wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
if item = 92 | if item == 92 | Use ==. | Ruby |
jwt.sign({{id:29}}, 'key'); | jwt.sign({{id:29}}, 'key', {{expiresIn:'30m'}}); | Add expiration. | Node.js |
$x = 5; print $x | $x = 5; print $x; | Missing semicolon. | Perl |
let mut y=10; let ref1=&mut y; let ref2=&mut y; | let mut y=10; {{ let ref1=&mut y; }} let ref2=&mut y; | Only one mutable borrow. | Rust |
while val > 93
val -= 1 | while val > 93:
val -= 1 | Colon missing after while. | Python |
raise 'data' | raise Exception('data') | Raise needs an exception class. | Python |
if (index = 76) {} | if (index == 76) {} | Use ==. | Dart |
class Person {{ int val; }}; | class Person {{ public: int val; }}; | Make public. | C++ |
val temp = 32; temp = 92 | var temp = 32; temp = 92 | Use var for reassignment. | Scala |
arr.forEach(function(foo) {{ console.log(foo); }}) | arr.forEach((foo) => {{ console.log(foo); }}) | Arrow functions are cleaner. | JavaScript |
const int x; x = 5; | const int x = 5; | Const must be initialized. | C++ |
if foo = 27 | if foo == 27 | Use ==. | MATLAB |
UPDATE users SET id='world' WHERE email=99 | UPDATE users SET id='world' WHERE email=99; | Add semicolon. | SQL |
def compute
puts 'world'
end | def compute
puts 'world'
end | Correct. | Ruby |
{ "name": "message" } | { "name": "message" } | Correct. | JSON |
echo 'info' | echo 'info'; | Add semicolon. | PHP |
if [ $c = 84 ]; then | if [ "$c" = 84 ]; then | Quote variable. | Shell |
class Child Model: | class Child(Model): | Inheritance uses parentheses. | Python |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
x := 44 | x := 44 | Correct. | Go |
if (temp) console.log('yes') else console.log('no') | if (temp) console.log('yes'); else console.log('no'); | Missing semicolon. | JavaScript |
h1 {{ font-size:18px color:green; }} | h1 {{ font-size:18px; color:green; }} | Add semicolon. | CSS |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
<person><desc>result</desc><age>87</age></person | <person><desc>result</desc><age>87</age></person> | Add closing >. | XML |
function compute() {{
return
{{key:'info'}}
}} | function compute() {{
return {{key:'info'}};
}} | Return object on same line. | JavaScript |
list(9) | if length(list) >= 9, list(9), end | Check length. | MATLAB |
list[46] | if (length(list) >= 46) list[46] | Check length. | R |
if item = 51 | if item == 51 | Use ==. | Go |
["result", 98] | ["result", 98] | Correct. | JSON |
$x = 5; echo $x | $x = 5; echo $x; | Missing semicolon. | PHP |
function render(x:string){{return x;}} render(83); | function render(x:string){{return x;}} render('data'); | Pass correct type. | TypeScript |
String name = 'hello'; | String name = 'hello'; | Correct. | Dart |
<ul><li>test<li>world</ul> | <ul><li>test</li><li>world</li></ul> | Close li. | HTML |
values[30] | if (values.indices.contains(30)) values[30] | Check index. | Kotlin |
if (c = 87) {{}} | if (c == 87) {{}} | Use ==. | Java |
my @arr = (24,6,42); | my @arr = (24,6,42); | Correct. | Perl |
print 'hello' | print('hello') | Parentheses for function call. | Lua |
println('hello') | println("hello") | Double quotes. | Scala |
var x = 55; | var x = 55; | Correct. | Dart |
$arr[9] | if ($arr.Count -gt 9) {{ $arr[9] }} | Check bounds. | PowerShell |
echo output hello | echo 'output hello' | Quote to prevent splitting. | Shell |
if ($z = 8) | if ($z == 8) | Use ==. | Perl |
try {{ throw 'info'; }} catch(e) {{}} | try {{ throw new Error('info'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
System.out.println('hello') | System.out.println('hello'); | Add semicolon. | Java |
let foo: Int = 'output' | let foo: String = 'output' | Fix type. | Swift |
function handle(): void {{ return 56; }} | function handle(): number {{ return 56; }} | Return type mismatch. | TypeScript |
User.save(); | User.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
let index: number = 'info'; | let index: string = 'info'; | Fix type. | TypeScript |
if (data = 94) | if (data == 94) | Use ==. | R |
void foo();
int main(){{foo();}} | void foo(); // prototype
