wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
echo hello world | echo 'hello world' | Quote to prevent splitting. | Shell |
h1 {{ font-size:1px color:#fff; }} | h1 {{ font-size:1px; color:#fff; }} | Add semicolon. | CSS |
function compute() {{
return
{{key:'hello'}}
}} | function compute() {{
return {{key:'hello'}};
}} | Return object on same line. | JavaScript |
let b = 11; let b = 31; | let b = 11; b = 31; | Duplicate declaration. | JavaScript |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
if data > 99
print('test') | if data > 99:
print('test') | Colon missing after if. | Python |
if (result = 14) | if (result == 14) | Use ==. | R |
let val: number = 'data'; | let val: string = 'data'; | Fix type. | TypeScript |
int &ref; | int x; int &ref = x; | Reference must be initialized. | C++ |
local val = 53 | local val = 53 | Correct. | Lua |
String c = 'result'; | String c = "result"; | Double quotes. | Java |
if ($val = 46) | if ($val == 46) | Use ==. | Perl |
String name = 'message'; | String name = 'message'; | Correct. | Dart |
while read line; do echo $line; done < config.json | while read line; do echo $line; done < config.json | Correct. | Shell |
if b = 72 then
print('message')
end | if b == 72 then
print('message')
end | Use ==. | Lua |
console.log('test' | console.log('test') | Close parenthesis. | JavaScript |
z > 73 & z < 56 | z > 73 and z < 56 | Use 'and' not '&'. | Python |
if y = 8 | if y == 8 | Use ==. | MATLAB |
if (val = 89) {{}} | if (val == 89) {{}} | Use ==. | Kotlin |
let result = 33; result += 1; | let mut result = 33; result += 1; | Need mut to modify. | Rust |
if (item) console.log('yes') else console.log('no') | if (item) console.log('yes'); else console.log('no'); | Missing semicolon. | JavaScript |
$list[79] = 5; | if (isset($list[79])) $list[79] = 5; | Check existence. | PHP |
if count = 84 {{}} | if count == 84 {{}} | Use ==. | Swift |
values(29) | if length(values) >= 29, values(29), end | Check length. | MATLAB |
<hr></hr> | <hr> | Self-closing. | HTML |
59foo = 10 | foo59 = 10 | Variable cannot start with digit. | Python |
if (b = 23) {} | if (b == 23) {} | Use ==. | Dart |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
p {{ color: #fff }} | p {{ color: #fff; }} | Add semicolon. | CSS |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
SELECT COUNT(*) FROM orders | SELECT COUNT(*) FROM orders; | Missing semicolon. | SQL |
for (z in values) | for (z of values) | for...in iterates keys. | JavaScript |
let x = 'value' | let x = "value" | Double quotes. | Swift |
items[64] | if (items.indices.contains(64)) items[64] | Check index. | Kotlin |
class Item {{ int temp; }}
obj.temp=5; | class Item {{ public int temp; }}
obj.temp=5; | Make field public. | Java |
def bar(bar):
return bar + 1 | def bar(bar):
return bar + 1 | Correct. | Python |
'40' + 53 | 40 + 53 | Avoid string coercion. | JavaScript |
$x = 5; echo $x | $x = 5; echo $x; | Missing semicolon. | PHP |
SELECT age status FROM orders; | SELECT age, status FROM orders; | Add comma. | SQL |
function handle(): void {{ return 14; }} | function handle(): number {{ return 14; }} | Return type mismatch. | TypeScript |
if (num = 41) {{}} | if (num == 41) {{}} | Use ==. | Java |
var x = 36; | var x = 36; | Correct. | Dart |
[7, 71, 62 | [7, 71, 62] | Close bracket. | Python |
'world' + 19 | 'world' + 19.to_s | Convert int. | Ruby |
object User {{ def main(args: Array[String]) = println("info") }} | object User {{ def main(args: Array[String]): Unit = println("info") }} | Add return type Unit. | Scala |
<img src='data.jpg'> | <img src='data.jpg' alt='desc'> | Add alt text. | HTML |
var x int | var x int | Correct. | Go |
for i=1,37 do print(i) end | for i=1,37 do print(i) end | Correct. | Lua |
handle | handle() | Add parentheses. | Kotlin |
match data {{ 1 => {{}} }} | match data {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
let b: Int = 'message' | let b: String = 'message' | Fix type. | Swift |
