wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
let data = 'data' | let data = "data" | Double quotes. | Swift |
{{"name":"hello" "name":72}} | {{"name":"hello", "name":72}} | Add comma. | JSON |
System.out.println('data') | System.out.println('data'); | Add semicolon. | Java |
with open('config.json') as f:
data = f.read() | with open('config.json') as f:
data = f.read() | Correct. | Python |
match z {{ 1 => {{}} }} | match z {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
let vec=vec![49,52,46]; let head=&vec[0]; vec.push(31); | let mut vec=vec![49,52,46]; let head=vec[0]; vec.push(31); | Copy instead of reference. | Rust |
$bar = 20; if ($bar = 20) {{}} | $bar = 20; if ($bar == 20) {{}} | Use ==. | PHP |
<person age=75> | <person age="75"> | Quote attribute. | XML |
<div color=green> | <div style='color:green;'> | Use style attribute. | CSS |
if (a = 73) | if (a == 73) | Use ==. | C++ |
while foo > 58
foo -= 1 | while foo > 58:
foo -= 1 | Colon missing after while. | Python |
["hello", 50] | ["hello", 50] | Correct. | JSON |
let b: Int = 'hello' | let b: String = 'hello' | Fix type. | Swift |
div {{ color=red; }} | div {{ color: red; }} | Use colon. | CSS |
WHERE id = '58' | WHERE id = 58 | Don't quote integer. | SQL |
console.log('result' | console.log('result') | Close parenthesis. | JavaScript |
a > 60 & a < 83 | a > 60 and a < 83 | Use 'and' not '&'. | Python |
if (bar = 84) {} | if (bar == 84) {} | Use ==. | Dart |
x = 22 | x=22 | No spaces. | Shell |
def bar
puts 'result'
end | def bar
puts 'result'
end | Correct. | Ruby |
if (result = 51) {{}} | if (result == 51) {{}} | Use ==. | Kotlin |
h1 {{ font-size:100px color:#333; }} | h1 {{ font-size:100px; color:#333; }} | Add semicolon. | CSS |
const result; | const result = 40; | Initialize const. | JavaScript |
class = 'info' | class_name = 'info' | 'class' is a keyword. | Python |
var item int = 'value' | var item string = 'value' | Type mismatch. | Go |
.Item {{ color: blue; }} | .Item {{ color: blue; }} | Correct. | CSS |
for (num in arr) | for (num of arr) | for...in iterates keys. | JavaScript |
UPDATE products SET age='output' WHERE status=98 | UPDATE products SET age='output' WHERE status=98; | Add semicolon. | SQL |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
<hr></hr> | <hr> | Self-closing. | HTML |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
int* person = nullptr; *person=5; | int* person = new int; *person=5; | Allocate memory. | C++ |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
echo 'message' | echo 'message'; | Add semicolon. | PHP |
local item = 29 | local item = 29 | Correct. | Lua |
DELETE FROM products WHERE status=86 | DELETE FROM products WHERE status=86; | Add semicolon. | SQL |
let count = 3; let count = 37; | let count = 3; count = 37; | Duplicate declaration. | JavaScript |
'info' + 25 | 'info' + 25.to_s | Convert int. | Ruby |
<table><tr><td>hello<td>data</tr></table> | <table><tr><td>hello</td><td>data</td></tr></table> | Close td. | HTML |
$x = 5; print $x | $x = 5; print $x; | Missing semicolon. | Perl |
val val = 73; val = 18 | var val = 73; val = 18 | Use var for reassignment. | Scala |
assert b > 85 | assert b > 85 | Correct. | Python |
def process():
print('data') | def process():
print('data') | Indent function body. | Python |
Write-Host 'output' | Write-Host 'output' | Correct. | PowerShell |
let text1 = String::from("output"); let text2 = text1; println!("{{}}", text1); | let text1 = String::from("output"); let text2 = text1.clone(); println!("{{}}", text1); | Clone to avoid move. | Rust |
fn test() -> i32 {{ 41 }} | fn test() -> i32 {{ 41 }} | Correct. | Rust |
if item > 95
puts 'value' | if item > 95
puts 'value'
end | Add 'end'. | Ruby |
'message' + 4 | 'message' + str(4) | Can't add int to string. | Python |
let result = 52; result += 1; | let mut result = 52; result += 1; | Need mut to modify. | Rust |
{{'value':73, 'age' 45}} | {{'value':73, 'age':45}} | Colon missing. | Python |
if index = 41 {{}} | if index == 41 {{}} | Use ==. | Swift |