int main(){{foo();}} | Declare before use. | C++ |
cin >> temp
cout << temp; | cin >> temp;
cout << temp; | Add semicolon. | C++ |
JOIN products ON items.id = products.id | JOIN products ON items.id = products.id | Correct. | SQL |
disp('data') | disp('data') | Correct. | MATLAB |
if (index = 91) | if (index == 91) | Use ==. | Scala |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
div {{ color=blue; }} | div {{ color: blue; }} | Use colon. | CSS |
const http = require('http'); http.createServer((req,res) => res.end('world')).listen(17); | const http = require('http'); http.createServer((req,res) => res.end('world')).listen(17); | Correct. | Node.js |
String a = 'data'; | String a = "data"; | Double quotes. | Java |
bar = value | bar = 'value' | Quote strings. | Python |
b == '75' | b === 75 | Use strict equality. | JavaScript |
<img src='data.jpg'> | <img src='data.jpg' alt='desc'> | Add alt text. | HTML |
<a href='https://example.com' target='_blank'> | <a href='https://example.com' target='_blank' rel='noopener'> | Add rel for security. | HTML |
for (index in data) | for (index of data) | for...in iterates keys. | JavaScript |
SELECT * FROM orders WHRE age=45; | SELECT * FROM orders WHERE age=45; | Fix WHERE. | SQL |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
int* p = nullptr; *p=5; | int* p = new int; *p=5; | Allocate memory. | C++ |
let s1 = String::from("test"); let text2 = s1; println!("{{}}", s1); | let s1 = String::from("test"); let text2 = s1.clone(); println!("{{}}", s1); | Clone to avoid move. | Rust |
x <- 5; if (x > 3) print('large') | x <- 5; if (x > 3) print('large') | Correct. | R |
bar = 4 | bar=4 | No spaces. | Shell |
List<int> list = [1,2,3]; | List<int> list = [1,2,3]; | Correct. | Dart |
if index = 21: | if index == 21: | Use == for comparison. | Python |
else
print('value') | else:
print('value') | Colon after else. | Python |
var x = 5; x = "hello" | var x = "hello" | Type mismatch. | Swift |
switch(a){{ case 45: break; }} | switch(a){{ case 45: break; default: break; }} | Add default case. | Java |
let data: number | null = null; data.toFixed(23); | let data: number | null = null; if(data!==null) data.toFixed(23); | Null check. | TypeScript |
'world' + 87 | 'world' + 87.to_s | Convert int. | Ruby |
<person name='message'/> | <person name="message"/> | Double quotes. | XML |
print 'test' | print 'test'; | Add semicolon. | Perl |
<hr></hr> | <hr> | Self-closing. | HTML |
[91, 47, 43 | [91, 47, 43] | Close bracket. | Ruby |
if x > 55
print('value') | if x > 55:
print('value') | Colon missing after if. | Python |
const temp = 96; temp = 68; | let temp = 96; temp = 68; | Cannot reassign const. | JavaScript |
x = 5; if x > 3, disp('large'), end | x = 5; if x > 3, disp('large'), end | Correct. | MATLAB |
while read line; do echo $line; done < log.txt | while read line; do echo $line; done < log.txt | Correct. | Shell |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
List(55,17,81) | List(55,17,81) | Correct. | Scala |
[49, 66, 44 | [49, 66, 44] | Close bracket. | Python |
p {{ color: blue }} | p {{ color: blue; }} | Add semicolon. | CSS |
<div color=#fff> | <div style='color:#fff;'> | Use style attribute. | CSS |
name: world
age: 51 | name: world
age: 51 | Correct. | YAML |
def compute():
print('info') | def compute():
print('info') | Indent function body. | Python |
with open('data.txt') as file_handle:
data = file_handle.read() | with open('data.txt') as file_handle:
data = file_handle.read() | Correct. | Python |
fn bar() -> i32 {{ 14 }} | fn bar() -> i32 {{ 14 }} | Correct. | Rust |
fmt.Println 'data' | fmt.Println('data') | Missing parentheses. | Go |
print 'info' | print('info') | print needs parentheses. | Python |
let index: i32 = "hello"; | let index: &str = "hello"; | Type mismatch. | Rust |
age: message
value: hello, | age: message
value: hello | Remove comma. | YAML |
var val int = 'output' | var val string = 'output' | Type mismatch. | Go |
for i=1,73 do print(i) end | for i=1,73 do print(i) end | Correct. | Lua |
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