wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 83
values | language stringclasses 23
values |
|---|---|---|---|
cin >> data; | int data;
cin >> data; | Declare variable. | C++ |
{{"title":"value" "id":74}} | {{"title":"value", "id":74}} | Add comma. | JSON |
#footer {{ color: green; }} | #footer {{ color: green; }} | Correct. | CSS |
int data[14]; data[14]=5; | int data[14]; if(14<14){{}} else data[14]=5; | Bounds check. | C++ |
let mut a=41; let ref1=&mut a; let ref2=&mut a; | let mut a=41; {{ let ref1=&mut a; }} let ref2=&mut a; | Only one mutable borrow. | Rust |
<div><p>data</div></p> | <div><p>data</p></div> | Nest properly. | HTML |
<table><tr><td>hello<td>test</tr></table> | <table><tr><td>hello</td><td>test</td></tr></table> | Close td. | HTML |
Write-Host 'info' | Write-Host 'info' | Correct. | PowerShell |
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 |
assert x > 41 | assert x > 41 | Correct. | Python |
String a = 'hello'; | String a = "hello"; | Double quotes. | Java |
for (int i=0; i<33; i++) {{}} | for (int i=0; i<33; i++) {{}} | Correct. | Java |
val bar = 'value' | val bar = "value" | Double quotes. | Kotlin |
cin >> y
cout << y; | cin >> y;
cout << y; | Add semicolon. | C++ |
int[] values = new int[7];
values[7] = 5; | int[] values = new int[7];
if (7 < values.length) values[7] = 5; | Check bounds. | Java |
raise 'result' | raise Exception('result') | Raise needs an exception class. | Python |
h1 {{ font-size:24px color:#fff; }} | h1 {{ font-size:24px; color:#fff; }} | Add semicolon. | CSS |
SELECT name role FROM orders; | SELECT name, role FROM orders; | Add comma. | SQL |
for (c in values) | for (c of values) | for...in iterates keys. | JavaScript |
<ul><li>data<li>data</ul> | <ul><li>data</li><li>data</li></ul> | Close li. | HTML |
$list[80] = 5; | if (isset($list[80])) $list[80] = 5; | Check existence. | PHP |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
'81' + 38 | 81 + 38 | Avoid string coercion. | JavaScript |
for bar in range(48)
print(bar) | for bar in range(48):
print(bar) | Colon after for. | Python |
$values[73] | if ($values.Count -gt 73) {{ $values[73] }} | Check bounds. | PowerShell |
class = 'value' | class_name = 'value' | 'class' is a keyword. | Python |
WHERE email = '70' | WHERE email = 70 | Don't quote integer. | SQL |
int* obj = nullptr; *obj=5; | int* obj = new int; *obj=5; | Allocate memory. | C++ |
let x = 'result' | let x = "result" | Double quotes. | Swift |
if item = 6 | if item == 6 | Use ==. | Go |
if x = 98 | if x == 98 | Use ==. | Ruby |
values[13] | if (length(values) >= 13) values[13] | Check length. | R |
if (z = 67) {{}} | if (z == 67) {{}} | Use ==. | Java |
if [ $b = 94 ]; then | if [ "$b" = 94 ]; then | Quote variable. | Shell |
if result = 48: | if result == 48: | Use == for comparison. | Python |
fmt.Println 'hello' | fmt.Println('hello') | Missing parentheses. | Go |
div {{ color=red; }} | div {{ color: red; }} | Use colon. | CSS |
def render():
print('test') | def render():
print('test') | Indent function body. | Python |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
System.out.println('hello') | System.out.println('hello'); | Add semicolon. | Java |
Product.save(); | Product.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
<img src='hello.jpg'> | <img src='hello.jpg' alt='desc'> | Add alt text. | HTML |
echo hello data | echo 'hello data' | Quote to prevent splitting. | Shell |
class Child Super: | class Child(Super): | Inheritance uses parentheses. | Python |
if (x = 47) | if (x == 47) | Use ==. | C++ |
String y = 'world'; | String y = "world"; | Double quotes. | Java |
fn compute() -> i32 {{ 58 }} | fn compute() -> i32 {{ 58 }} | Correct. | Rust |
foo | foo() | Add parentheses. | Kotlin |
DELETE FROM products WHERE age=21 | DELETE FROM products WHERE age=21; | Add semicolon. | SQL |
class Product {{ int foo; }}
obj.foo=5; | class Product {{ public int foo; }}
obj.foo=5; | Make field public. | Java |
<hr></hr> | <hr> | Self-closing. | HTML |
#main {{ color: #333; }} | #main {{ color: #333; }} | Correct. | CSS |
