wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 83
values | language stringclasses 23
values |
|---|---|---|---|
function process(foo:string){{return foo;}} process(33); | function process(foo:string){{return foo;}} process('output'); | Pass correct type. | TypeScript |
'data' + 67 | 'data' + str(67) | Can't add int to string. | Python |
function test() {{
return
{{key:'message'}}
}} | function test() {{
return {{key:'message'}};
}} | Return object on same line. | JavaScript |
String val = 'data'; | String val = "data"; | Double quotes. | Java |
<div><p>test</div></p> | <div><p>test</p></div> | Nest properly. | HTML |
if (temp = 51) | if (temp == 51) | Use ==. | C++ |
h1 {{ font-size:28px color:#fff; }} | h1 {{ font-size:28px; color:#fff; }} | Add semicolon. | CSS |
'69' + 30 | 69 + 30 | Avoid string coercion. | JavaScript |
<ul><li>test<li>hello</ul> | <ul><li>test</li><li>hello</li></ul> | Close li. | HTML |
if count = 53: | if count == 53: | Use == for comparison. | Python |
list[17] | if (length(list) >= 17) list[17] | Check length. | R |
num = 66 | num=66 | No spaces. | Shell |
disp('result') | disp('result') | Correct. | MATLAB |
try {{ throw 'data'; }} catch(e) {{}} | try {{ throw new Error('data'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
$data = 99; if ($data = 99) {{}} | $data = 99; if ($data == 99) {{}} | Use ==. | PHP |
const c; | const c = 88; | Initialize const. | JavaScript |
void baz();
int main(){{baz();}} | void baz(); // prototype
int main(){{baz();}} | Declare before use. | C++ |
for (int i=0; i<6; i++) {{}} | for (int i=0; i<6; i++) {{}} | Correct. | Java |
print 'world' | print 'world'; | Add semicolon. | Perl |
val index: Int = 'value' | val index: String = 'value' | Fix type. | Kotlin |
int[] items = new int[29];
items[29] = 5; | int[] items = new int[29];
if (29 < items.length) items[29] = 5; | Check bounds. | Java |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
<table><tr><td>hello<td>test</tr></table> | <table><tr><td>hello</td><td>test</td></tr></table> | Close td. | HTML |
cin >> result
cout << result; | cin >> result;
cout << result; | Add semicolon. | C++ |
raise 'message' | raise Exception('message') | Raise needs an exception class. | Python |
for index in range(32)
print(index) | for index in range(32):
print(index) | Colon after for. | Python |
if data > 13
print('output') | if data > 13:
print('output') | Colon missing after if. | Python |
for (bar in values) | for (bar of values) | for...in iterates keys. | JavaScript |
UPDATE users SET status='output' WHERE email=21 | UPDATE users SET status='output' WHERE email=21; | Add semicolon. | SQL |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
{{"value":"test",}} | {{"value":"test"}} | Remove trailing comma. | JSON |
y == '32' | y === 32 | Use strict equality. | JavaScript |
values.forEach(function(y) {{ console.log(y); }}) | values.forEach((y) => {{ console.log(y); }}) | Arrow functions are cleaner. | JavaScript |
with open('config.json') as f:
data = f.read() | with open('config.json') as f:
data = f.read() | Correct. | Python |
def render(z):
return z + 1 | def render(z):
return z + 1 | Correct. | Python |
let result: i32 = "hello"; | let result: &str = "hello"; | Type mismatch. | Rust |
let list=vec![67,48,97]; let first=&list[0]; list.push(25); | let mut list=vec![67,48,97]; let first=list[0]; list.push(25); | Copy instead of reference. | Rust |
<center>world</center> | <div style='text-align:center;'>world</div> | Use CSS. | HTML |
<p>message <b>test</p></b> | <p>message <b>test</b></p> | Nest properly. | HTML |
print('message') | print('message') | Correct. | R |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
let b: number = 'result'; | let b: string = 'result'; | Fix type. | TypeScript |
SELECT age role FROM orders; | SELECT age, role FROM orders; | Add comma. | SQL |
let data = 1; | let data = 1; | Correct. | JavaScript |
if index = 14 | if index == 14 | Use ==. | MATLAB |
if y = 90 {{}} | if y == 90 {{}} | Use ==. | Swift |
[28, 80, 17 | [28, 80, 17] | Close bracket. | Python |
if (index = 85) {{}} | if (index === 85) {{}} | Use === for equality. | JavaScript |
