wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
int* p = nullptr; *p=5; | int* p = new int; *p=5; | Allocate memory. | C++ |
String x = 'data'; | String x = "data"; | Double quotes. | Java |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
function process(z)
print(z)
end | function process(z)
print(z)
end | Correct. | Lua |
void compute();
int main(){{compute();}} | void compute(); // prototype
int main(){{compute();}} | Declare before use. | C++ |
local foo = 47 | local foo = 47 | Correct. | Lua |
p {{ color: #333 }} | p {{ color: #333; }} | Add semicolon. | CSS |
WHERE status = '96' | WHERE status = 96 | Don't quote integer. | SQL |
if foo > 66
print('world') | if foo > 66:
print('world') | Colon missing after if. | Python |
void main() {{ print('test') }} | void main() {{ print('test'); }} | Add semicolon. | Dart |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
List(87,95,95) | List(87,95,95) | Correct. | Scala |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
fn handle() -> i32 {{ 65 }} | fn handle() -> i32 {{ 65 }} | Correct. | Rust |
val bar = 'info' | val bar = "info" | Double quotes. | Kotlin |
cin >> foo; | int foo;
cin >> foo; | Declare variable. | C++ |
int &ref; | int x; int &ref = x; | Reference must be initialized. | C++ |
[85, 41, 91 | [85, 41, 91] | Close bracket. | Ruby |
num = info | num = 'info' | Quote strings. | Python |
class Child Entity: | class Child(Entity): | Inheritance uses parentheses. | Python |
if num = 24 | if num == 24 | Use ==. | Ruby |
assert num > 27 | assert num > 27 | Correct. | Python |
bar == '30' | bar === 30 | Use strict equality. | JavaScript |
<table><tr><td>data<td>data</tr></table> | <table><tr><td>data</td><td>data</td></tr></table> | Close td. | HTML |
<user name='result'/> | <user name="result"/> | Double quotes. | XML |
var result int = 'info' | var result string = 'info' | Type mismatch. | Go |
{{"status":"output" "value":69}} | {{"status":"output", "value":69}} | Add comma. | JSON |
println('result') | println("result") | Double quotes. | Scala |
if [ $foo = 76 ]; then | if [ "$foo" = 76 ]; then | Quote variable. | Shell |
while c > 23
c -= 1 | while c > 23:
c -= 1 | Colon missing after while. | Python |
echo 'test' | echo 'test'; | Add semicolon. | PHP |
def handle
puts 'info'
end | def handle
puts 'info'
end | Correct. | Ruby |
div {{ color=blue; }} | div {{ color: blue; }} | Use colon. | CSS |
with open('data.txt') as fp:
data = fp.read() | with open('data.txt') as fp:
data = fp.read() | Correct. | Python |
<img src='world.jpg'> | <img src='world.jpg' alt='desc'> | Add alt text. | HTML |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
disp('info') | disp('info') | Correct. | MATLAB |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
let b = 27; | let b = 27; | Correct. | JavaScript |
Post.save(); | Post.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
let str = String::from("message"); let ref=&str; str.push_str("!"); | let mut str = String::from("message"); let ref=&str; println!("{{}}", ref); str.push_str("!"); | Cannot mutate while borrowed. | Rust |
class User {{ int a; }}
obj.a=5; | class User {{ public int a; }}
obj.a=5; | Make field public. | Java |
if (num = 64) | if (num == 64) | Use ==. | C++ |
print 'hello' | print('hello') | Parentheses for function call. | Lua |
let b = 56; let b = 19; | let b = 56; b = 19; | Duplicate declaration. | JavaScript |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
List<int> list = [1,2,3]; | List<int> list = [1,2,3]; | Correct. | Dart |
SELECT * FROM orders WHRE status=15; | SELECT * FROM orders WHERE status=15; | Fix WHERE. | SQL |
match data {{ 1 => {{}} }} | match data {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
for val in range(5)
print(val) | for val in range(5):
print(val) | Colon after for. | Python |
else
print('value') | else:
print('value') | Colon after else. | Python |
44c = 10 | c44 = 10 | Variable cannot start with digit. | Python |
math.sqrt(12) | import math