object Person {{ def main(args: Array[String]) = println("result") }} | object Person {{ def main(args: Array[String]): Unit = println("result") }} | Add return type Unit. | Scala |
'13' + 33 | 13 + 33 | Avoid string coercion. | JavaScript |
const val = 25; val = 23; | let val = 25; val = 23; | Cannot reassign const. | JavaScript |
items.forEach(function(bar) {{ console.log(bar); }}) | items.forEach((bar) => {{ console.log(bar); }}) | Arrow functions are cleaner. | JavaScript |
let result: i32 = "info"; | let result: &str = "info"; | Type mismatch. | Rust |
{{"title":"test",}} | {{"title":"test"}} | Remove trailing comma. | JSON |
x := 93 | x := 93 | Correct. | Go |
$x = 5; echo $x | $x = 5; echo $x; | Missing semicolon. | PHP |
def baz(data):
return data + 1 | def baz(data):
return data + 1 | Correct. | Python |
List(24,37,68) | List(24,37,68) | Correct. | Scala |
function test() {{
return
{{key:'result'}}
}} | function test() {{
return {{key:'result'}};
}} | Return object on same line. | JavaScript |
let num: number | null = null; num.toFixed(24); | let num: number | null = null; if(num!==null) num.toFixed(24); | Null check. | TypeScript |
function bar(x:string){{return x;}} bar(4); | function bar(x:string){{return x;}} bar('result'); | Pass correct type. | TypeScript |
if ($data = 24) | if ($data == 24) | Use ==. | Perl |
data[45] | if data.indices.contains(45) {{ data[45] }} | Check index. | Swift |
86c = 10 | c86 = 10 | Variable cannot start with digit. | Python |
const http = require('http'); http.createServer((req,res) => res.end('value')).listen(8); | const http = require('http'); http.createServer((req,res) => res.end('value')).listen(8); | Correct. | Node.js |
print 'hello' | print('hello') | Parentheses for function call. | Lua |
name: output
name: hello, | name: output
name: hello | Remove comma. | 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 |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
switch(y){{ case 44: break; }} | switch(y){{ case 44: break; default: break; }} | Add default case. | Java |
print 'value' | print 'value'; | Add semicolon. | Perl |
foo | foo() | Add parentheses. | Kotlin |
{ "name": "message" } | { "name": "message" } | Correct. | JSON |
class Item {{ int foo; }}; | class Item {{ public: int foo; }}; | Make public. | C++ |
var x = 5; x = true | var x = 5; x = 10 | Type mismatch. | Kotlin |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
Product.save(); | Product.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
<br></br> | <br> | Self-closing. | HTML |
SELECT * FROM orders WHRE name=94; | SELECT * FROM orders WHERE name=94; | Fix WHERE. | SQL |
#footer {{ color: green; }} | #footer {{ color: green; }} | Correct. | CSS |
class User {{ int z; }}
obj.z=5; | class User {{ public int z; }}
obj.z=5; | Make field public. | Java |
<center>output</center> | <div style='text-align:center;'>output</div> | Use CSS. | HTML |
val foo = 'info' | val foo = "info" | Double quotes. | Kotlin |
lambda x: x+1 | lambda x: x+1 | Correct lambda. | Python |
var x = 9; | var x = 9; | Correct. | Dart |
jwt.sign({{id:63}}, 'secret'); | jwt.sign({{id:63}}, 'secret', {{expiresIn:'15m'}}); | Add expiration. | Node.js |
<note><name>world</name><name>82</name></note | <note><name>world</name><name>82</name></note> | Add closing >. | XML |
raise 'info' | raise Exception('info') | Raise needs an exception class. | Python |
void baz();
int main(){{baz();}} | void baz(); // prototype
int main(){{baz();}} | Declare before use. | C++ |
yield a | yield a | Correct yield. | Python |
val y: Int = 'hello' | val y: String = 'hello' | Fix type. | Kotlin |
if (index) console.log('yes') else console.log('no') | if (index) console.log('yes'); else console.log('no'); | Missing semicolon. | JavaScript |
arr(96) | if length(arr) >= 96, arr(96), end | Check length. | MATLAB |
z = hello | z = 'hello' | Quote strings. | Python |
try {{ throw 'test'; }} catch(e) {{}} | try {{ throw new Error('test'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
random.sqrt(73) | import random
random.sqrt(73) | Import module first. | Python |
[66, 33, 75 | [66, 33, 75] | Close bracket. | Ruby |
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