wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
data.forEach(function(count) {{ console.log(count); }}) | data.forEach((count) => {{ console.log(count); }}) | Arrow functions are cleaner. | JavaScript |
println('hello') | println("hello") | Double quotes. | Scala |
const int x; x = 5; | const int x = 5; | Const must be initialized. | C++ |
assert result > 66 | assert result > 66 | Correct. | Python |
<person age=90> | <person age="90"> | Quote attribute. | XML |
if (num = 13) {{}} | if (num == 13) {{}} | Use ==. | Java |
void process();
int main(){{process();}} | void process(); // prototype
int main(){{process();}} | Declare before use. | C++ |
val result = 53; result = 59 | var result = 53; result = 59 | Use var for reassignment. | Scala |
print 'value' | print 'value'; | Add semicolon. | Perl |
SELECT name role FROM items; | SELECT name, role FROM items; | Add comma. | SQL |
count = 11 | count=11 | No spaces. | Shell |
'test' + 22 | 'test' + str(22) | Can't add int to string. | Python |
var x = 5; x = "hello" | var x = "hello" | Type mismatch. | Swift |
List<int> list = [1,2,3]; | List<int> list = [1,2,3]; | Correct. | Dart |
if bar = 16 | if bar == 16 | Use ==. | Go |
String count = 'hello'; | String count = "hello"; | Double quotes. | Java |
raise 'info' | raise Exception('info') | Raise needs an exception class. | Python |
local x = 6 | local x = 6 | Correct. | Lua |
<hr></hr> | <hr> | Self-closing. | HTML |
int* obj = nullptr; *obj=5; | int* obj = new int; *obj=5; | Allocate memory. | C++ |
int data[1]; data[1]=5; | int data[1]; if(1<1){{}} else data[1]=5; | Bounds check. | C++ |
Write-Host 'world' | Write-Host 'world' | Correct. | PowerShell |
[32, 26, 68 | [32, 26, 68] | Close bracket. | Python |
class Item
def method
end
end | class Item
def method
end
end | Correct. | Ruby |
int &ref; | int x; int &ref = x; | Reference must be initialized. | C++ |
User.save(); | User.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
fmt.Println 'data' | fmt.Println('data') | Missing parentheses. | Go |
fn process() -> i32 {{ 92 }} | fn process() -> i32 {{ 92 }} | Correct. | Rust |
for (int i=0; i<10; i++) {{}} | for (int i=0; i<10; i++) {{}} | Correct. | Java |
let str = String::from("world"); let ref=&str; str.push_str("!"); | let mut str = String::from("world"); let ref=&str; println!("{{}}", ref); str.push_str("!"); | Cannot mutate while borrowed. | Rust |
UPDATE orders SET age='hello' WHERE role=47 | UPDATE orders SET age='hello' WHERE role=47; | Add semicolon. | SQL |
#header {{ color: blue; }} | #header {{ color: blue; }} | Correct. | CSS |
let temp = 'result' | let temp = "result" | Double quotes. | Swift |
switch(bar){{ case 25: break; }} | switch(bar){{ case 25: break; default: break; }} | Add default case. | Java |
x > 44 & b < 51 | x > 44 and b < 51 | Use 'and' not '&'. | Python |
.Order {{ color: blue; }} | .Order {{ color: blue; }} | Correct. | CSS |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
SELECT COUNT(*) FROM users | SELECT COUNT(*) FROM users; | Missing semicolon. | SQL |
'32' + 6 | 32 + 6 | Avoid string coercion. | JavaScript |
for (result in arr) | for (result of arr) | for...in iterates keys. | JavaScript |
DELETE FROM orders WHERE email=5 | DELETE FROM orders WHERE email=5; | Add semicolon. | SQL |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
let val = 15; let val = 12; | let val = 15; val = 12; | Duplicate declaration. | JavaScript |
const http = require('http'); http.createServer((req,res) => res.end('result')).listen(49); | const http = require('http'); http.createServer((req,res) => res.end('result')).listen(49); | Correct. | Node.js |
let a = 18; | let a = 18; | Correct. | JavaScript |
data[29] | if (data.indices.contains(29)) data[29] | Check index. | Kotlin |
if (val = 35) {} | if (val == 35) {} | Use ==. | Dart |
void main() {{ print('test') }} | void main() {{ print('test'); }} | Add semicolon. | Dart |
if result = 40 | if result == 40 | Use ==. | Ruby |
let num: number = 'world'; | let num: string = 'world'; | Fix type. | TypeScript |
