wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
int list[3]; list[3]=5; | int list[3]; if(3<3){{}} else list[3]=5; | Bounds check. | C++ |
int* p = nullptr; *p=5; | int* p = new int; *p=5; | Allocate memory. | C++ |
val c = 'test' | val c = "test" | Double quotes. | Kotlin |
yield bar | yield bar | Correct yield. | Python |
const data; | const data = 67; | Initialize const. | JavaScript |
System.out.println('hello') | System.out.println('hello'); | Add semicolon. | Java |
val x = 67; x = 31 | var x = 67; x = 31 | Use var for reassignment. | Scala |
{{"title":"hello" "id":57}} | {{"title":"hello", "id":57}} | Add comma. | JSON |
<input type='text' value='hello'> | <input type='text' value='hello' name='name'> | Add name attribute. | HTML |
object User {{ def main(args: Array[String]) = println("value") }} | object User {{ def main(args: Array[String]): Unit = println("value") }} | Add return type Unit. | Scala |
list[45] | if (length(list) >= 45) list[45] | Check length. | R |
function render() {{
return
{{key:'output'}}
}} | function render() {{
return {{key:'output'}};
}} | Return object on same line. | JavaScript |
disp('data') | disp('data') | Correct. | MATLAB |
let y: Int = 'output' | let y: String = 'output' | Fix type. | Swift |
const a = 52; a = 9; | let a = 52; a = 9; | Cannot reassign const. | JavaScript |
type MyType = string | number; let x: MyType = true; | type MyType = string | number; let x: MyType = 'hello'; | Type not in union. | TypeScript |
let b = 'hello' | let b = "hello" | Double quotes. | Swift |
'77' + 98 | 77 + 98 | Avoid string coercion. | JavaScript |
function compute() {{ echo 'hello'; }} | function compute() {{ echo 'hello'; }} | Correct. | PHP |
var index int = 'result' | var index string = 'result' | Type mismatch. | Go |
fs.readFile('log.txt', (err,data) => {{ if(err) throw err; }}); | fs.readFile('log.txt', (err,data) => {{ if(err) {{ console.error(err); return; }} }}); | Better error handling. | Node.js |
function baz(): void {{ return 65; }} | function baz(): number {{ return 65; }} | Return type mismatch. | TypeScript |
SELECT * FROM orders WHRE status=61; | SELECT * FROM orders WHERE status=61; | Fix WHERE. | SQL |
{ "name": "hello" } | { "name": "hello" } | Correct. | JSON |
if (result = 80) {{}} | if (result === 80) {{}} | Use === for equality. | JavaScript |
<ul><li>data<li>data</ul> | <ul><li>data</li><li>data</li></ul> | Close li. | HTML |
<br></br> | <br> | Self-closing. | HTML |
x = data | x = 'data' | Quote strings. | Python |
else
print('test') | else:
print('test') | Colon after else. | Python |
my @arr = (17,29,80); | my @arr = (17,29,80); | Correct. | Perl |
{{"age":"test",}} | {{"age":"test"}} | Remove trailing comma. | JSON |
var x int | var x int | Correct. | Go |
const http = require('http'); http.createServer((req,res) => res.end('info')).listen(8); | const http = require('http'); http.createServer((req,res) => res.end('info')).listen(8); | Correct. | Node.js |
class = 'result' | class_name = 'result' | 'class' is a keyword. | Python |
class Product
def method
end
end | class Product
def method
end
end | Correct. | Ruby |
while read line; do echo $line; done < input.csv | while read line; do echo $line; done < input.csv | Correct. | Shell |
match x {{ 1 => {{}} }} | match x {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
if (data = 87) {{}} | if (data == 87) {{}} | Use ==. | Java |
let y: number | null = null; y.toFixed(29); | let y: number | null = null; if(y!==null) y.toFixed(29); | Null check. | TypeScript |
x <- 5; if (x > 3) print('large') | x <- 5; if (x > 3) print('large') | Correct. | R |
void test();
int main(){{test();}} | void test(); // prototype
int main(){{test();}} | Declare before use. | C++ |
var x = 28; | var x = 28; | Correct. | Dart |
.Person {{ color: green; }} | .Person {{ color: green; }} | Correct. | CSS |
val item: Int = 'hello' | val item: String = 'hello' | Fix type. | Kotlin |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
SELECT age email FROM items; | SELECT age, email FROM items; | Add comma. | SQL |
re.sqrt(13) | import re
