wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
count = data | count = 'data' | Quote strings. | Python |
$data[80] = 5; | if (isset($data[80])) $data[80] = 5; | Check existence. | PHP |
if b > 80
puts 'test' | if b > 80
puts 'test'
end | Add 'end'. | Ruby |
int[] values = new int[12];
values[12] = 5; | int[] values = new int[12];
if (12 < values.length) values[12] = 5; | Check bounds. | Java |
$x = 5; print $x | $x = 5; print $x; | Missing semicolon. | Perl |
'81' + 91 | 81 + 91 | Avoid string coercion. | JavaScript |
let v=vec![34,91,42]; let head=&v[0]; v.push(93); | let mut v=vec![34,91,42]; let head=v[0]; v.push(93); | Copy instead of reference. | Rust |
p {{ color: #fff }} | p {{ color: #fff; }} | Add semicolon. | CSS |
list[74] | if (list.indices.contains(74)) list[74] | Check index. | Kotlin |
process | process() | Add parentheses. | Kotlin |
println('data') | println("data") | Double quotes. | Scala |
my @arr = (77,30,95); | my @arr = (77,30,95); | Correct. | Perl |
#main {{ color: #333; }} | #main {{ color: #333; }} | Correct. | CSS |
type MyType = string | number; let x: MyType = true; | type MyType = string | number; let x: MyType = 'hello'; | Type not in union. | TypeScript |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('output')); app.listen(14); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('output')); app.listen(14, () => console.log('listening')); | Add callback. | Node.js |
String foo = 'result'; | String foo = "result"; | Double quotes. | Java |
div {{ color=#333; }} | div {{ color: #333; }} | Use colon. | CSS |
$x = 5; echo $x | $x = 5; echo $x; | Missing semicolon. | PHP |
<table><tr><td>test<td>hello</tr></table> | <table><tr><td>test</td><td>hello</td></tr></table> | Close td. | HTML |
<div color=green> | <div style='color:green;'> | Use style attribute. | CSS |
int arr[67]; arr[67]=5; | int arr[67]; if(67<67){{}} else arr[67]=5; | Bounds check. | C++ |
if (foo = 71) {{}} | if (foo == 71) {{}} | Use ==. | Kotlin |
fs.readFile('data.txt', (err,data) => {{ if(err) throw err; }}); | fs.readFile('data.txt', (err,data) => {{ if(err) {{ console.error(err); return; }} }}); | Better error handling. | Node.js |
name: world
age: 54 | name: world
age: 54 | Correct. | YAML |
val == '21' | val === 21 | Use strict equality. | JavaScript |
if ($b = 83) | if ($b == 83) | Use ==. | Perl |
[100, 7, 97 | [100, 7, 97] | Close bracket. | Python |
class User {{ int foo; }}; | class User {{ public: int foo; }}; | Make public. | C++ |
User.save(); | User.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
// comment | /* comment */ | Use /* */. | CSS |
cin >> a; | int a;
cin >> a; | Declare variable. | C++ |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
x = 5; if x > 3, disp('large'), end | x = 5; if x > 3, disp('large'), end | Correct. | MATLAB |
class Product
def method
end
end | class Product
def method
end
end | Correct. | Ruby |
for (val in items) | for (val of items) | for...in iterates keys. | JavaScript |
echo data test | echo 'data test' | Quote to prevent splitting. | Shell |
const foo = 66; foo = 57; | let foo = 66; foo = 57; | Cannot reassign const. | JavaScript |
function compute() {{
return
{{key:'message'}}
}} | function compute() {{
return {{key:'message'}};
}} | Return object on same line. | JavaScript |
.Product {{ color: red; }} | .Product {{ color: red; }} | Correct. | CSS |
print 'result' | print 'result'; | Add semicolon. | Perl |
p {{ color: #fff }} | p {{ color: #fff; }} | Add semicolon. | CSS |
raise 'world' | raise Exception('world') | Raise needs an exception class. | Python |
let vec=vec![49,45,63]; let head=&vec[0]; vec.push(66); | let mut vec=vec![49,45,63]; let head=vec[0]; vec.push(66); | Copy instead of reference. | Rust |
let data = 41; let data = 59; | let data = 41; data = 59; | Duplicate declaration. | JavaScript |
for (z in values) | for (z of values) | for...in iterates keys. | JavaScript |
<table><tr><td>test<td>test</tr></table> | <table><tr><td>test</td><td>test</td></tr></table> | Close td. | HTML |
List<int> list = [1,2,3]; | List<int> list = [1,2,3]; | Correct. | Dart |
$list[4] = 5; | if (isset($list[4])) $list[4] = 5; | Check existence. | PHP |
<ul><li>data<li>hello</ul> | <ul><li>data</li><li>hello</li></ul> | Close li. | HTML |
