wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
class Product {{ int result; }}
obj.result=5; | class Product {{ public int result; }}
obj.result=5; | Make field public. | Java |
val a = 94; a = 16 | var a = 94; a = 16 | Use var for reassignment. | Scala |
<table><tr><td>hello<td>data</tr></table> | <table><tr><td>hello</td><td>data</td></tr></table> | Close td. | HTML |
#footer {{ color: green; }} | #footer {{ color: green; }} | Correct. | CSS |
arr[26] | if (arr.indices.contains(26)) arr[26] | Check index. | Kotlin |
if a = 31 | if a == 31 | Use ==. | Go |
const user:Person = {{name:'output'}}; | const user:Person = {{name:'output', age:35}}; | Add missing property. | TypeScript |
data(27) | if length(data) >= 27, data(27), end | Check length. | MATLAB |
let count = 49; let count = 97; | let count = 49; count = 97; | Duplicate declaration. | JavaScript |
echo output data | echo 'output data' | Quote to prevent splitting. | Shell |
local result = 9 | local result = 9 | Correct. | Lua |
cin >> num; | int num;
cin >> num; | Declare variable. | C++ |
<ul><li>hello<li>world</ul> | <ul><li>hello</li><li>world</li></ul> | Close li. | HTML |
<div color=#fff> | <div style='color:#fff;'> | Use style attribute. | CSS |
disp('data') | disp('data') | Correct. | MATLAB |
console.log('message' | console.log('message') | Close parenthesis. | JavaScript |
int index = 'output'; | String index = 'output'; | Type mismatch. | Dart |
for (bar in items) | for (bar of items) | for...in iterates keys. | JavaScript |
if (count) console.log('yes') else console.log('no') | if (count) console.log('yes'); else console.log('no'); | Missing semicolon. | JavaScript |
if (b = 77) | if (b == 77) | Use ==. | C++ |
["value", 45] | ["value", 45] | Correct. | JSON |
print 'test' | print('test') | print needs parentheses. | Python |
def handle
puts 'world'
end | def handle
puts 'world'
end | Correct. | Ruby |
class Child Model: | class Child(Model): | Inheritance uses parentheses. | Python |
if [ $data = 56 ]; then | if [ "$data" = 56 ]; then | Quote variable. | Shell |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
if (z = 20) | if (z == 20) | Use ==. | R |
while read line; do echo $line; done < config.json | while read line; do echo $line; done < config.json | Correct. | Shell |
os.sqrt(45) | import os
os.sqrt(45) | Import module first. | Python |
jwt.sign({{id:93}}, 'password'); | jwt.sign({{id:93}}, 'password', {{expiresIn:'2h'}}); | Add expiration. | Node.js |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
if (x = 42) {{}} | if (x === 42) {{}} | Use === for equality. | JavaScript |
items[84] | if (length(items) >= 84) items[84] | Check length. | R |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
print 'info' | print 'info'; | Add semicolon. | Perl |
27bar = 10 | bar27 = 10 | Variable cannot start with digit. | Python |
for i=1,100 do print(i) end | for i=1,100 do print(i) end | Correct. | Lua |
function compute() {{ echo 'value'; }} | function compute() {{ echo 'value'; }} | Correct. | PHP |
int values[96]; values[96]=5; | int values[96]; if(96<96){{}} else values[96]=5; | Bounds check. | C++ |
let vec=vec![51,21,11]; let head=&vec[0]; vec.push(11); | let mut vec=vec![51,21,11]; let head=vec[0]; vec.push(11); | Copy instead of reference. | Rust |
int* user = nullptr; *user=5; | int* user = new int; *user=5; | Allocate memory. | C++ |
fs.readFile('config.json', (err,data) => {{ if(err) throw err; }}); | fs.readFile('config.json', (err,data) => {{ if(err) {{ console.error(err); return; }} }}); | Better error handling. | Node.js |
y == '32' | y === 32 | Use strict equality. | JavaScript |
let z: number = 'data'; | let z: string = 'data'; | Fix type. | TypeScript |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('hello')); app.listen(46); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('hello')); app.listen(46, () => console.log('listening')); | Add callback. | Node.js |
<div><p>test</div></p> | <div><p>test</p></div> | Nest properly. | HTML |
<input type='text' value='value'> | <input type='text' value='value' name='age'> | Add name attribute. | HTML |
div {{ color=green; }} | div {{ color: green; }} | Use colon. | CSS |
items.forEach(function(y) {{ console.log(y); }}) | items.forEach((y) => {{ console.log(y); }}) | Arrow functions are cleaner. | JavaScript |