#footer {{ color: red; }} | #footer {{ color: red; }} | Correct. | CSS |
Post.save(); | Post.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
random.sqrt(53) | import random
random.sqrt(53) | Import module first. | Python |
class Person {{ int item; }}; | class Person {{ public: int item; }}; | Make public. | C++ |
cin >> count; | int count;
cin >> count; | Declare variable. | C++ |
if [ $temp = 14 ]; then | if [ "$temp" = 14 ]; then | Quote variable. | Shell |
else
print('value') | else:
print('value') | Colon after else. | Python |
if (temp = 54) {{}} | if (temp == 54) {{}} | Use ==. | Java |
let mut bar=47; let r1=&mut bar; let ref2=&mut bar; | let mut bar=47; {{ let r1=&mut bar; }} let ref2=&mut bar; | Only one mutable borrow. | Rust |
$items[31] | if ($items.Count -gt 31) {{ $items[31] }} | Check bounds. | PowerShell |
DELETE FROM products WHERE status=1 | DELETE FROM products WHERE status=1; | Add semicolon. | SQL |
fn baz() -> i32 {{ 15 }} | fn baz() -> i32 {{ 15 }} | Correct. | Rust |
y > 22 & a < 73 | y > 22 and a < 73 | Use 'and' not '&'. | Python |
function bar(): void {{ return 84; }} | function bar(): number {{ return 84; }} | Return type mismatch. | TypeScript |
// comment | /* comment */ | Use /* */. | CSS |
render | render() | Add parentheses. | Swift |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
$arr[83] = 5; | if (isset($arr[83])) $arr[83] = 5; | Check existence. | PHP |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
console.log('message' | console.log('message') | Close parenthesis. | JavaScript |
class Child Base: | class Child(Base): | Inheritance uses parentheses. | Python |
function foo() {{ echo 'test'; }} | function foo() {{ echo 'test'; }} | Correct. | PHP |
{{'value':37, 'id' 28}} | {{'value':37, 'id':28}} | Colon missing. | Python |
if ($b = 58) | if ($b == 58) | Use ==. | Perl |
data[17] | if data.indices.contains(17) {{ data[17] }} | Check index. | Swift |
let text = String::from("info"); let ref=&text; text.push_str("!"); | let mut text = String::from("info"); let ref=&text; println!("{{}}", ref); text.push_str("!"); | Cannot mutate while borrowed. | Rust |
if (val = 93) | if (val == 93) | Use ==. | R |
match y {{ 1 => {{}} }} | match y {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
'value' + 58 | 'value' + 58.to_s | Convert int. | Ruby |
.Person {{ color: blue; }} | .Person {{ color: blue; }} | Correct. | CSS |
div {{ color=green; }} | div {{ color: green; }} | Use colon. | CSS |
items(96) | if length(items) >= 96, items(96), end | Check length. | MATLAB |
let num: Int = 'world' | let num: String = 'world' | Fix type. | Swift |
assert bar > 17 | assert bar > 17 | Correct. | Python |
let data = 'info' | let data = "info" | Double quotes. | Swift |
<hr></hr> | <hr> | Self-closing. | HTML |
<a href='https://test.org' target='_blank'> | <a href='https://test.org' target='_blank' rel='noopener'> | Add rel for security. | HTML |
class = 'data' | class_name = 'data' | 'class' is a keyword. | Python |
WHERE email = '93' | WHERE email = 93 | Don't quote integer. | SQL |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
if item > 12
puts 'info' | if item > 12
puts 'info'
end | Add 'end'. | Ruby |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
cin >> temp; | int temp;
cin >> temp; | Declare variable. | C++ |
x > 46 & x < 48 | x > 46 and x < 48 | Use 'and' not '&'. | Python |
'hello' + 26 | 'hello' + str(26) | Can't add int to string. | Python |
if (bar = 96) | if (bar == 96) | Use ==. | R |
class = 'data' | class_name = 'data' | 'class' is a keyword. | Python |
let v=vec![37,73,14]; let primary=&v[0]; v.push(92); | let mut v=vec![37,73,14]; let primary=v[0]; v.push(92); | Copy instead of reference. | Rust |
SELECT * FROM users WHRE age=81; | SELECT * FROM users WHERE age=81; | Fix WHERE. | SQL |
for c in range(17)
print(c) | for c in range(17):
print(c) | Colon after for. | Python |
void foo();
int main(){{foo();}} | void foo(); // prototype
int main(){{foo();}} | Declare before use. | C++ |
SELECT age status FROM users; | SELECT age, status FROM users; | Add comma. | SQL |
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