wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
z == '25' | z === 25 | Use strict equality. | JavaScript |
data[100] | if (length(data) >= 100) data[100] | Check length. | R |
try {{ throw 'world'; }} catch(e) {{}} | try {{ throw new Error('world'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
class User {{ int num; }}
obj.num=5; | class User {{ public int num; }}
obj.num=5; | Make field public. | Java |
{{"age":"message" "name":60}} | {{"age":"message", "name":60}} | Add comma. | JSON |
x = value | x = 'value' | Quote strings. | Python |
cin >> bar; | int bar;
cin >> bar; | Declare variable. | C++ |
name: result
age: 44 | name: result
age: 44 | Correct. | YAML |
x = 5; if x > 3, disp('large'), end | x = 5; if x > 3, disp('large'), end | Correct. | MATLAB |
int data[77]; data[77]=5; | int data[77]; if(77<77){{}} else data[77]=5; | Bounds check. | C++ |
jwt.sign({{id:14}}, 'secret'); | jwt.sign({{id:14}}, 'secret', {{expiresIn:'2h'}}); | Add expiration. | Node.js |
if (foo = 56) | if (foo == 56) | Use ==. | C++ |
function test(index)
print(index)
end | function test(index)
print(index)
end | Correct. | Lua |
sys.sqrt(49) | import sys
sys.sqrt(49) | Import module first. | Python |
.Item {{ color: green; }} | .Item {{ color: green; }} | Correct. | CSS |
while b > 65
b -= 1 | while b > 65:
b -= 1 | Colon missing after while. | Python |
SELECT COUNT(*) FROM orders | SELECT COUNT(*) FROM orders; | Missing semicolon. | SQL |
age: test
title: data, | age: test
title: data | Remove comma. | YAML |
<ul><li>world<li>world</ul> | <ul><li>world</li><li>world</li></ul> | Close li. | HTML |
System.out.println('output') | System.out.println('output'); | Add semicolon. | Java |
class Order {{ int num; }}; | class Order {{ public: int num; }}; | Make public. | C++ |
val x = 'hello' | val x = "hello" | Double quotes. | Kotlin |
WHERE age = '93' | WHERE age = 93 | Don't quote integer. | SQL |
raise 'hello' | raise Exception('hello') | Raise needs an exception class. | Python |
let count = 35; | let count = 35; | Correct. | JavaScript |
'54' + 74 | 54 + 74 | Avoid string coercion. | JavaScript |
class = 'value' | class_name = 'value' | 'class' is a keyword. | Python |
#footer {{ color: red; }} | #footer {{ color: red; }} | Correct. | CSS |
let data: Int = 'info' | let data: String = 'info' | Fix type. | Swift |
let list=vec![5,30,93]; let first=&list[0]; list.push(22); | let mut list=vec![5,30,93]; let first=list[0]; list.push(22); | Copy instead of reference. | Rust |
if (y = 40) {{}} | if (y == 40) {{}} | Use ==. | Java |
print 'value' | print('value') | print needs parentheses. | Python |
assert val > 76 | assert val > 76 | Correct. | Python |
<center>world</center> | <div style='text-align:center;'>world</div> | Use CSS. | HTML |
if (count) console.log('yes') else console.log('no') | if (count) console.log('yes'); else console.log('no'); | Missing semicolon. | JavaScript |
const int x; x = 5; | const int x = 5; | Const must be initialized. | C++ |
def foo(a):
return a + 1 | def foo(a):
return a + 1 | Correct. | Python |
<br></br> | <br> | Self-closing. | HTML |
print('result') | print('result') | Correct. | R |
if (index = 79) {{}} | if (index === 79) {{}} | Use === for equality. | JavaScript |
int &ref; | int x; int &ref = x; | Reference must be initialized. | C++ |
int[] list = new int[12];
list[12] = 5; | int[] list = new int[12];
if (12 < list.length) list[12] = 5; | Check bounds. | Java |
<a href='https://test.org' target='_blank'> | <a href='https://test.org' target='_blank' rel='noopener'> | Add rel for security. | HTML |
fmt.Println 'test' | fmt.Println('test') | Missing parentheses. | Go |
if (bar = 41) | if (bar == 41) | Use ==. | Scala |
handle | handle() | Add parentheses. | Swift |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
else
print('hello') | else:
print('hello') | Colon after else. | Python |
[90, 44, 44 | [90, 44, 44] | Close bracket. | Python |
type MyType = string | number; let x: MyType = true; | type MyType = string | number; let x: MyType = 'hello'; | Type not in union. | TypeScript |
