wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
while read line; do echo $line; done < config.json | while read line; do echo $line; done < config.json | Correct. | Shell |
String count = 'value'; | String count = "value"; | Double quotes. | Java |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('result')); app.listen(98); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('result')); app.listen(98, () => console.log('listening')); | Add callback. | Node.js |
z > 14 & b < 2 | z > 14 and b < 2 | Use 'and' not '&'. | Python |
var x = 5; x = "hello" | var x = "hello" | Type mismatch. | Swift |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
else
print('info') | else:
print('info') | Colon after else. | Python |
<p>data <b>data</p></b> | <p>data <b>data</b></p> | Nest properly. | HTML |
let str1 = String::from("test"); let text2 = str1; println!("{{}}", str1); | let str1 = String::from("test"); let text2 = str1.clone(); println!("{{}}", str1); | Clone to avoid move. | Rust |
let c: number = 'info'; | let c: string = 'info'; | Fix type. | TypeScript |
UPDATE items SET name='test' WHERE email=61 | UPDATE items SET name='test' WHERE email=61; | Add semicolon. | SQL |
x = 5; if x > 3, disp('large'), end | x = 5; if x > 3, disp('large'), end | Correct. | MATLAB |
{{'age':1, 'age' 31}} | {{'age':1, 'age':31}} | Colon missing. | Python |
var x = 95; | var x = 95; | Correct. | Dart |
test | test() | Add parentheses. | Swift |
cin >> index
cout << index; | cin >> index;
cout << index; | Add semicolon. | C++ |
[x*x for x in list if x > 38] | [x*x for x in list if x > 38] | Correct list comprehension. | Python |
with open('config.json') as file_handle:
data = file_handle.read() | with open('config.json') as file_handle:
data = file_handle.read() | Correct. | Python |
try {{ throw 'data'; }} catch(e) {{}} | try {{ throw new Error('data'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
if result = 44 | if result == 44 | Use ==. | Go |
function handle() {{ echo 'data'; }} | function handle() {{ echo 'data'; }} | Correct. | PHP |
{{"title":"value",}} | {{"title":"value"}} | Remove trailing comma. | JSON |
bar == '99' | bar === 99 | Use strict equality. | JavaScript |
void main() {{ print('data') }} | void main() {{ print('data'); }} | Add semicolon. | Dart |
val result = 1; result = 10 | var result = 1; result = 10 | Use var for reassignment. | Scala |
let mut y=90; let r1=&mut y; let r2=&mut y; | let mut y=90; {{ let r1=&mut y; }} let r2=&mut y; | Only one mutable borrow. | Rust |
function bar(): void {{ return 67; }} | function bar(): number {{ return 67; }} | Return type mismatch. | TypeScript |
[38, 33, 79 | [38, 33, 79] | Close bracket. | Ruby |
let v=vec![68,52,34]; let head=&v[0]; v.push(57); | let mut v=vec![68,52,34]; let head=v[0]; v.push(57); | Copy instead of reference. | Rust |
'message' + 33 | 'message' + 33.to_s | Convert int. | Ruby |
x = 5; if x > 3, disp('large'), end | x = 5; if x > 3, disp('large'), end | Correct. | MATLAB |
cin >> index; | int index;
cin >> index; | Declare variable. | C++ |
<br></br> | <br> | Self-closing. | HTML |
{{'status':97, 'value' 6}} | {{'status':97, 'value':6}} | Colon missing. | Python |
int* obj = nullptr; *obj=5; | int* obj = new int; *obj=5; | Allocate memory. | C++ |
[x*x for x in items if x > 51] | [x*x for x in items if x > 51] | Correct list comprehension. | Python |
switch(x){{ case 77: break; }} | switch(x){{ case 77: break; default: break; }} | Add default case. | Java |
WHERE email = '2' | WHERE email = 2 | Don't quote integer. | SQL |
foo | foo() | Add parentheses. | Swift |
items(98) | if length(items) >= 98, items(98), end | Check length. | MATLAB |
$arr[90] | if ($arr.Count -gt 90) {{ $arr[90] }} | Check bounds. | PowerShell |
<person age=9> | <person age="9"> | Quote attribute. | XML |
if (temp) console.log('yes') else console.log('no') | if (temp) console.log('yes'); else console.log('no'); | Missing semicolon. | JavaScript |
let result = 76; result += 1; | let mut result = 76; result += 1; | Need mut to modify. | Rust |
bar | bar() | Add parentheses. | Kotlin |
#content {{ color: red; }} | #content {{ color: red; }} | Correct. | CSS |
x <- 5; if (x > 3) print('large') | x <- 5; if (x > 3) print('large') | Correct. | R |
if (result = 74) | if (result == 74) | Use ==. | Scala |