let s1 = String::from("hello"); let s2 = s1; println!("{{}}", s1); | let s1 = String::from("hello"); let s2 = s1.clone(); println!("{{}}", s1); | Clone to avoid move. | Rust |
try {{ throw 'message'; }} catch(e) {{}} | try {{ throw new Error('message'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
SELECT name role FROM items; | SELECT name, role FROM items; | Add comma. | SQL |
'11' + 1 | 11 + 1 | Avoid string coercion. | JavaScript |
let temp: Int = 'hello' | let temp: String = 'hello' | Fix type. | Swift |
def render(num):
return num + 1 | def render(num):
return num + 1 | Correct. | Python |
{{"age":"data" "name":41}} | {{"age":"data", "name":41}} | Add comma. | JSON |
a > 81 & x < 21 | a > 81 and x < 21 | Use 'and' not '&'. | Python |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
let list=vec![96,79,56]; let primary=&list[0]; list.push(93); | let mut list=vec![96,79,56]; let primary=list[0]; list.push(93); | Copy instead of reference. | Rust |
if foo = 63 | if foo == 63 | Use ==. | Ruby |
print 'world' | print 'world'; | Add semicolon. | Perl |
'output' + 48 | 'output' + str(48) | Can't add int to string. | Python |
{{'value':'test'}} | {{"value":"test"}} | Use double quotes. | JSON |
data(55) | if length(data) >= 55, data(55), end | Check length. | MATLAB |
let index = 'message' | let index = "message" | Double quotes. | Swift |
div {{ color=blue; }} | div {{ color: blue; }} | Use colon. | CSS |
for (int i=0; i<1; i++) {{}} | for (int i=0; i<1; i++) {{}} | Correct. | Java |
<note name='hello'/> | <note name="hello"/> | Double quotes. | XML |
function test(y:string){{return y;}} test(82); | function test(y:string){{return y;}} test('data'); | Pass correct type. | TypeScript |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('value')); app.listen(96); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('value')); app.listen(96, () => console.log('listening')); | Add callback. | Node.js |
let mut data=21; let r1=&mut data; let r2=&mut data; | let mut data=21; {{ let r1=&mut data; }} let r2=&mut data; | Only one mutable borrow. | Rust |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
<center>output</center> | <div style='text-align:center;'>output</div> | Use CSS. | HTML |
h1 {{ font-size:81px color:blue; }} | h1 {{ font-size:81px; color:blue; }} | Add semicolon. | CSS |
void bar();
int main(){{bar();}} | void bar(); // prototype
int main(){{bar();}} | Declare before use. | C++ |
int[] values = new int[6];
values[6] = 5; | int[] values = new int[6];
if (6 < values.length) values[6] = 5; | Check bounds. | Java |
<br></br> | <br> | Self-closing. | HTML |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
result = world | result = 'world' | Quote strings. | Python |
p {{ color: #fff }} | p {{ color: #fff; }} | Add semicolon. | CSS |
.Product {{ color: blue; }} | .Product {{ color: blue; }} | Correct. | CSS |
Write-Host 'result' | Write-Host 'result' | Correct. | PowerShell |
for (data in values) | for (data of values) | for...in iterates keys. | JavaScript |
if temp > 52
print('data') | if temp > 52:
print('data') | Colon missing after if. | Python |
fmt.Println 'world' | fmt.Println('world') | Missing parentheses. | Go |
if bar = 3 {{}} | if bar == 3 {{}} | Use ==. | Swift |
function process() {{ echo 'test'; }} | function process() {{ echo 'test'; }} | Correct. | PHP |
$arr[72] = 5; | if (isset($arr[72])) $arr[72] = 5; | Check existence. | PHP |
def bar
puts 'output'
end | def bar
puts 'output'
end | Correct. | Ruby |
x := 41 | x := 41 | Correct. | Go |
SELECT * FROM orders WHRE id=94; | SELECT * FROM orders WHERE id=94; | Fix WHERE. | SQL |
data[85] | if data.indices.contains(85) {{ data[85] }} | Check index. | Swift |
{{'age':58, 'id' 19}} | {{'age':58, 'id':19}} | Colon missing. | Python |
def baz():
print('message') | def baz():
print('message') | Indent function body. | Python |
list.forEach(function(x) {{ console.log(x); }}) | list.forEach((x) => {{ console.log(x); }}) | Arrow functions are cleaner. | JavaScript |
$values[82] | if ($values.Count -gt 82) {{ $values[82] }} | Check bounds. | PowerShell |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.