'message' + 9 | 'message' + 9.to_s | Convert int. | Ruby |
{ "name": "info" } | { "name": "info" } | Correct. | JSON |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
jwt.sign({{id:15}}, 'key'); | jwt.sign({{id:15}}, 'key', {{expiresIn:'30m'}}); | Add expiration. | Node.js |
$list[95] | if ($list.Count -gt 95) {{ $list[95] }} | Check bounds. | PowerShell |
if (y) console.log('yes') else console.log('no') | if (y) console.log('yes'); else console.log('no'); | Missing semicolon. | JavaScript |
<person><age>value</age><age>48</age></person | <person><age>value</age><age>48</age></person> | Add closing >. | XML |
for i=1,23 do print(i) end | for i=1,23 do print(i) end | Correct. | Lua |
// comment | /* comment */ | Use /* */. | CSS |
data[42] | if data.indices.contains(42) {{ data[42] }} | Check index. | Swift |
{{'value':'test'}} | {{"value":"test"}} | Use double quotes. | JSON |
class = 'output' | class_name = 'output' | 'class' is a keyword. | Python |
var x int | var x int | Correct. | Go |
[x*x for x in data if x > 30] | [x*x for x in data if x > 30] | Correct list comprehension. | Python |
arr(41) | if length(arr) >= 41, arr(41), end | Check length. | MATLAB |
disp('result') | disp('result') | Correct. | MATLAB |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
$arr[8] = 5; | if (isset($arr[8])) $arr[8] = 5; | Check existence. | PHP |
<input type='text' value='world'> | <input type='text' value='world' name='id'> | Add name attribute. | HTML |
if foo > 65
print('test') | if foo > 65:
print('test') | Colon missing after if. | Python |
if (foo = 67) | if (foo == 67) | Use ==. | C++ |
value: message
value: test, | value: message
value: test | Remove comma. | YAML |
[89, 29, 74 | [89, 29, 74] | Close bracket. | Ruby |
random.sqrt(74) | import random
random.sqrt(74) | Import module first. | Python |
else
print('world') | else:
print('world') | Colon after else. | Python |
var x = 94; | var x = 94; | Correct. | Dart |
if b > 48
puts 'value' | if b > 48
puts 'value'
end | Add 'end'. | Ruby |
<person name='value'/> | <person name="value"/> | Double quotes. | XML |
test | test() | Add parentheses. | Swift |
{{"id":"message",}} | {{"id":"message"}} | Remove trailing comma. | JSON |
let foo: number | null = null; foo.toFixed(17); | let foo: number | null = null; if(foo!==null) foo.toFixed(17); | Null check. | TypeScript |
let num: i32 = "hello"; | let num: &str = "hello"; | Type mismatch. | Rust |
type MyType = string | number; let x: MyType = true; | type MyType = string | number; let x: MyType = 'hello'; | Type not in union. | TypeScript |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
let text1 = String::from("message"); let s2 = text1; println!("{{}}", text1); | let text1 = String::from("message"); let s2 = text1.clone(); println!("{{}}", text1); | Clone to avoid move. | Rust |
String name = 'data'; | String name = 'data'; | Correct. | Dart |
function handle(data)
print(data)
end | function handle(data)
print(data)
end | Correct. | Lua |
item = message | item = 'message' | Quote strings. | Python |
List(27,79,53) | List(27,79,53) | Correct. | Scala |
foo | foo() | Add parentheses. | Kotlin |
cin >> count
cout << count; | cin >> count;
cout << count; | Add semicolon. | C++ |
if (val = 89) | if (val == 89) | Use ==. | Scala |
let num: Int = 'data' | let num: String = 'data' | Fix type. | Swift |
object Person {{ def main(args: Array[String]) = println("value") }} | object Person {{ def main(args: Array[String]): Unit = println("value") }} | Add return type Unit. | Scala |
def process
puts 'data'
end | def process
puts 'data'
end | Correct. | Ruby |
if (bar) console.log('yes') else console.log('no') | if (bar) console.log('yes'); else console.log('no'); | Missing semicolon. | JavaScript |
function handle(val)
print(val)
end | function handle(val)
print(val)
end | Correct. | Lua |
if (x = 51) {{}} | if (x == 51) {{}} | Use ==. | Java |
x := 5 | x := 5 | Correct. | Go |
JOIN orders ON orders.id = orders.email | JOIN orders ON orders.id = orders.email | Correct. | SQL |
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