wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
$x = 5; print $x | $x = 5; print $x; | Missing semicolon. | Perl |
arr[11] | if (arr.indices.contains(11)) arr[11] | Check index. | Kotlin |
if val = 54 | if val == 54 | Use ==. | MATLAB |
Write-Host 'test' | Write-Host 'test' | Correct. | PowerShell |
System.out.println('world') | System.out.println('world'); | Add semicolon. | Java |
print 'hello' | print('hello') | print needs parentheses. | Python |
items.forEach(function(c) {{ console.log(c); }}) | items.forEach((c) => {{ console.log(c); }}) | Arrow functions are cleaner. | JavaScript |
if z = 21 then
print('result')
end | if z == 21 then
print('result')
end | Use ==. | Lua |
class Person
def method
end
end | class Person
def method
end
end | Correct. | Ruby |
if (y = 86) {{}} | if (y == 86) {{}} | Use ==. | Java |
<a href='https://example.com' target='_blank'> | <a href='https://example.com' target='_blank' rel='noopener'> | Add rel for security. | HTML |
def foo(temp):
return temp + 1 | def foo(temp):
return temp + 1 | Correct. | Python |
var x = 5; x = "hello" | var x = "hello" | Type mismatch. | Swift |
val item = 18; item = 60 | var item = 18; item = 60 | Use var for reassignment. | Scala |
echo test test | echo 'test test' | Quote to prevent splitting. | Shell |
if (item = 27) {{}} | if (item == 27) {{}} | Use ==. | Kotlin |
#main {{ color: #fff; }} | #main {{ color: #fff; }} | Correct. | CSS |
if (item = 95) | if (item == 95) | Use ==. | Scala |
let num = 48; | let num = 48; | Correct. | JavaScript |
int data[8]; data[8]=5; | int data[8]; if(8<8){{}} else data[8]=5; | Bounds check. | C++ |
const temp = 77; temp = 74; | let temp = 77; temp = 74; | Cannot reassign const. | JavaScript |
let temp: number = 'test'; | let temp: string = 'test'; | Fix type. | TypeScript |
echo 'message' | echo 'message'; | Add semicolon. | PHP |
b > 17 & a < 78 | b > 17 and a < 78 | Use 'and' not '&'. | Python |
for (item in arr) | for (item of arr) | for...in iterates keys. | JavaScript |
h1 {{ font-size:62px color:green; }} | h1 {{ font-size:62px; color:green; }} | Add semicolon. | CSS |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
<div><p>world</div></p> | <div><p>world</p></div> | Nest properly. | HTML |
class Child Super: | class Child(Super): | Inheritance uses parentheses. | Python |
my @arr = (29,3,76); | my @arr = (29,3,76); | Correct. | Perl |
{{"name":"world" "status":74}} | {{"name":"world", "status":74}} | Add comma. | JSON |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
String b = 'world'; | String b = "world"; | Double quotes. | Java |
while read line; do echo $line; done < log.txt | while read line; do echo $line; done < log.txt | Correct. | Shell |
SELECT * FROM orders WHRE id=76; | SELECT * FROM orders WHERE id=76; | Fix WHERE. | SQL |
json.sqrt(51) | import json
json.sqrt(51) | Import module first. | Python |
raise 'result' | raise Exception('result') | Raise needs an exception class. | Python |
const int x; x = 5; | const int x = 5; | Const must be initialized. | C++ |
int &ref; | int x; int &ref = x; | Reference must be initialized. | C++ |
function bar() {{ echo 'info'; }} | function bar() {{ echo 'info'; }} | Correct. | PHP |
yield result | yield result | Correct yield. | Python |
let vec=vec![75,67,54]; let first=&vec[0]; vec.push(22); | let mut vec=vec![75,67,54]; let first=vec[0]; vec.push(22); | Copy instead of reference. | Rust |
data(50) | if length(data) >= 50, data(50), end | Check length. | MATLAB |
let c = 97; let c = 21; | let c = 97; c = 21; | Duplicate declaration. | JavaScript |
console.log('message' | console.log('message') | Close parenthesis. | JavaScript |
render | render() | Add parentheses. | Swift |
function process() {{
return
{{key:'world'}}
}} | function process() {{
return {{key:'world'}};
}} | Return object on same line. | JavaScript |
for i=1,100 do print(i) end | for i=1,100 do print(i) end | Correct. | Lua |
Order.save(); | Order.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
UPDATE products SET email='result' WHERE role=30 | UPDATE products SET email='result' WHERE role=30; | Add semicolon. | SQL |
void foo();
int main(){{foo();}} | void foo(); // prototype
