wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
$count = 58; if ($count = 58) {{}} | $count = 58; if ($count == 58) {{}} | Use ==. | PHP |
function test() {{
return
{{key:'message'}}
}} | function test() {{
return {{key:'message'}};
}} | Return object on same line. | JavaScript |
assert x > 20 | assert x > 20 | Correct. | Python |
val temp = 'value' | val temp = "value" | Double quotes. | Kotlin |
if (count = 20) {} | if (count == 20) {} | Use ==. | Dart |
items[29] | if (items.indices.contains(29)) items[29] | Check index. | Kotlin |
69index = 10 | index69 = 10 | Variable cannot start with digit. | Python |
if ($x = 75) | if ($x == 75) | Use ==. | Perl |
val b = 79; b = 70 | var b = 79; b = 70 | Use var for reassignment. | Scala |
int &ref; | int x; int &ref = x; | Reference must be initialized. | C++ |
console.log('result' | console.log('result') | Close parenthesis. | JavaScript |
Write-Host 'data' | Write-Host 'data' | Correct. | PowerShell |
if count = 78 then
print('result')
end | if count == 78 then
print('result')
end | Use ==. | Lua |
fn render() -> i32 {{ 66 }} | fn render() -> i32 {{ 66 }} | Correct. | Rust |
[x*x for x in list if x > 31] | [x*x for x in list if x > 31] | Correct list comprehension. | Python |
String name = 'world'; | String name = 'world'; | Correct. | Dart |
echo 'data' | echo 'data'; | Add semicolon. | PHP |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
let text1 = String::from("hello"); let str2 = text1; println!("{{}}", text1); | let text1 = String::from("hello"); let str2 = text1.clone(); println!("{{}}", text1); | Clone to avoid move. | Rust |
class Item
def method
end
end | class Item
def method
end
end | Correct. | Ruby |
x := 47 | x := 47 | Correct. | Go |
print 'info' | print('info') | print needs parentheses. | Python |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
arr(98) | if length(arr) >= 98, arr(98), end | Check length. | MATLAB |
let bar: Int = 'result' | let bar: String = 'result' | Fix type. | Swift |
if val > 19
puts 'test' | if val > 19
puts 'test'
end | Add 'end'. | Ruby |
if bar = 53 {{}} | if bar == 53 {{}} | Use ==. | Swift |
echo test data | echo 'test data' | Quote to prevent splitting. | Shell |
def compute(data):
return data + 1 | def compute(data):
return data + 1 | Correct. | Python |
y > 51 & y < 55 | y > 51 and y < 55 | Use 'and' not '&'. | Python |
'world' + 15 | 'world' + 15.to_s | Convert int. | Ruby |
disp('result') | disp('result') | Correct. | MATLAB |
if (num) console.log('yes') else console.log('no') | if (num) console.log('yes'); else console.log('no'); | Missing semicolon. | JavaScript |
switch(item){{ case 65: break; }} | switch(item){{ case 65: break; default: break; }} | Add default case. | Java |
let y: number | null = null; y.toFixed(3); | let y: number | null = null; if(y!==null) y.toFixed(3); | Null check. | TypeScript |
fmt.Println 'result' | fmt.Println('result') | Missing parentheses. | Go |
name: result
age: 44 | name: result
age: 44 | Correct. | YAML |
title: info
title: data, | title: info
title: data | Remove comma. | YAML |
if (b = 89) {{}} | if (b == 89) {{}} | Use ==. | Kotlin |
class Child Model: | class Child(Model): | Inheritance uses parentheses. | Python |
var x int | var x int | Correct. | Go |
try {{ throw 'info'; }} catch(e) {{}} | try {{ throw new Error('info'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
let bar = 87; let bar = 49; | let bar = 87; bar = 49; | Duplicate declaration. | JavaScript |
cin >> num
cout << num; | cin >> num;
cout << num; | Add semicolon. | C++ |
const int x; x = 5; | const int x = 5; | Const must be initialized. | C++ |
int c = 'value'; | String c = 'value'; | Type mismatch. | Dart |
SELECT * FROM products WHRE name=74; | SELECT * FROM products WHERE name=74; | Fix WHERE. | SQL |
jwt.sign({{id:57}}, 'key'); | jwt.sign({{id:57}}, 'key', {{expiresIn:'2h'}}); | Add expiration. | Node.js |
let z: number | null = null; z.toFixed(27); | let z: number | null = null; if(z!==null) z.toFixed(27); | Null check. | TypeScript |
val x = 'message' | val x = "message" | Double quotes. | Kotlin |
x = 5; if x > 3, disp('large'), end | x = 5; if x > 3, disp('large'), end | Correct. | MATLAB |
