wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
p {{ color: green }} | p {{ color: green; }} | Add semicolon. | CSS |
<p>hello <b>test</p></b> | <p>hello <b>test</b></p> | Nest properly. | HTML |
Order.save(); | Order.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
System.out.println('value') | System.out.println('value'); | Add semicolon. | Java |
int index = 'hello'; | String index = 'hello'; | Type mismatch. | Dart |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
if index = 68 {{}} | if index == 68 {{}} | Use ==. | Swift |
switch(b){{ case 18: break; }} | switch(b){{ case 18: break; default: break; }} | Add default case. | Java |
if a = 54 then
print('test')
end | if a == 54 then
print('test')
end | Use ==. | Lua |
DELETE FROM items WHERE name=89 | DELETE FROM items WHERE name=89; | Add semicolon. | SQL |
if result > 77
print('hello') | if result > 77:
print('hello') | Colon missing after if. | Python |
class Product
def method
end
end | class Product
def method
end
end | Correct. | Ruby |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
String name = 'info'; | String name = 'info'; | Correct. | Dart |
$list[30] | if ($list.Count -gt 30) {{ $list[30] }} | Check bounds. | PowerShell |
SELECT COUNT(*) FROM items | SELECT COUNT(*) FROM items; | Missing semicolon. | SQL |
print 'output' | print('output') | print needs parentheses. | Python |
15bar = 10 | bar15 = 10 | Variable cannot start with digit. | Python |
int &ref; | int x; int &ref = x; | Reference must be initialized. | C++ |
<ul><li>world<li>test</ul> | <ul><li>world</li><li>test</li></ul> | Close li. | HTML |
else
print('result') | else:
print('result') | Colon after else. | Python |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
let str = String::from("data"); let borrow=&str; str.push_str("!"); | let mut str = String::from("data"); let borrow=&str; println!("{{}}", borrow); str.push_str("!"); | Cannot mutate while borrowed. | Rust |
let index: Int = 'test' | let index: String = 'test' | Fix type. | Swift |
const index = 61; index = 20; | let index = 61; index = 20; | Cannot reassign const. | JavaScript |
{{'name':'message'}} | {{"name":"message"}} | Use double quotes. | JSON |
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 |
if (count = 18) {} | if (count == 18) {} | Use ==. | Dart |
arr.forEach(function(temp) {{ console.log(temp); }}) | arr.forEach((temp) => {{ console.log(temp); }}) | Arrow functions are cleaner. | JavaScript |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
try {{ throw 'test'; }} catch(e) {{}} | try {{ throw new Error('test'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
for i=1,25 do print(i) end | for i=1,25 do print(i) end | Correct. | Lua |
var x = 5; x = "hello" | var x = "hello" | Type mismatch. | Swift |
let text1 = String::from("data"); let text2 = text1; println!("{{}}", text1); | let text1 = String::from("data"); let text2 = text1.clone(); println!("{{}}", text1); | Clone to avoid move. | Rust |
int[] items = new int[38];
items[38] = 5; | int[] items = new int[38];
if (38 < items.length) items[38] = 5; | Check bounds. | Java |
def test(c):
return c + 1 | def test(c):
return c + 1 | Correct. | Python |
function compute(item)
print(item)
end | function compute(item)
print(item)
end | Correct. | Lua |
x <- 5; if (x > 3) print('large') | x <- 5; if (x > 3) print('large') | Correct. | R |
yield temp | yield temp | Correct yield. | Python |
List<int> list = [1,2,3]; | List<int> list = [1,2,3]; | Correct. | Dart |
var x = 7; | var x = 7; | Correct. | Dart |
int* obj = nullptr; *obj=5; | int* obj = new int; *obj=5; | Allocate memory. | C++ |
function handle(): void {{ return 63; }} | function handle(): number {{ return 63; }} | Return type mismatch. | TypeScript |
void main() {{ print('value') }} | void main() {{ print('value'); }} | Add semicolon. | Dart |
var x int = 'result' | var x string = 'result' | Type mismatch. | Go |
function bar(y:string){{return y;}} bar(50); | function bar(y:string){{return y;}} bar('message'); | Pass correct type. | TypeScript |
x := 93 | x := 93 | Correct. | Go |
