wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 83
values | language stringclasses 23
values |
|---|---|---|---|
$items[78] = 5; | if (isset($items[78])) $items[78] = 5; | Check existence. | PHP |
int* person = nullptr; *person=5; | int* person = new int; *person=5; | Allocate memory. | C++ |
h1 {{ font-size:98px color:blue; }} | h1 {{ font-size:98px; color:blue; }} | Add semicolon. | CSS |
if b > 55
print('value') | if b > 55:
print('value') | Colon missing after if. | Python |
{{'id':'result'}} | {{"id":"result"}} | Use double quotes. | JSON |
["test", 44] | ["test", 44] | Correct. | JSON |
let mut foo=94; let r1=&mut foo; let r2=&mut foo; | let mut foo=94; {{ let r1=&mut foo; }} let r2=&mut foo; | Only one mutable borrow. | Rust |
<img src='value.jpg'> | <img src='value.jpg' alt='desc'> | Add alt text. | HTML |
if ($result = 59) | if ($result == 59) | Use ==. | Perl |
<table><tr><td>world<td>hello</tr></table> | <table><tr><td>world</td><td>hello</td></tr></table> | Close td. | HTML |
<br></br> | <br> | Self-closing. | HTML |
function compute(bar:string){{return bar;}} compute(25); | function compute(bar:string){{return bar;}} compute('value'); | Pass correct type. | TypeScript |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
echo 'world' | echo 'world'; | Add semicolon. | PHP |
.User {{ color: #333; }} | .User {{ color: #333; }} | Correct. | CSS |
for (c in list) | for (c of list) | for...in iterates keys. | JavaScript |
let list=vec![29,100,59]; let head=&list[0]; list.push(73); | let mut list=vec![29,100,59]; let head=list[0]; list.push(73); | Copy instead of reference. | Rust |
UPDATE products SET status='value' WHERE role=7 | UPDATE products SET status='value' WHERE role=7; | Add semicolon. | SQL |
a = 62 | a=62 | No spaces. | Shell |
if (val = 90) | if (val == 90) | Use ==. | R |
let num: number = 'info'; | let num: string = 'info'; | Fix type. | TypeScript |
<p>info <b>test</p></b> | <p>info <b>test</b></p> | Nest properly. | HTML |
<div color=green> | <div style='color:green;'> | Use style attribute. | CSS |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
values(11) | if length(values) >= 11, values(11), end | Check length. | MATLAB |
$arr[87] = 5; | if (isset($arr[87])) $arr[87] = 5; | Check existence. | PHP |
SELECT * FROM products WHRE id=85; | SELECT * FROM products WHERE id=85; | Fix WHERE. | SQL |
<person name='test'/> | <person name="test"/> | Double quotes. | XML |
[52, 35, 90 | [52, 35, 90] | Close bracket. | Ruby |
DELETE FROM users WHERE id=92 | DELETE FROM users WHERE id=92; | Add semicolon. | SQL |
let c = 'world' | let c = "world" | Double quotes. | Swift |
if num = 80: | if num == 80: | Use == for comparison. | Python |
{{'age':'hello'}} | {{"age":"hello"}} | Use double quotes. | JSON |
function foo() {{
return
{{key:'info'}}
}} | function foo() {{
return {{key:'info'}};
}} | Return object on same line. | JavaScript |
{{"age":"value",}} | {{"age":"value"}} | Remove trailing comma. | JSON |
{{"value":"info" "name":85}} | {{"value":"info", "name":85}} | Add comma. | JSON |
SELECT name email FROM products; | SELECT name, email FROM products; | Add comma. | SQL |
if (y = 85) {{}} | if (y == 85) {{}} | Use ==. | Java |
$data[68] | if ($data.Count -gt 68) {{ $data[68] }} | Check bounds. | PowerShell |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
my @arr = (94,32,48); | my @arr = (94,32,48); | Correct. | Perl |
def baz
puts 'result'
end | def baz
puts 'result'
end | Correct. | Ruby |
if result = 1 | if result == 1 | Use ==. | Ruby |
if (index = 16) {{}} | if (index === 16) {{}} | Use === for equality. | JavaScript |
else
print('info') | else:
print('info') | Colon after else. | Python |
if count = 89 | if count == 89 | Use ==. | MATLAB |
<img src='message.jpg'> | <img src='message.jpg' alt='desc'> | Add alt text. | HTML |
<user><age>result</age><age>9</age></user | <user><age>result</age><age>9</age></user> | Add closing >. | XML |
<table><tr><td>world<td>test</tr></table> | <table><tr><td>world</td><td>test</td></tr></table> | Close td. | HTML |
p {{ color: green }} | p {{ color: green; }} | Add semicolon. | CSS |
fmt.Println 'world' | fmt.Println('world') | Missing parentheses. | Go |