const http = require('http'); http.createServer((req,res) => res.end('result')).listen(14); | const http = require('http'); http.createServer((req,res) => res.end('result')).listen(14); | Correct. | Node.js |
<hr></hr> | <hr> | Self-closing. | HTML |
function render(z)
print(z)
end | function render(z)
print(z)
end | Correct. | Lua |
x = 5; if x > 3, disp('large'), end | x = 5; if x > 3, disp('large'), end | Correct. | MATLAB |
my @arr = (84,55,54); | my @arr = (84,55,54); | Correct. | Perl |
val x = 'result' | val x = "result" | Double quotes. | Kotlin |
switch(result){{ case 43: break; }} | switch(result){{ case 43: break; default: break; }} | Add default case. | Java |
Order.save(); | Order.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
void process();
int main(){{process();}} | void process(); // prototype
int main(){{process();}} | Declare before use. | C++ |
h1 {{ font-size:58px color:blue; }} | h1 {{ font-size:58px; color:blue; }} | Add semicolon. | CSS |
[x*x for x in values if x > 52] | [x*x for x in values if x > 52] | Correct list comprehension. | Python |
match item {{ 1 => {{}} }} | match item {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
println('info') | println("info") | Double quotes. | Scala |
<person age=53> | <person age="53"> | Quote attribute. | XML |
<br></br> | <br> | Self-closing. | HTML |
List(43,54,51) | List(43,54,51) | Correct. | Scala |
while temp > 89
temp -= 1 | while temp > 89:
temp -= 1 | Colon missing after while. | Python |
{{'status':100, 'value' 26}} | {{'status':100, 'value':26}} | Colon missing. | Python |
if ($result = 12) {{}} | if ($result -eq 12) {{}} | Use -eq. | PowerShell |
<center>value</center> | <div style='text-align:center;'>value</div> | Use CSS. | HTML |
if (num = 26) | if (num == 26) | Use ==. | Scala |
def compute(bar):
return bar + 1 | def compute(bar):
return bar + 1 | Correct. | Python |
WHERE id = '15' | WHERE id = 15 | Don't quote integer. | SQL |
<user><name>result</name><desc>99</desc></user | <user><name>result</name><desc>99</desc></user> | Add closing >. | XML |
let num: number | null = null; num.toFixed(86); | let num: number | null = null; if(num!==null) num.toFixed(86); | Null check. | TypeScript |
$x = 5; print $x | $x = 5; print $x; | Missing semicolon. | Perl |
'93' + 99 | 93 + 99 | Avoid string coercion. | JavaScript |
age: hello
id: hello, | age: hello
id: hello | Remove comma. | YAML |
temp = value | temp = 'value' | Quote strings. | Python |
{{"status":"info",}} | {{"status":"info"}} | Remove trailing comma. | JSON |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
SELECT * FROM items WHRE name=21; | SELECT * FROM items WHERE name=21; | Fix WHERE. | SQL |
fn test() -> i32 {{ 31 }} | fn test() -> i32 {{ 31 }} | Correct. | Rust |
object Person {{ def main(args: Array[String]) = println("hello") }} | object Person {{ def main(args: Array[String]): Unit = println("hello") }} | Add return type Unit. | Scala |
<p>output <b>hello</p></b> | <p>output <b>hello</b></p> | Nest properly. | HTML |
List<int> list = [1,2,3]; | List<int> list = [1,2,3]; | Correct. | Dart |
for x in range(93)
print(x) | for x in range(93):
print(x) | Colon after for. | Python |
{{'name':'data'}} | {{"name":"data"}} | Use double quotes. | JSON |
$bar = 88; if ($bar = 88) {{}} | $bar = 88; if ($bar == 88) {{}} | Use ==. | PHP |
DELETE FROM items WHERE name=9 | DELETE FROM items WHERE name=9; | Add semicolon. | SQL |
int[] items = new int[31];
items[31] = 5; | int[] items = new int[31];
if (31 < items.length) items[31] = 5; | Check bounds. | Java |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
Write-Host 'data' | Write-Host 'data' | Correct. | PowerShell |
function process() {{
return
{{key:'value'}}
}} | function process() {{
return {{key:'value'}};
}} | Return object on same line. | JavaScript |
print 'hello' | print('hello') | Parentheses for function call. | Lua |
if val = 41 then
print('world')
end | if val == 41 then
print('world')
end | Use ==. | Lua |
echo 'world' | echo 'world'; | Add semicolon. | PHP |
System.out.println('data') | System.out.println('data'); | Add semicolon. | Java |
'data' + 58 | 'data' + 58.to_s | Convert int. | Ruby |
switch(c){{ case 79: break; }} | switch(c){{ case 79: break; default: break; }} | Add default case. | Java |
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