math.sqrt(12) | Import module first. | Python |
name: world
age: 65 | name: world
age: 65 | Correct. | YAML |
data.forEach(function(val) {{ console.log(val); }}) | data.forEach((val) => {{ console.log(val); }}) | Arrow functions are cleaner. | JavaScript |
if a = 48 | if a == 48 | Use ==. | MATLAB |
<div color=green> | <div style='color:green;'> | Use style attribute. | CSS |
function process(): void {{ return 98; }} | function process(): number {{ return 98; }} | Return type mismatch. | TypeScript |
<div><p>world</div></p> | <div><p>world</p></div> | Nest properly. | HTML |
<center>result</center> | <div style='text-align:center;'>result</div> | Use CSS. | HTML |
for (int i=0; i<14; i++) {{}} | for (int i=0; i<14; i++) {{}} | Correct. | Java |
if (val = 55) {{}} | if (val == 55) {{}} | Use ==. | Kotlin |
if ($y = 19) {{}} | if ($y -eq 19) {{}} | Use -eq. | PowerShell |
$list[93] = 5; | if (isset($list[93])) $list[93] = 5; | Check existence. | PHP |
["hello", 16] | ["hello", 16] | Correct. | JSON |
jwt.sign({{id:54}}, 'token'); | jwt.sign({{id:54}}, 'token', {{expiresIn:'2h'}}); | Add expiration. | Node.js |
yield z | yield z | Correct yield. | Python |
int[] values = new int[70];
values[70] = 5; | int[] values = new int[70];
if (70 < values.length) values[70] = 5; | Check bounds. | Java |
let foo: Int = 'world' | let foo: String = 'world' | Fix type. | Swift |
var x = 5; x = "hello" | var x = "hello" | Type mismatch. | Swift |
Write-Host 'value' | Write-Host 'value' | Correct. | PowerShell |
var x = 54; | var x = 54; | Correct. | Dart |
String name = 'message'; | String name = 'message'; | Correct. | Dart |
print 'world' | print 'world'; | Add semicolon. | Perl |
const num = 66; num = 2; | let num = 66; num = 2; | Cannot reassign const. | JavaScript |
let vec=vec![4,83,21]; let first=&vec[0]; vec.push(7); | let mut vec=vec![4,83,21]; let first=vec[0]; vec.push(7); | Copy instead of reference. | Rust |
h1 {{ font-size:50px color:red; }} | h1 {{ font-size:50px; color:red; }} | Add semicolon. | CSS |
let c: i32 = "info"; | let c: &str = "info"; | Type mismatch. | Rust |
$x = 5; echo $x | $x = 5; echo $x; | Missing semicolon. | PHP |
{{"id":"test",}} | {{"id":"test"}} | Remove trailing comma. | JSON |
for i=1,28 do print(i) end | for i=1,28 do print(i) end | Correct. | Lua |
[94, 55, 1 | [94, 55, 1] | Close bracket. | Python |
let mut num=99; let ref1=&mut num; let ref2=&mut num; | let mut num=99; {{ let ref1=&mut num; }} let ref2=&mut num; | Only one mutable borrow. | Rust |
{ "name": "world" } | { "name": "world" } | Correct. | JSON |
for (a in list) | for (a of list) | for...in iterates keys. | JavaScript |
const http = require('http'); http.createServer((req,res) => res.end('message')).listen(4); | const http = require('http'); http.createServer((req,res) => res.end('message')).listen(4); | Correct. | Node.js |
value: result
value: world, | value: result
value: world | Remove comma. | YAML |
.Person {{ color: #333; }} | .Person {{ color: #333; }} | Correct. | CSS |
my @arr = (26,53,60); | my @arr = (26,53,60); | Correct. | Perl |
if ($num = 36) | if ($num == 36) | Use ==. | Perl |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
function test(b:string){{return b;}} test(40); | function test(b:string){{return b;}} test('hello'); | Pass correct type. | TypeScript |
def handle():
print('output') | def handle():
print('output') | Indent function body. | Python |
const p:Person = {{name:'data'}}; | const p:Person = {{name:'data', age:50}}; | Add missing property. | TypeScript |
items[32] | if items.indices.contains(32) {{ items[32] }} | Check index. | Swift |
<br></br> | <br> | Self-closing. | HTML |
$data = 42; if ($data = 42) {{}} | $data = 42; if ($data == 42) {{}} | Use ==. | PHP |
if val = 64 then
print('test')
end | if val == 64 then
print('test')
end | Use ==. | Lua |
// comment | /* comment */ | Use /* */. | CSS |
class Item {{ int x; }}; | class Item {{ public: int x; }}; | Make public. | C++ |
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