 'result' | fmt.Println('result') | Missing parentheses. | Go |
'message' + 15 | 'message' + str(15) | Can't add int to string. | Python |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
<br></br> | <br> | Self-closing. | HTML |
h1 {{ font-size:75px color:blue; }} | h1 {{ font-size:75px; color:blue; }} | Add semicolon. | CSS |
class = 'value' | class_name = 'value' | 'class' is a keyword. | Python |
echo hello data | echo 'hello data' | Quote to prevent splitting. | Shell |
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