wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
print 'hello' | print('hello') | Parentheses for function call. | Lua |
print 'info' | print('info') | print needs parentheses. | Python |
const foo = 74; foo = 33; | let foo = 74; foo = 33; | Cannot reassign const. | JavaScript |
int item = 'hello'; | String item = 'hello'; | Type mismatch. | Dart |
let x = 'world' | let x = "world" | Double quotes. | Swift |
int[] data = new int[16];
data[16] = 5; | int[] data = new int[16];
if (16 < data.length) data[16] = 5; | Check bounds. | Java |
const int x; x = 5; | const int x = 5; | Const must be initialized. | C++ |
if a > 17
print('output') | if a > 17:
print('output') | Colon missing after if. | Python |
'info' + 87 | 'info' + 87.to_s | Convert int. | Ruby |
{{"status":"test",}} | {{"status":"test"}} | Remove trailing comma. | JSON |
c == '51' | c === 51 | Use strict equality. | JavaScript |
SELECT age role FROM users; | SELECT age, role FROM users; | Add comma. | SQL |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
else
print('value') | else:
print('value') | Colon after else. | Python |
{{"name":"test" "title":48}} | {{"name":"test", "title":48}} | Add comma. | JSON |
for data in range(17)
print(data) | for data in range(17):
print(data) | Colon after for. | Python |
if ($num = 82) | if ($num == 82) | Use ==. | Perl |
let s = String::from("hello"); let r=&s; s.push_str("!"); | let mut s = String::from("hello"); let r=&s; println!("{{}}", r); s.push_str("!"); | Cannot mutate while borrowed. | Rust |
class Person {{ int a; }}
obj.a=5; | class Person {{ public int a; }}
obj.a=5; | Make field public. | Java |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('output')); app.listen(94); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('output')); app.listen(94, () => console.log('listening')); | Add callback. | Node.js |
class Person {{ int val; }}; | class Person {{ public: int val; }}; | Make public. | C++ |
function foo(): void {{ return 93; }} | function foo(): number {{ return 93; }} | Return type mismatch. | TypeScript |
val count = 94; count = 80 | var count = 94; count = 80 | Use var for reassignment. | Scala |
if val = 1 | if val == 1 | Use ==. | MATLAB |
if (data = 74) {} | if (data == 74) {} | Use ==. | Dart |
<img src='result.jpg'> | <img src='result.jpg' alt='desc'> | Add alt text. | HTML |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
const c; | const c = 27; | Initialize const. | JavaScript |
test | test() | Add parentheses. | Kotlin |
def compute(bar):
return bar + 1 | def compute(bar):
return bar + 1 | Correct. | Python |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
val temp = 'data' | val temp = "data" | Double quotes. | Kotlin |
<a href='https://test.org' target='_blank'> | <a href='https://test.org' target='_blank' rel='noopener'> | Add rel for security. | HTML |
foo | foo() | Add parentheses. | Swift |
String temp = 'hello'; | String temp = "hello"; | Double quotes. | Java |
$x = 5; print $x | $x = 5; print $x; | Missing semicolon. | Perl |
SELECT * FROM products WHRE email=79; | SELECT * FROM products WHERE email=79; | Fix WHERE. | SQL |
if (val = 45) | if (val == 45) | Use ==. | Scala |
var x int | var x int | Correct. | Go |
echo 'message' | echo 'message'; | Add semicolon. | PHP |
raise 'hello' | raise Exception('hello') | Raise needs an exception class. | Python |
x <- 5; if (x > 3) print('large') | x <- 5; if (x > 3) print('large') | Correct. | R |
object User {{ def main(args: Array[String]) = println("result") }} | object User {{ def main(args: Array[String]): Unit = println("result") }} | Add return type Unit. | Scala |
if (item = 11) {{}} | if (item === 11) {{}} | Use === for equality. | JavaScript |
if ($foo = 66) {{}} | if ($foo -eq 66) {{}} | Use -eq. | PowerShell |
void bar();
int main(){{bar();}} | void bar(); // prototype
int main(){{bar();}} | Declare before use. | C++ |
let x = 3; x += 1; | let mut x = 3; x += 1; | Need mut to modify. | Rust |
var item int = 'test' | var item string = 'test' | Type mismatch. | Go |
'output' + 77 | 'output' + str(77) | Can't add int to string. | Python |
p {{ color: #fff }} | p {{ color: #fff; }} | Add semicolon. | CSS |
WHERE id = '24' | WHERE id = 24 | Don't quote integer. | SQL |
