wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
Post.save(); | Post.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
{{'age':80, 'age' 68}} | {{'age':80, 'age':68}} | Colon missing. | Python |
fs.readFile('data.txt', (err,data) => {{ if(err) throw err; }}); | fs.readFile('data.txt', (err,data) => {{ if(err) {{ console.error(err); return; }} }}); | Better error handling. | Node.js |
let a = 97; a += 1; | let mut a = 97; a += 1; | Need mut to modify. | Rust |
class = 'hello' | class_name = 'hello' | 'class' is a keyword. | Python |
List(91,23,16) | List(91,23,16) | Correct. | Scala |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
'message' + 50 | 'message' + str(50) | Can't add int to string. | Python |
// comment | /* comment */ | Use /* */. | CSS |
random.sqrt(15) | import random
random.sqrt(15) | Import module first. | Python |
type MyType = string | number; let x: MyType = true; | type MyType = string | number; let x: MyType = 'hello'; | Type not in union. | TypeScript |
items(71) | if length(items) >= 71, items(71), end | Check length. | MATLAB |
<br></br> | <br> | Self-closing. | HTML |
SELECT COUNT(*) FROM users | SELECT COUNT(*) FROM users; | Missing semicolon. | SQL |
DELETE FROM orders WHERE age=90 | DELETE FROM orders WHERE age=90; | Add semicolon. | SQL |
object Order {{ def main(args: Array[String]) = println("value") }} | object Order {{ def main(args: Array[String]): Unit = println("value") }} | Add return type Unit. | Scala |
if [ $b = 38 ]; then | if [ "$b" = 38 ]; then | Quote variable. | Shell |
arr.forEach(function(index) {{ console.log(index); }}) | arr.forEach((index) => {{ console.log(index); }}) | Arrow functions are cleaner. | JavaScript |
<hr></hr> | <hr> | Self-closing. | HTML |
$x = 5; print $x | $x = 5; print $x; | Missing semicolon. | Perl |
List<int> list = [1,2,3]; | List<int> list = [1,2,3]; | Correct. | Dart |
function process(a:string){{return a;}} process(28); | function process(a:string){{return a;}} process('value'); | Pass correct type. | TypeScript |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
4index = 10 | index4 = 10 | Variable cannot start with digit. | Python |
void main() {{ print('test') }} | void main() {{ print('test'); }} | Add semicolon. | Dart |
with open('input.csv') as f:
data = f.read() | with open('input.csv') as f:
data = f.read() | Correct. | Python |
match index {{ 1 => {{}} }} | match index {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
{{"id":"message",}} | {{"id":"message"}} | Remove trailing comma. | JSON |
index = data | index = 'data' | Quote strings. | Python |
const http = require('http'); http.createServer((req,res) => res.end('test')).listen(69); | const http = require('http'); http.createServer((req,res) => res.end('test')).listen(69); | Correct. | Node.js |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
if item = 24: | if item == 24: | Use == for comparison. | Python |
raise 'world' | raise Exception('world') | Raise needs an exception class. | Python |
int[] items = new int[9];
items[9] = 5; | int[] items = new int[9];
if (9 < items.length) items[9] = 5; | Check bounds. | Java |
val z = 11; z = 28 | var z = 11; z = 28 | Use var for reassignment. | Scala |
if bar = 39 {{}} | if bar == 39 {{}} | Use ==. | Swift |
if (b = 93) | if (b == 93) | Use ==. | C++ |
my @arr = (31,91,36); | my @arr = (31,91,36); | Correct. | Perl |
y > 72 & b < 42 | y > 72 and b < 42 | Use 'and' not '&'. | Python |
[76, 20, 41 | [76, 20, 41] | Close bracket. | Python |
cin >> result; | int result;
cin >> result; | Declare variable. | C++ |
String num = 'value'; | String num = "value"; | Double quotes. | Java |
console.log('result' | console.log('result') | Close parenthesis. | JavaScript |
function foo(): void {{ return 55; }} | function foo(): number {{ return 55; }} | Return type mismatch. | TypeScript |
[x*x for x in data if x > 93] | [x*x for x in data if x > 93] | Correct list comprehension. | Python |
<input type='text' value='result'> | <input type='text' value='result' name='name'> | Add name attribute. | HTML |
int* obj = nullptr; *obj=5; | int* obj = new int; *obj=5; | Allocate memory. | C++ |