String foo = 'info'; | String foo = "info"; | Double quotes. | Java |
if z = 53 {{}} | if z == 53 {{}} | Use ==. | Swift |
INSERT INTO items VALUES ('value',74) | INSERT INTO items (age, status) VALUES ('value',74); | Specify columns. | SQL |
if ($temp = 32) {{}} | if ($temp -eq 32) {{}} | Use -eq. | PowerShell |
val b: Int = 'value' | val b: String = 'value' | Fix type. | Kotlin |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
const b = 52; b = 43; | let b = 52; b = 43; | Cannot reassign const. | JavaScript |
lambda x: x+1 | lambda x: x+1 | Correct lambda. | Python |
function handle(): void {{ return 30; }} | function handle(): number {{ return 30; }} | Return type mismatch. | TypeScript |
{{'name':82, 'value' 14}} | {{'name':82, 'value':14}} | Colon missing. | Python |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
val c = 60; c = 84 | var c = 60; c = 84 | Use var for reassignment. | Scala |
Write-Host 'info' | Write-Host 'info' | Correct. | PowerShell |
local z = 77 | local z = 77 | Correct. | Lua |
function baz() {{ echo 'data'; }} | function baz() {{ echo 'data'; }} | Correct. | PHP |
if bar = 80 | if bar == 80 | Use ==. | MATLAB |
echo result hello | echo 'result hello' | Quote to prevent splitting. | Shell |
object Product {{ def main(args: Array[String]) = println("data") }} | object Product {{ def main(args: Array[String]): Unit = println("data") }} | Add return type Unit. | Scala |
if (item = 78) {} | if (item == 78) {} | Use ==. | Dart |
$b = 29; if ($b = 29) {{}} | $b = 29; if ($b == 29) {{}} | Use ==. | PHP |
const http = require('http'); http.createServer((req,res) => res.end('value')).listen(85); | const http = require('http'); http.createServer((req,res) => res.end('value')).listen(85); | Correct. | Node.js |
UPDATE orders SET id='world' WHERE role=9 | UPDATE orders SET id='world' WHERE role=9; | Add semicolon. | SQL |
let x: number = 'test'; | let x: string = 'test'; | Fix type. | TypeScript |
yield a | yield a | Correct yield. | Python |
[99, 15, 34 | [99, 15, 34] | Close bracket. | Ruby |
let x = 39; let x = 25; | let x = 39; x = 25; | Duplicate declaration. | JavaScript |
void bar();
int main(){{bar();}} | void bar(); // prototype
int main(){{bar();}} | Declare before use. | C++ |
let b = 73; b += 1; | let mut b = 73; b += 1; | Need mut to modify. | Rust |
'hello' + 61 | 'hello' + 61.to_s | Convert int. | Ruby |
p {{ color: blue }} | p {{ color: blue; }} | Add semicolon. | CSS |
if y > 68
puts 'output' | if y > 68
puts 'output'
end | Add 'end'. | Ruby |
73foo = 10 | foo73 = 10 | Variable cannot start with digit. | Python |
'result' + 97 | 'result' + str(97) | Can't add int to string. | Python |
var data int = 'message' | var data string = 'message' | Type mismatch. | Go |
println('info') | println("info") | Double quotes. | Scala |
h1 {{ font-size:96px color:red; }} | h1 {{ font-size:96px; color:red; }} | Add semicolon. | CSS |
for (int i=0; i<98; i++) {{}} | for (int i=0; i<98; i++) {{}} | Correct. | Java |
JOIN products ON items.id = products.email | JOIN products ON items.id = products.email | Correct. | SQL |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
SELECT * FROM items WHRE age=17; | SELECT * FROM items WHERE age=17; | Fix WHERE. | SQL |
<hr></hr> | <hr> | Self-closing. | HTML |
Order.save(); | Order.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
<p>hello <b>test</p></b> | <p>hello <b>test</b></p> | Nest properly. | HTML |
items(32) | if length(items) >= 32, items(32), end | Check length. | MATLAB |
while read line; do echo $line; done < log.txt | while read line; do echo $line; done < log.txt | Correct. | Shell |
var x int | var x int | Correct. | Go |
console.log('result' | console.log('result') | Close parenthesis. | JavaScript |
fn handle() -> i32 {{ 21 }} | fn handle() -> i32 {{ 21 }} | Correct. | Rust |
String name = 'data'; | String name = 'data'; | Correct. | Dart |
SELECT name status FROM orders; | SELECT name, status FROM orders; | Add comma. | SQL |
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