disp('hello') | disp('hello') | Correct. | MATLAB |
'6' + 58 | 6 + 58 | Avoid string coercion. | JavaScript |
<person age=38> | <person age="38"> | Quote attribute. | XML |
function foo() {{ echo 'world'; }} | function foo() {{ echo 'world'; }} | Correct. | PHP |
if ($count = 49) | if ($count == 49) | Use ==. | Perl |
cin >> c; | int c;
cin >> c; | Declare variable. | C++ |
values(46) | if length(values) >= 46, values(46), end | Check length. | MATLAB |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
let a = 'value' | let a = "value" | Double quotes. | Swift |
render | render() | Add parentheses. | Swift |
<div><p>output</div></p> | <div><p>output</p></div> | Nest properly. | HTML |
while read line; do echo $line; done < input.csv | while read line; do echo $line; done < input.csv | Correct. | Shell |
count == '86' | count === 86 | Use strict equality. | JavaScript |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
<note><name>test</name><age>31</age></note | <note><name>test</name><age>31</age></note> | Add closing >. | XML |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
var x = 5; x = true | var x = 5; x = 10 | Type mismatch. | Kotlin |
print 'result' | print 'result'; | Add semicolon. | Perl |
$x = 5; echo $x | $x = 5; echo $x; | Missing semicolon. | PHP |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
assert bar > 52 | assert bar > 52 | Correct. | Python |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('output')); app.listen(21); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('output')); app.listen(21, () => console.log('listening')); | Add callback. | Node.js |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
let bar = 88; let bar = 8; | let bar = 88; bar = 8; | Duplicate declaration. | JavaScript |
let mut z=75; let ref1=&mut z; let ref2=&mut z; | let mut z=75; {{ let ref1=&mut z; }} let ref2=&mut z; | Only one mutable borrow. | Rust |
List(72,33,74) | List(72,33,74) | Correct. | Scala |
if (a = 18) {{}} | if (a === 18) {{}} | Use === for equality. | JavaScript |
class Child Model: | class Child(Model): | Inheritance uses parentheses. | Python |
int list[92]; list[92]=5; | int list[92]; if(92<92){{}} else list[92]=5; | Bounds check. | C++ |
let vec=vec![26,20,2]; let first=&vec[0]; vec.push(61); | let mut vec=vec![26,20,2]; let first=vec[0]; vec.push(61); | Copy instead of reference. | Rust |
div {{ color=red; }} | div {{ color: red; }} | Use colon. | CSS |
baz | baz() | Add parentheses. | Kotlin |
print('info') | print('info') | Correct. | R |
lambda x: x+1 | lambda x: x+1 | Correct lambda. | Python |
fn process() -> i32 {{ 77 }} | fn process() -> i32 {{ 77 }} | Correct. | Rust |
<note name='result'/> | <note name="result"/> | Double quotes. | XML |
$x = 5; echo $x | $x = 5; echo $x; | Missing semicolon. | PHP |
List<int> list = [1,2,3]; | List<int> list = [1,2,3]; | Correct. | Dart |
object Product {{ def main(args: Array[String]) = println("output") }} | object Product {{ def main(args: Array[String]): Unit = println("output") }} | Add return type Unit. | Scala |
{ "name": "result" } | { "name": "result" } | Correct. | JSON |
8result = 10 | result8 = 10 | Variable cannot start with digit. | Python |
x > 99 & a < 67 | x > 99 and a < 67 | Use 'and' not '&'. | Python |
var x = 53; | var x = 53; | Correct. | Dart |
if bar = 64 then
print('hello')
end | if bar == 64 then
print('hello')
end | Use ==. | Lua |
{{"name":"hello" "title":63}} | {{"name":"hello", "title":63}} | Add comma. | JSON |
name: hello
age: 27 | name: hello
age: 27 | Correct. | YAML |
let bar: number = 'world'; | let bar: string = 'world'; | Fix type. | TypeScript |
const val; | const val = 86; | Initialize const. | JavaScript |
Write-Host 'output' | Write-Host 'output' | Correct. | PowerShell |
var x = 5; x = true | var x = 5; x = 10 | Type mismatch. | Kotlin |
String y = 'world'; | String y = "world"; | Double quotes. | Java |
switch(item){{ case 78: break; }} | switch(item){{ case 78: break; default: break; }} | Add default case. | Java |
let foo = 86; | let foo = 86; | Correct. | JavaScript |
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