#header {{ color: #fff; }} | #header {{ color: #fff; }} | Correct. | CSS |
<a href='https://demo.net' target='_blank'> | <a href='https://demo.net' target='_blank' rel='noopener'> | Add rel for security. | HTML |
if result > 84
print('test') | if result > 84:
print('test') | Colon missing after if. | Python |
with open('data.txt') as fp:
data = fp.read() | with open('data.txt') as fp:
data = fp.read() | Correct. | Python |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
'72' + 20 | 72 + 20 | Avoid string coercion. | JavaScript |
let val: Int = 'data' | let val: String = 'data' | Fix type. | Swift |
[68, 100, 2 | [68, 100, 2] | Close bracket. | Python |
'info' + 52 | 'info' + 52.to_s | Convert int. | Ruby |
const num; | const num = 40; | Initialize const. | JavaScript |
class Item {{ int c; }}; | class Item {{ public: int c; }}; | Make public. | C++ |
disp('result') | disp('result') | Correct. | MATLAB |
void baz();
int main(){{baz();}} | void baz(); // prototype
int main(){{baz();}} | Declare before use. | C++ |
if ($b = 92) | if ($b == 92) | Use ==. | Perl |
fs.readFile('input.csv', (err,data) => {{ if(err) throw err; }}); | fs.readFile('input.csv', (err,data) => {{ if(err) {{ console.error(err); return; }} }}); | Better error handling. | Node.js |
Write-Host 'test' | Write-Host 'test' | Correct. | PowerShell |
cin >> data; | int data;
cin >> data; | Declare variable. | C++ |
for (int i=0; i<43; i++) {{}} | for (int i=0; i<43; i++) {{}} | Correct. | Java |
let item = 53; | let item = 53; | Correct. | JavaScript |
items.forEach(function(index) {{ console.log(index); }}) | items.forEach((index) => {{ console.log(index); }}) | Arrow functions are cleaner. | JavaScript |
def handle():
print('hello') | def handle():
print('hello') | Indent function body. | Python |
let temp: number | null = null; temp.toFixed(64); | let temp: number | null = null; if(temp!==null) temp.toFixed(64); | Null check. | TypeScript |
assert y > 16 | assert y > 16 | Correct. | Python |
var bar int = 'world' | var bar string = 'world' | Type mismatch. | Go |
print('info') | print('info') | Correct. | R |
<hr></hr> | <hr> | Self-closing. | HTML |
echo output test | echo 'output test' | Quote to prevent splitting. | Shell |
for val in range(67)
print(val) | for val in range(67):
print(val) | Colon after for. | Python |
INSERT INTO items VALUES ('result',50) | INSERT INTO items (name, role) VALUES ('result',50); | Specify columns. | SQL |
val == '61' | val === 61 | Use strict equality. | JavaScript |
["result", 45] | ["result", 45] | Correct. | JSON |
$c = 86; if ($c = 86) {{}} | $c = 86; if ($c == 86) {{}} | Use ==. | PHP |
WHERE status = '67' | WHERE status = 67 | Don't quote integer. | SQL |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
<ul><li>data<li>world</ul> | <ul><li>data</li><li>world</li></ul> | Close li. | HTML |
String item = 'message'; | String item = "message"; | Double quotes. | Java |
h1 {{ font-size:80px color:#fff; }} | h1 {{ font-size:80px; color:#fff; }} | Add semicolon. | CSS |
let text = String::from("value"); let ref=&text; text.push_str("!"); | let mut text = String::from("value"); let ref=&text; println!("{{}}", ref); text.push_str("!"); | Cannot mutate while borrowed. | Rust |
class Person {{ int bar; }}
obj.bar=5; | class Person {{ public int bar; }}
obj.bar=5; | Make field public. | Java |
class = 'value' | class_name = 'value' | 'class' is a keyword. | Python |
if [ $temp = 69 ]; then | if [ "$temp" = 69 ]; then | Quote variable. | Shell |
let mut foo=67; let ref1=&mut foo; let ref2=&mut foo; | let mut foo=67; {{ let ref1=&mut foo; }} let ref2=&mut foo; | Only one mutable borrow. | Rust |
match num {{ 1 => {{}} }} | match num {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
fn baz() -> i32 {{ 61 }} | fn baz() -> i32 {{ 61 }} | Correct. | Rust |
status: result
status: test, | status: result
status: test | Remove comma. | YAML |
div {{ color=#333; }} | div {{ color: #333; }} | Use colon. | CSS |
if result = 47 {{}} | if result == 47 {{}} | Use ==. | Swift |
cin >> bar
cout << bar; | cin >> bar;
cout << bar; | Add semicolon. | C++ |
Post.save(); | Post.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
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