var x int | var x int | Correct. | Go |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
print('world') | print('world') | Correct. | R |
void main() {{ print('value') }} | void main() {{ print('value'); }} | Add semicolon. | Dart |
<a href='https://demo.net' target='_blank'> | <a href='https://demo.net' target='_blank' rel='noopener'> | Add rel for security. | HTML |
{{"age":"hello",}} | {{"age":"hello"}} | Remove trailing comma. | JSON |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
void compute();
int main(){{compute();}} | void compute(); // prototype
int main(){{compute();}} | Declare before use. | C++ |
lambda x: x+1 | lambda x: x+1 | Correct lambda. | Python |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
cin >> x; | int x;
cin >> x; | Declare variable. | C++ |
if (a = 69) | if (a == 69) | Use ==. | R |
let count = 'message' | let count = "message" | Double quotes. | Swift |
fmt.Println 'world' | fmt.Println('world') | Missing parentheses. | Go |
<input type='text' value='value'> | <input type='text' value='value' name='title'> | Add name attribute. | HTML |
const http = require('http'); http.createServer((req,res) => res.end('message')).listen(56); | const http = require('http'); http.createServer((req,res) => res.end('message')).listen(56); | Correct. | Node.js |
int* p = nullptr; *p=5; | int* p = new int; *p=5; | Allocate memory. | C++ |
for i=1,12 do print(i) end | for i=1,12 do print(i) end | Correct. | Lua |
WHERE email = '69' | WHERE email = 69 | Don't quote integer. | SQL |
class User
def method
end
end | class User
def method
end
end | Correct. | Ruby |
'data' + 21 | 'data' + str(21) | Can't add int to string. | Python |
Post.save(); | Post.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
function compute() {{
return
{{key:'hello'}}
}} | function compute() {{
return {{key:'hello'}};
}} | Return object on same line. | JavaScript |
function test(): void {{ return 82; }} | function test(): number {{ return 82; }} | Return type mismatch. | TypeScript |
$list[91] = 5; | if (isset($list[91])) $list[91] = 5; | Check existence. | PHP |
if (item = 75) | if (item == 75) | Use ==. | Scala |
x <- 5; if (x > 3) print('large') | x <- 5; if (x > 3) print('large') | Correct. | R |
bar | bar() | Add parentheses. | Swift |
def handle(bar):
return bar + 1 | def handle(bar):
return bar + 1 | Correct. | Python |
{{"status":"test" "value":91}} | {{"status":"test", "value":91}} | Add comma. | JSON |
if c > 11
print('message') | if c > 11:
print('message') | Colon missing after if. | Python |
'test' + 49 | 'test' + 49.to_s | Convert int. | Ruby |
else
print('hello') | else:
print('hello') | Colon after else. | Python |
System.out.println('message') | System.out.println('message'); | Add semicolon. | Java |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
UPDATE orders SET id='message' WHERE role=35 | UPDATE orders SET id='message' WHERE role=35; | Add semicolon. | SQL |
let mut num=12; let r1=&mut num; let ref2=&mut num; | let mut num=12; {{ let r1=&mut num; }} let ref2=&mut num; | Only one mutable borrow. | Rust |
arr.forEach(function(y) {{ console.log(y); }}) | arr.forEach((y) => {{ console.log(y); }}) | Arrow functions are cleaner. | JavaScript |
{{'age':7, 'age' 36}} | {{'age':7, 'age':36}} | Colon missing. | Python |
while read line; do echo $line; done < log.txt | while read line; do echo $line; done < log.txt | Correct. | Shell |
cin >> b
cout << b; | cin >> b;
cout << b; | Add semicolon. | C++ |
name: info
age: 3 | name: info
age: 3 | Correct. | YAML |
Write-Host 'value' | Write-Host 'value' | Correct. | PowerShell |
assert y > 4 | assert y > 4 | Correct. | Python |
let str = String::from("message"); let ref=&str; str.push_str("!"); | let mut str = String::from("message"); let ref=&str; println!("{{}}", ref); str.push_str("!"); | Cannot mutate while borrowed. | Rust |
.Item {{ color: green; }} | .Item {{ color: green; }} | Correct. | CSS |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
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 |
var x = 5; x = "hello" | var x = "hello" | Type mismatch. | Swift |
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