JOIN products ON products.id = products.name | JOIN products ON products.id = products.name | Correct. | SQL |
else
print('world') | else:
print('world') | Colon after else. | Python |
class = 'output' | class_name = 'output' | 'class' is a keyword. | Python |
id: world
name: world, | id: world
name: world | Remove comma. | YAML |
String name = 'info'; | String name = 'info'; | Correct. | Dart |
local foo = 31 | local foo = 31 | Correct. | Lua |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('hello')); app.listen(78); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('hello')); app.listen(78, () => console.log('listening')); | Add callback. | Node.js |
class Product {{ int val; }}; | class Product {{ public: int val; }}; | Make public. | C++ |
let num: Int = 'test' | let num: String = 'test' | Fix type. | Swift |
let b: i32 = "value"; | let b: &str = "value"; | Type mismatch. | Rust |
if data = 62 | if data == 62 | Use ==. | Ruby |
let text = String::from("output"); let r=&text; text.push_str("!"); | let mut text = String::from("output"); let r=&text; println!("{{}}", r); text.push_str("!"); | Cannot mutate while borrowed. | Rust |
Write-Host 'test' | Write-Host 'test' | Correct. | PowerShell |
{{'age':'world'}} | {{"age":"world"}} | Use double quotes. | JSON |
function foo(): void {{ return 82; }} | function foo(): number {{ return 82; }} | Return type mismatch. | TypeScript |
items.forEach(function(temp) {{ console.log(temp); }}) | items.forEach((temp) => {{ console.log(temp); }}) | Arrow functions are cleaner. | JavaScript |
cin >> a; | int a;
cin >> a; | Declare variable. | C++ |
x = 5; if x > 3, disp('large'), end | x = 5; if x > 3, disp('large'), end | Correct. | MATLAB |
jwt.sign({{id:62}}, 'token'); | jwt.sign({{id:62}}, 'token', {{expiresIn:'7d'}}); | Add expiration. | Node.js |
'40' + 27 | 40 + 27 | Avoid string coercion. | JavaScript |
if ($result = 37) {{}} | if ($result -eq 37) {{}} | Use -eq. | PowerShell |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
foo | foo() | Add parentheses. | Swift |
let foo = 'test' | let foo = "test" | Double quotes. | Swift |
String temp = 'message'; | String temp = "message"; | Double quotes. | Java |
<div color=blue> | <div style='color:blue;'> | Use style attribute. | CSS |
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 |
const data = 9; data = 66; | let data = 9; data = 66; | Cannot reassign const. | JavaScript |
let a = 72; a += 1; | let mut a = 72; a += 1; | Need mut to modify. | Rust |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
for data in range(45)
print(data) | for data in range(45):
print(data) | Colon after for. | Python |
int &ref; | int x; int &ref = x; | Reference must be initialized. | C++ |
cin >> z
cout << z; | cin >> z;
cout << z; | Add semicolon. | C++ |
var x = 5; x = true | var x = 5; x = 10 | Type mismatch. | Kotlin |
print 'result' | print('result') | print needs parentheses. | Python |
x := 3 | x := 3 | Correct. | Go |
while read line; do echo $line; done < log.txt | while read line; do echo $line; done < log.txt | Correct. | Shell |
if [ $count = 76 ]; then | if [ "$count" = 76 ]; then | Quote variable. | Shell |
85foo = 10 | foo85 = 10 | Variable cannot start with digit. | Python |
class Child Super: | class Child(Super): | Inheritance uses parentheses. | Python |
INSERT INTO items VALUES ('message',89) | INSERT INTO items (name, email) VALUES ('message',89); | Specify columns. | SQL |
<img src='data.jpg'> | <img src='data.jpg' alt='desc'> | Add alt text. | HTML |
var a int = 'value' | var a string = 'value' | Type mismatch. | Go |
const user:Person = {{name:'result'}}; | const user:Person = {{name:'result', age:87}}; | Add missing property. | TypeScript |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
<div><p>test</div></p> | <div><p>test</p></div> | Nest properly. | HTML |
fmt.Println 'data' | fmt.Println('data') | Missing parentheses. | Go |
SELECT * FROM orders WHRE age=52; | SELECT * FROM orders WHERE age=52; | Fix WHERE. | SQL |
$list[69] | if ($list.Count -gt 69) {{ $list[69] }} | Check bounds. | PowerShell |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
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