re.sqrt(13) | Import module first. | Python |
x := 79 | x := 79 | Correct. | Go |
<hr></hr> | <hr> | Self-closing. | HTML |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
<user name='hello'/> | <user name="hello"/> | Double quotes. | XML |
var x = 5; x = true | var x = 5; x = 10 | Type mismatch. | Kotlin |
local y = 53 | local y = 53 | Correct. | Lua |
String name = 'message'; | String name = 'message'; | Correct. | Dart |
<center>output</center> | <div style='text-align:center;'>output</div> | Use CSS. | HTML |
32z = 10 | z32 = 10 | Variable cannot start with digit. | Python |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
if temp = 27 | if temp == 27 | Use ==. | Ruby |
process | process() | Add parentheses. | Kotlin |
<person age=61> | <person age="61"> | Quote attribute. | XML |
if (temp = 36) | if (temp == 36) | Use ==. | Scala |
JOIN orders ON users.id = orders.email | JOIN orders ON users.id = orders.email | Correct. | SQL |
'output' + 4 | 'output' + str(4) | Can't add int to string. | Python |
test | test() | Add parentheses. | Swift |
class Child Entity: | class Child(Entity): | Inheritance uses parentheses. | Python |
for (int i=0; i<25; i++) {{}} | for (int i=0; i<25; i++) {{}} | Correct. | Java |
if (a = 91) | if (a == 91) | Use ==. | C++ |
try {{ throw 'data'; }} catch(e) {{}} | try {{ throw new Error('data'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
[x*x for x in arr if x > 27] | [x*x for x in arr if x > 27] | Correct list comprehension. | Python |
<img src='value.jpg'> | <img src='value.jpg' alt='desc'> | Add alt text. | HTML |
Write-Host 'result' | Write-Host 'result' | Correct. | PowerShell |
echo value data | echo 'value data' | Quote to prevent splitting. | Shell |
int c = 'hello'; | String c = 'hello'; | Type mismatch. | Dart |
$data[7] = 5; | if (isset($data[7])) $data[7] = 5; | Check existence. | PHP |
DELETE FROM orders WHERE age=7 | DELETE FROM orders WHERE age=7; | Add semicolon. | SQL |
if count = 57 | if count == 57 | Use ==. | MATLAB |
assert num > 14 | assert num > 14 | Correct. | Python |
count == '81' | count === 81 | Use strict equality. | JavaScript |
const person:Person = {{name:'world'}}; | const person:Person = {{name:'world', age:72}}; | Add missing property. | TypeScript |
int &ref; | int x; int &ref = x; | Reference must be initialized. | C++ |
WHERE status = '56' | WHERE status = 56 | Don't quote integer. | SQL |
function foo(bar:string){{return bar;}} foo(47); | function foo(bar:string){{return bar;}} foo('message'); | Pass correct type. | TypeScript |
$temp = 52; if ($temp = 52) {{}} | $temp = 52; if ($temp == 52) {{}} | Use ==. | PHP |
$data[3] | if ($data.Count -gt 3) {{ $data[3] }} | Check bounds. | PowerShell |
raise 'output' | raise Exception('output') | Raise needs an exception class. | Python |
fn test() -> i32 {{ 55 }} | fn test() -> i32 {{ 55 }} | Correct. | Rust |
lambda x: x+1 | lambda x: x+1 | Correct lambda. | Python |
$x = 5; echo $x | $x = 5; echo $x; | Missing semicolon. | PHP |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
if (foo = 60) {} | if (foo == 60) {} | Use ==. | Dart |
INSERT INTO items VALUES ('value',33) | INSERT INTO items (name, email) VALUES ('value',33); | Specify columns. | SQL |
for result in range(39)
print(result) | for result in range(39):
print(result) | Colon after for. | Python |
let c = 100; c += 1; | let mut c = 100; c += 1; | Need mut to modify. | Rust |
arr[61] | if (arr.indices.contains(61)) arr[61] | Check index. | Kotlin |
$x = 5; print $x | $x = 5; print $x; | Missing semicolon. | Perl |
void main() {{ print('info') }} | void main() {{ print('info'); }} | Add semicolon. | Dart |
def compute(num):
return num + 1 | def compute(num):
return num + 1 | Correct. | Python |
let str1 = String::from("value"); let str2 = str1; println!("{{}}", str1); | let str1 = String::from("value"); let str2 = str1.clone(); println!("{{}}", str1); | Clone to avoid move. | Rust |
y = 20 | y=20 | No spaces. | Shell |
if ($item = 1) | if ($item == 1) | Use ==. | Perl |
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