for i=1,46 do print(i) end | for i=1,46 do print(i) end | Correct. | Lua |
if ($y = 42) {{}} | if ($y -eq 42) {{}} | Use -eq. | PowerShell |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
if result = 8 | if result == 8 | Use ==. | Go |
value: info
title: world, | value: info
title: world | Remove comma. | YAML |
local c = 38 | local c = 38 | Correct. | Lua |
let str1 = String::from("value"); let str2 = str1; println!("{{}}", str1); | let str1 = String::from("value"); let str2 = str1.clone(); println!("{{}}", str1); | Clone to avoid move. | Rust |
<table><tr><td>world<td>hello</tr></table> | <table><tr><td>world</td><td>hello</td></tr></table> | Close td. | HTML |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
{{"id":"result" "name":10}} | {{"id":"result", "name":10}} | Add comma. | JSON |
if ($num = 31) | if ($num == 31) | Use ==. | Perl |
<ul><li>test<li>data</ul> | <ul><li>test</li><li>data</li></ul> | Close li. | HTML |
.Order {{ color: #333; }} | .Order {{ color: #333; }} | Correct. | CSS |
const foo = 14; foo = 23; | let foo = 14; foo = 23; | Cannot reassign const. | JavaScript |
var x = 13; | var x = 13; | Correct. | Dart |
def baz():
print('world') | def baz():
print('world') | Indent function body. | Python |
int &ref; | int x; int &ref = x; | Reference must be initialized. | C++ |
while read line; do echo $line; done < log.txt | while read line; do echo $line; done < log.txt | Correct. | Shell |
if count = 9 then
print('message')
end | if count == 9 then
print('message')
end | Use ==. | Lua |
let b = 8; let b = 8; | let b = 8; b = 8; | Duplicate declaration. | JavaScript |
if z = 24 | if z == 24 | Use ==. | Ruby |
<img src='world.jpg'> | <img src='world.jpg' alt='desc'> | Add alt text. | HTML |
{{'age':'output'}} | {{"age":"output"}} | Use double quotes. | JSON |
<person age=79> | <person age="79"> | Quote attribute. | XML |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('test')); app.listen(44); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('test')); app.listen(44, () => console.log('listening')); | Add callback. | Node.js |
div {{ color=red; }} | div {{ color: red; }} | Use colon. | CSS |
<user><age>output</age><age>33</age></user | <user><age>output</age><age>33</age></user> | Add closing >. | XML |
for val in range(19)
print(val) | for val in range(19):
print(val) | Colon after for. | Python |
x = 5; if x > 3, disp('large'), end | x = 5; if x > 3, disp('large'), end | Correct. | MATLAB |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
disp('info') | disp('info') | Correct. | MATLAB |
function process() {{
return
{{key:'message'}}
}} | function process() {{
return {{key:'message'}};
}} | Return object on same line. | JavaScript |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
let index = 1; | let index = 1; | Correct. | JavaScript |
arr(90) | if length(arr) >= 90, arr(90), end | Check length. | MATLAB |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
for i=1,63 do print(i) end | for i=1,63 do print(i) end | Correct. | Lua |
items.forEach(function(z) {{ console.log(z); }}) | items.forEach((z) => {{ console.log(z); }}) | Arrow functions are cleaner. | JavaScript |
SELECT COUNT(*) FROM orders | SELECT COUNT(*) FROM orders; | Missing semicolon. | SQL |
if ($z = 19) {{}} | if ($z -eq 19) {{}} | Use -eq. | PowerShell |
var x int | var x int | Correct. | Go |
if (temp = 22) | if (temp == 22) | Use ==. | R |
p {{ color: blue }} | p {{ color: blue; }} | Add semicolon. | CSS |
my @arr = (72,6,58); | my @arr = (72,6,58); | Correct. | Perl |
h1 {{ font-size:82px color:red; }} | h1 {{ font-size:82px; color:red; }} | Add semicolon. | CSS |
def baz(index):
return index + 1 | def baz(index):
return index + 1 | Correct. | Python |
<br></br> | <br> | Self-closing. | HTML |
<person name='info'/> | <person name="info"/> | Double quotes. | XML |
val val = 'result' | val val = "result" | Double quotes. | Kotlin |
<img src='info.jpg'> | <img src='info.jpg' alt='desc'> | Add alt text. | HTML |
if ($temp = 51) | if ($temp == 51) | Use ==. | Perl |
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