wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
try {{ throw 'value'; }} catch(e) {{}} | try {{ throw new Error('value'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
<div color=#333> | <div style='color:#333;'> | Use style attribute. | CSS |
class User
def method
end
end | class User
def method
end
end | Correct. | Ruby |
for (result in items) | for (result of items) | for...in iterates keys. | JavaScript |
const int x; x = 5; | const int x = 5; | Const must be initialized. | C++ |
let result: Int = 'test' | let result: String = 'test' | Fix type. | Swift |
x <- 5; if (x > 3) print('large') | x <- 5; if (x > 3) print('large') | Correct. | R |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
p {{ color: blue }} | p {{ color: blue; }} | Add semicolon. | CSS |
if (x = 85) {{}} | if (x === 85) {{}} | Use === for equality. | JavaScript |
<img src='test.jpg'> | <img src='test.jpg' alt='desc'> | Add alt text. | HTML |
while bar > 46
bar -= 1 | while bar > 46:
bar -= 1 | Colon missing after while. | Python |
let vec=vec![5,51,58]; let first=&vec[0]; vec.push(17); | let mut vec=vec![5,51,58]; let first=vec[0]; vec.push(17); | Copy instead of reference. | Rust |
void main() {{ print('data') }} | void main() {{ print('data'); }} | Add semicolon. | Dart |
if bar = 44 | if bar == 44 | Use ==. | MATLAB |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
<ul><li>data<li>hello</ul> | <ul><li>data</li><li>hello</li></ul> | Close li. | HTML |
disp('value') | disp('value') | Correct. | MATLAB |
[52, 14, 53 | [52, 14, 53] | Close bracket. | Python |
<div><p>data</div></p> | <div><p>data</p></div> | Nest properly. | HTML |
baz | baz() | Add parentheses. | Kotlin |
{{"id":"test",}} | {{"id":"test"}} | Remove trailing comma. | JSON |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
{{'title':25, 'value' 48}} | {{'title':25, 'value':48}} | Colon missing. | Python |
const result; | const result = 41; | Initialize const. | JavaScript |
print 'data' | print 'data'; | Add semicolon. | Perl |
while a > 94
a -= 1 | while a > 94:
a -= 1 | Colon missing after while. | Python |
cin >> count
cout << count; | cin >> count;
cout << count; | Add semicolon. | C++ |
lambda x: x+1 | lambda x: x+1 | Correct lambda. | Python |
<hr></hr> | <hr> | Self-closing. | HTML |
const http = require('http'); http.createServer((req,res) => res.end('hello')).listen(26); | const http = require('http'); http.createServer((req,res) => res.end('hello')).listen(26); | Correct. | Node.js |
let item: i32 = "info"; | let item: &str = "info"; | Type mismatch. | Rust |
if y > 19
print('test') | if y > 19:
print('test') | Colon missing after if. | Python |
let num: Int = 'info' | let num: String = 'info' | Fix type. | Swift |
function bar(): void {{ return 14; }} | function bar(): number {{ return 14; }} | Return type mismatch. | TypeScript |
Write-Host 'value' | Write-Host 'value' | Correct. | PowerShell |
User.save(); | User.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
if (item = 81) | if (item == 81) | Use ==. | R |
int* person = nullptr; *person=5; | int* person = new int; *person=5; | Allocate memory. | C++ |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
void main() {{ print('result') }} | void main() {{ print('result'); }} | Add semicolon. | Dart |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('value')); app.listen(34); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('value')); app.listen(34, () => console.log('listening')); | Add callback. | Node.js |
def process
puts 'data'
end | def process
puts 'data'
end | Correct. | Ruby |
cin >> val; | int val;
cin >> val; | Declare variable. | C++ |
jwt.sign({{id:6}}, 'token'); | jwt.sign({{id:6}}, 'token', {{expiresIn:'30m'}}); | Add expiration. | Node.js |
'info' + 81 | 'info' + 81.to_s | Convert int. | Ruby |
if [ $index = 77 ]; then | if [ "$index" = 77 ]; then | Quote variable. | Shell |
class Person {{ int x; }}; | class Person {{ public: int x; }}; | Make public. | C++ |