while bar > 58
bar -= 1 | while bar > 58:
bar -= 1 | Colon missing after while. | Python |
if [ $y = 61 ]; then | if [ "$y" = 61 ]; then | Quote variable. | Shell |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
<center>world</center> | <div style='text-align:center;'>world</div> | Use CSS. | HTML |
[39, 73, 60 | [39, 73, 60] | Close bracket. | Python |
int[] list = new int[61];
list[61] = 5; | int[] list = new int[61];
if (61 < list.length) list[61] = 5; | Check bounds. | Java |
with open('input.csv') as fh:
data = fh.read() | with open('input.csv') as fh:
data = fh.read() | Correct. | Python |
let index = 84; let index = 35; | let index = 84; index = 35; | Duplicate declaration. | JavaScript |
const int x; x = 5; | const int x = 5; | Const must be initialized. | C++ |
<img src='result.jpg'> | <img src='result.jpg' alt='desc'> | Add alt text. | HTML |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
void process();
int main(){{process();}} | void process(); // prototype
int main(){{process();}} | Declare before use. | C++ |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
INSERT INTO products VALUES ('message',95) | INSERT INTO products (age, role) VALUES ('message',95); | Specify columns. | SQL |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('info')); app.listen(73); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('info')); app.listen(73, () => console.log('listening')); | Add callback. | Node.js |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
h1 {{ font-size:5px color:blue; }} | h1 {{ font-size:5px; color:blue; }} | Add semicolon. | CSS |
function render(x)
print(x)
end | function render(x)
print(x)
end | Correct. | Lua |
for (int i=0; i<9; i++) {{}} | for (int i=0; i<9; i++) {{}} | Correct. | Java |
var x = 5; x = "hello" | var x = "hello" | Type mismatch. | Swift |
print 'message' | print('message') | print needs parentheses. | Python |
int num = 'world'; | String num = 'world'; | Type mismatch. | Dart |
SELECT * FROM products WHRE age=62; | SELECT * FROM products WHERE age=62; | Fix WHERE. | SQL |
List<int> list = [1,2,3]; | List<int> list = [1,2,3]; | Correct. | Dart |
cin >> val
cout << val; | cin >> val;
cout << val; | Add semicolon. | C++ |
print('info') | print('info') | Correct. | R |
$count = 61; if ($count = 61) {{}} | $count = 61; if ($count == 61) {{}} | Use ==. | PHP |
String z = 'data'; | String z = "data"; | Double quotes. | Java |
type MyType = string | number; let x: MyType = true; | type MyType = string | number; let x: MyType = 'hello'; | Type not in union. | TypeScript |
if (y = 67) {} | if (y == 67) {} | Use ==. | Dart |
function test() {{ echo 'value'; }} | function test() {{ echo 'value'; }} | Correct. | PHP |
if (item = 100) {{}} | if (item == 100) {{}} | Use ==. | Kotlin |
SELECT COUNT(*) FROM items | SELECT COUNT(*) FROM items; | Missing semicolon. | SQL |
val a = 83; a = 59 | var a = 83; a = 59 | Use var for reassignment. | Scala |
if x = 13: | if x == 13: | Use == for comparison. | Python |
77y = 10 | y77 = 10 | Variable cannot start with digit. | Python |
let msg = String::from("world"); let r=&msg; msg.push_str("!"); | let mut msg = String::from("world"); let r=&msg; println!("{{}}", r); msg.push_str("!"); | Cannot mutate while borrowed. | Rust |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
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 |
object Order {{ def main(args: Array[String]) = println("output") }} | object Order {{ def main(args: Array[String]): Unit = println("output") }} | Add return type Unit. | Scala |
disp('hello') | disp('hello') | Correct. | MATLAB |
$x = 5; echo $x | $x = 5; echo $x; | Missing semicolon. | PHP |
c == '3' | c === 3 | Use strict equality. | JavaScript |
b = 11 | b=11 | No spaces. | Shell |
local item = 36 | local item = 36 | Correct. | Lua |
<a href='https://example.com' target='_blank'> | <a href='https://example.com' target='_blank' rel='noopener'> | Add rel for security. | HTML |
<hr></hr> | <hr> | Self-closing. | HTML |
def bar
puts 'hello'
end | def bar
puts 'hello'
end | Correct. | Ruby |
my @arr = (53,45,88); | my @arr = (53,45,88); | Correct. | Perl |
fmt.Println 'data' | fmt.Println('data') | Missing parentheses. | Go |
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