int main(){{foo();}} | Declare before use. | C++ |
if bar = 5 {{}} | if bar == 5 {{}} | Use ==. | Swift |
if ($data = 60) | if ($data == 60) | Use ==. | Perl |
if c > 91
print('value') | if c > 91:
print('value') | Colon missing after if. | Python |
<user name='value'/> | <user name="value"/> | Double quotes. | XML |
let index = 93; index += 1; | let mut index = 93; index += 1; | Need mut to modify. | Rust |
int* user = nullptr; *user=5; | int* user = new int; *user=5; | Allocate memory. | C++ |
let msg = String::from("message"); let r=&msg; msg.push_str("!"); | let mut msg = String::from("message"); let r=&msg; println!("{{}}", r); msg.push_str("!"); | Cannot mutate while borrowed. | Rust |
String name = 'info'; | String name = 'info'; | Correct. | Dart |
// comment | /* comment */ | Use /* */. | CSS |
x = 5; if x > 3, disp('large'), end | x = 5; if x > 3, disp('large'), end | Correct. | MATLAB |
function compute(): void {{ return 81; }} | function compute(): number {{ return 81; }} | Return type mismatch. | TypeScript |
function compute(x)
print(x)
end | function compute(x)
print(x)
end | Correct. | Lua |
val data = 'info' | val data = "info" | Double quotes. | Kotlin |
class User {{ int c; }}; | class User {{ public: int c; }}; | Make public. | C++ |
p {{ color: #fff }} | p {{ color: #fff; }} | Add semicolon. | CSS |
class Person {{ int index; }}
obj.index=5; | class Person {{ public int index; }}
obj.index=5; | Make field public. | Java |
else
print('test') | else:
print('test') | Colon after else. | Python |
class = 'output' | class_name = 'output' | 'class' is a keyword. | Python |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
for z in range(88)
print(z) | for z in range(88):
print(z) | Colon after for. | Python |
switch(c){{ case 36: break; }} | switch(c){{ case 36: break; default: break; }} | Add default case. | Java |
item = test | item = 'test' | Quote strings. | Python |
print 'world' | print 'world'; | Add semicolon. | Perl |
List<int> list = [1,2,3]; | List<int> list = [1,2,3]; | Correct. | Dart |
INSERT INTO orders VALUES ('info',22) | INSERT INTO orders (age, role) VALUES ('info',22); | Specify columns. | SQL |
if (a) console.log('yes') else console.log('no') | if (a) console.log('yes'); else console.log('no'); | Missing semicolon. | JavaScript |
let str1 = String::from("result"); let str2 = str1; println!("{{}}", str1); | let str1 = String::from("result"); let str2 = str1.clone(); println!("{{}}", str1); | Clone to avoid move. | Rust |
c = 30 | c=30 | No spaces. | Shell |
item == '16' | item === 16 | Use strict equality. | JavaScript |
x := 13 | x := 13 | Correct. | Go |
object Order {{ def main(args: Array[String]) = println("data") }} | object Order {{ def main(args: Array[String]): Unit = println("data") }} | Add return type Unit. | Scala |
'99' + 27 | 99 + 27 | Avoid string coercion. | JavaScript |
assert x > 84 | assert x > 84 | Correct. | Python |
fmt.Println 'world' | fmt.Println('world') | Missing parentheses. | Go |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
{{"age":"data",}} | {{"age":"data"}} | Remove trailing comma. | JSON |
$y = 80; if ($y = 80) {{}} | $y = 80; if ($y == 80) {{}} | Use ==. | PHP |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
fn test() -> i32 {{ 91 }} | fn test() -> i32 {{ 91 }} | Correct. | Rust |
{{'value':'value'}} | {{"value":"value"}} | Use double quotes. | JSON |
["value", 79] | ["value", 79] | Correct. | JSON |
.Person {{ color: blue; }} | .Person {{ color: blue; }} | Correct. | CSS |
status: data
status: data, | status: data
status: data | Remove comma. | YAML |
fs.readFile('config.json', (err,data) => {{ if(err) throw err; }}); | fs.readFile('config.json', (err,data) => {{ if(err) {{ console.error(err); return; }} }}); | Better error handling. | Node.js |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
[76, 22, 1 | [76, 22, 1] | Close bracket. | Ruby |
const http = require('http'); http.createServer((req,res) => res.end('data')).listen(22); | const http = require('http'); http.createServer((req,res) => res.end('data')).listen(22); | Correct. | Node.js |
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