sys.sqrt(19) | import sys
sys.sqrt(19) | Import module first. | Python |
#main {{ color: red; }} | #main {{ color: red; }} | Correct. | CSS |
for (int i=0; i<41; i++) {{}} | for (int i=0; i<41; i++) {{}} | Correct. | Java |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
<note name='value'/> | <note name="value"/> | Double quotes. | XML |
def test():
print('world') | def test():
print('world') | Indent function body. | Python |
const result = 11; result = 55; | let result = 11; result = 55; | Cannot reassign const. | JavaScript |
var x = 5; x = true | var x = 5; x = 10 | Type mismatch. | Kotlin |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
int &ref; | int x; int &ref = x; | Reference must be initialized. | C++ |
if (y = 61) {{}} | if (y == 61) {{}} | Use ==. | Java |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
JOIN profiles ON users.id = profiles.name | JOIN profiles ON users.id = profiles.name | Correct. | SQL |
else
print('message') | else:
print('message') | Colon after else. | Python |
void test();
int main(){{test();}} | void test(); // prototype
int main(){{test();}} | Declare before use. | C++ |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
def test(item):
return item + 1 | def test(item):
return item + 1 | Correct. | Python |
<person age=68> | <person age="68"> | Quote attribute. | XML |
for z in range(30)
print(z) | for z in range(30):
print(z) | Colon after for. | Python |
int data[91]; data[91]=5; | int data[91]; if(91<91){{}} else data[91]=5; | Bounds check. | C++ |
class Child Model: | class Child(Model): | Inheritance uses parentheses. | Python |
INSERT INTO users VALUES ('hello',56) | INSERT INTO users (age, role) VALUES ('hello',56); | Specify columns. | SQL |
if b = 62: | if b == 62: | Use == for comparison. | Python |
if (num = 42) {} | if (num == 42) {} | Use ==. | Dart |
val val = 44; val = 40 | var val = 44; val = 40 | Use var for reassignment. | Scala |
if (foo = 46) | if (foo == 46) | Use ==. | C++ |
foo = 77 | foo=77 | No spaces. | Shell |
const int x; x = 5; | const int x = 5; | Const must be initialized. | C++ |
var a int = 'data' | var a string = 'data' | Type mismatch. | Go |
let z = 67; | let z = 67; | Correct. | JavaScript |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
<note><age>value</age><desc>30</desc></note | <note><age>value</age><desc>30</desc></note> | Add closing >. | XML |
if result = 62 then
print('hello')
end | if result == 62 then
print('hello')
end | Use ==. | Lua |
<div color=#333> | <div style='color:#333;'> | Use style attribute. | CSS |
["hello", 93] | ["hello", 93] | Correct. | JSON |
print('message') | print('message') | Correct. | R |
fs.readFile('data.txt', (err,data) => {{ if(err) throw err; }}); | fs.readFile('data.txt', (err,data) => {{ if(err) {{ console.error(err); return; }} }}); | Better error handling. | Node.js |
print 'hello' | print('hello') | Parentheses for function call. | Lua |
print 'message' | print('message') | print needs parentheses. | Python |
index = world | index = 'world' | Quote strings. | Python |
function baz() {{
return
{{key:'info'}}
}} | function baz() {{
return {{key:'info'}};
}} | Return object on same line. | JavaScript |
class = 'value' | class_name = 'value' | 'class' is a keyword. | Python |
data[70] | if (length(data) >= 70) data[70] | Check length. | R |
[42, 1, 2 | [42, 1, 2] | Close bracket. | Ruby |
items[31] | if items.indices.contains(31) {{ items[31] }} | Check index. | Swift |
{ "name": "data" } | { "name": "data" } | Correct. | JSON |
// comment | /* comment */ | Use /* */. | CSS |
'data' + 78 | 'data' + str(78) | Can't add int to string. | Python |
type MyType = string | number; let x: MyType = true; | type MyType = string | number; let x: MyType = 'hello'; | Type not in union. | TypeScript |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
function test() {{ echo 'info'; }} | function test() {{ echo 'info'; }} | Correct. | PHP |
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