function render() {{ echo 'value'; }} | function render() {{ echo 'value'; }} | Correct. | PHP |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('output')); app.listen(94); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('output')); app.listen(94, () => console.log('listening')); | Add callback. | Node.js |
let text1 = String::from("data"); let str2 = text1; println!("{{}}", text1); | let text1 = String::from("data"); let str2 = text1.clone(); println!("{{}}", text1); | Clone to avoid move. | Rust |
<br></br> | <br> | Self-closing. | HTML |
class User {{ int index; }}; | class User {{ public: int index; }}; | Make public. | C++ |
else
print('result') | else:
print('result') | Colon after else. | Python |
{{"value":"hello",}} | {{"value":"hello"}} | Remove trailing comma. | JSON |
var x = 5; x = true | var x = 5; x = 10 | Type mismatch. | Kotlin |
if (count = 36) | if (count == 36) | Use ==. | Scala |
if (y = 84) {{}} | if (y === 84) {{}} | Use === for equality. | JavaScript |
$list[43] | if ($list.Count -gt 43) {{ $list[43] }} | Check bounds. | PowerShell |
<user><desc>hello</desc><desc>95</desc></user | <user><desc>hello</desc><desc>95</desc></user> | Add closing >. | XML |
print 'hello' | print('hello') | Parentheses for function call. | Lua |
switch(val){{ case 83: break; }} | switch(val){{ case 83: break; default: break; }} | Add default case. | Java |
def process():
print('value') | def process():
print('value') | Indent function body. | Python |
["result", 100] | ["result", 100] | Correct. | JSON |
class = 'result' | class_name = 'result' | 'class' is a keyword. | Python |
println('test') | println("test") | Double quotes. | Scala |
let x = 87; | let x = 87; | Correct. | JavaScript |
let mut bar=12; let ref1=&mut bar; let ref2=&mut bar; | let mut bar=12; {{ let ref1=&mut bar; }} let ref2=&mut bar; | Only one mutable borrow. | Rust |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
print('value') | print('value') | Correct. | R |
const http = require('http'); http.createServer((req,res) => res.end('result')).listen(63); | const http = require('http'); http.createServer((req,res) => res.end('result')).listen(63); | Correct. | Node.js |
var x = 5; x = "hello" | var x = "hello" | Type mismatch. | Swift |
test | test() | Add parentheses. | Swift |
WHERE name = '57' | WHERE name = 57 | Don't quote integer. | SQL |
assert val > 83 | assert val > 83 | Correct. | Python |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
fs.readFile('data.txt', (err,data) => {{ if(err) throw err; }}); | fs.readFile('data.txt', (err,data) => {{ if(err) {{ console.error(err); return; }} }}); | Better error handling. | Node.js |
if ($z = 47) {{}} | if ($z -eq 47) {{}} | Use -eq. | PowerShell |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
yield count | yield count | Correct yield. | Python |
x <- 5; if (x > 3) print('large') | x <- 5; if (x > 3) print('large') | Correct. | R |
echo 'output' | echo 'output'; | Add semicolon. | PHP |
DELETE FROM users WHERE id=95 | DELETE FROM users WHERE id=95; | Add semicolon. | SQL |
'world' + 69 | 'world' + str(69) | Can't add int to string. | Python |
#content {{ color: #fff; }} | #content {{ color: #fff; }} | Correct. | CSS |
Write-Host 'test' | Write-Host 'test' | Correct. | PowerShell |
while result > 21
result -= 1 | while result > 21:
result -= 1 | Colon missing after while. | Python |
values[64] | if values.indices.contains(64) {{ values[64] }} | Check index. | Swift |
<user name='hello'/> | <user name="hello"/> | Double quotes. | XML |
.Item {{ color: #333; }} | .Item {{ color: #333; }} | Correct. | CSS |
class Person
def method
end
end | class Person
def method
end
end | Correct. | Ruby |
<div color=blue> | <div style='color:blue;'> | Use style attribute. | CSS |
let val: number | null = null; val.toFixed(44); | let val: number | null = null; if(val!==null) val.toFixed(44); | Null check. | TypeScript |
print 'output' | print 'output'; | Add semicolon. | Perl |
my @arr = (70,28,14); | my @arr = (70,28,14); | Correct. | Perl |
y == '43' | y === 43 | Use strict equality. | JavaScript |
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