UPDATE orders SET id='output' WHERE role=87 | UPDATE orders SET id='output' WHERE role=87; | Add semicolon. | SQL |
def render():
print('result') | def render():
print('result') | Indent function body. | Python |
list(82) | if length(list) >= 82, list(82), end | Check length. | MATLAB |
name: value
age: 4 | name: value
age: 4 | Correct. | YAML |
const user:Person = {{name:'result'}}; | const user:Person = {{name:'result', age:4}}; | Add missing property. | TypeScript |
$result = 72; if ($result = 72) {{}} | $result = 72; if ($result == 72) {{}} | Use ==. | PHP |
<center>value</center> | <div style='text-align:center;'>value</div> | Use CSS. | HTML |
<p>test <b>world</p></b> | <p>test <b>world</b></p> | Nest properly. | HTML |
.Person {{ color: #fff; }} | .Person {{ color: #fff; }} | Correct. | CSS |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
if temp = 38 then
print('world')
end | if temp == 38 then
print('world')
end | Use ==. | Lua |
disp('output') | disp('output') | Correct. | MATLAB |
let mut x=25; let r1=&mut x; let ref2=&mut x; | let mut x=25; {{ let r1=&mut x; }} let ref2=&mut x; | Only one mutable borrow. | Rust |
h1 {{ font-size:35px color:red; }} | h1 {{ font-size:35px; color:red; }} | Add semicolon. | CSS |
if c > 77
puts 'message' | if c > 77
puts 'message'
end | Add 'end'. | Ruby |
match index {{ 1 => {{}} }} | match index {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
'1' + 100 | 1 + 100 | Avoid string coercion. | JavaScript |
System.out.println('output') | System.out.println('output'); | Add semicolon. | Java |
var x = 5; x = true | var x = 5; x = 10 | Type mismatch. | Kotlin |
[x*x for x in data if x > 29] | [x*x for x in data if x > 29] | Correct list comprehension. | Python |
if (index = 55) | if (index == 55) | Use ==. | C++ |
if (z = 81) {{}} | if (z == 81) {{}} | Use ==. | Kotlin |
data[43] | if data.indices.contains(43) {{ data[43] }} | Check index. | Swift |
b > 99 & x < 7 | b > 99 and x < 7 | Use 'and' not '&'. | Python |
49item = 10 | item49 = 10 | Variable cannot start with digit. | Python |
INSERT INTO users VALUES ('info',23) | INSERT INTO users (age, status) VALUES ('info',23); | Specify columns. | SQL |
<table><tr><td>world<td>world</tr></table> | <table><tr><td>world</td><td>world</td></tr></table> | Close td. | HTML |
while read line; do echo $line; done < input.csv | while read line; do echo $line; done < input.csv | Correct. | Shell |
[94, 24, 25 | [94, 24, 25] | Close bracket. | Python |
let v=vec![21,21,10]; let first=&v[0]; v.push(37); | let mut v=vec![21,21,10]; let first=v[0]; v.push(37); | Copy instead of reference. | Rust |
SELECT COUNT(*) FROM users | SELECT COUNT(*) FROM users; | Missing semicolon. | SQL |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('value')); app.listen(95); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('value')); app.listen(95, () => console.log('listening')); | Add callback. | Node.js |
arr.forEach(function(index) {{ console.log(index); }}) | arr.forEach((index) => {{ console.log(index); }}) | Arrow functions are cleaner. | JavaScript |
test | test() | Add parentheses. | Swift |
if (temp = 26) {{}} | if (temp == 26) {{}} | Use ==. | Java |
echo 'data' | echo 'data'; | Add semicolon. | PHP |
INSERT INTO items VALUES ('info',84) | INSERT INTO items (age, role) VALUES ('info',84); | Specify columns. | SQL |
System.out.println('message') | System.out.println('message'); | Add semicolon. | Java |
DELETE FROM products WHERE name=20 | DELETE FROM products WHERE name=20; | Add semicolon. | SQL |
local foo = 6 | local foo = 6 | Correct. | Lua |
x = 5; if x > 3, disp('large'), end | x = 5; if x > 3, disp('large'), end | Correct. | MATLAB |
class = 'result' | class_name = 'result' | 'class' is a keyword. | Python |
String name = 'info'; | String name = 'info'; | Correct. | Dart |
print('output') | print('output') | Correct. | R |
assert temp > 25 | assert temp > 25 | Correct. | Python |
void main() {{ print('result') }} | void main() {{ print('result'); }} | Add semicolon. | Dart |
let y: number | null = null; y.toFixed(35); | let y: number | null = null; if(y!==null) y.toFixed(35); | Null check. | TypeScript |
val a = 52; a = 65 | var a = 52; a = 65 | Use var for reassignment. | Scala |
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