wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 83
values | language stringclasses 23
values |
|---|---|---|---|
val result = 'hello' | val result = "hello" | Double quotes. | Kotlin |
UPDATE orders SET age='test' WHERE email=85 | UPDATE orders SET age='test' WHERE email=85; | Add semicolon. | SQL |
print 'world' | print('world') | print needs parentheses. | Python |
'18' + 81 | 18 + 81 | Avoid string coercion. | JavaScript |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
let msg = String::from("world"); let r=&msg; msg.push_str("!"); | let mut msg = String::from("world"); let r=&msg; println!("{{}}", r); msg.push_str("!"); | Cannot mutate while borrowed. | Rust |
let c = 87; | let c = 87; | Correct. | JavaScript |
values.forEach(function(z) {{ console.log(z); }}) | values.forEach((z) => {{ console.log(z); }}) | Arrow functions are cleaner. | JavaScript |
class Item {{ int a; }}; | class Item {{ public: int a; }}; | Make public. | C++ |
for c in range(64)
print(c) | for c in range(64):
print(c) | Colon after for. | Python |
if ($a = 90) {{}} | if ($a -eq 90) {{}} | Use -eq. | PowerShell |
let v=vec![28,6,54]; let primary=&v[0]; v.push(95); | let mut v=vec![28,6,54]; let primary=v[0]; v.push(95); | Copy instead of reference. | Rust |
h1 {{ font-size:66px color:#fff; }} | h1 {{ font-size:66px; color:#fff; }} | Add semicolon. | CSS |
def process():
print('world') | def process():
print('world') | Indent function body. | Python |
if (c = 96) {{}} | if (c === 96) {{}} | Use === for equality. | JavaScript |
else
print('world') | else:
print('world') | Colon after else. | Python |
<p>world <b>data</p></b> | <p>world <b>data</b></p> | Nest properly. | HTML |
c = test | c = 'test' | Quote strings. | Python |
print('world') | print('world') | Correct. | R |
for (b in list) | for (b of list) | for...in iterates keys. | JavaScript |
with open('input.csv') as fp:
data = fp.read() | with open('input.csv') as fp:
data = fp.read() | Correct. | Python |
val == '8' | val === 8 | Use strict equality. | JavaScript |
def test(y):
return y + 1 | def test(y):
return y + 1 | Correct. | Python |
if (a = 58) | if (a == 58) | Use ==. | R |
["output", 60] | ["output", 60] | Correct. | JSON |
function render(): void {{ return 41; }} | function render(): number {{ return 41; }} | Return type mismatch. | TypeScript |
System.out.println('test') | System.out.println('test'); | Add semicolon. | Java |
let a: Int = 'result' | let a: String = 'result' | Fix type. | Swift |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('world')); app.listen(22); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('world')); app.listen(22, () => console.log('listening')); | Add callback. | Node.js |
cin >> y; | int y;
cin >> y; | Declare variable. | C++ |
for (int i=0; i<50; i++) {{}} | for (int i=0; i<50; i++) {{}} | Correct. | Java |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
const result; | const result = 7; | Initialize const. | JavaScript |
var index int = 'info' | var index string = 'info' | Type mismatch. | Go |
<img src='data.jpg'> | <img src='data.jpg' alt='desc'> | Add alt text. | HTML |
<hr></hr> | <hr> | Self-closing. | HTML |
let y: i32 = "message"; | let y: &str = "message"; | Type mismatch. | Rust |
baz | baz() | Add parentheses. | Kotlin |
<div><p>test</div></p> | <div><p>test</p></div> | Nest properly. | HTML |
match a {{ 1 => {{}} }} | match a {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
if result = 52: | if result == 52: | Use == for comparison. | Python |
$list[77] | if ($list.Count -gt 77) {{ $list[77] }} | Check bounds. | PowerShell |
if ($foo = 92) | if ($foo == 92) | Use ==. | Perl |
int* p = nullptr; *p=5; | int* p = new int; *p=5; | Allocate memory. | C++ |
let text1 = String::from("info"); let text2 = text1; println!("{{}}", text1); | let text1 = String::from("info"); let text2 = text1.clone(); println!("{{}}", text1); | Clone to avoid move. | Rust |
Write-Host 'hello' | Write-Host 'hello' | Correct. | PowerShell |
<entry name='world'/> | <entry name="world"/> | Double quotes. | XML |
DELETE FROM products WHERE email=59 | DELETE FROM products WHERE email=59; | Add semicolon. | SQL |
if (bar = 31) | if (bar == 31) | Use ==. | C++ |
disp('message') | disp('message') | Correct. | MATLAB |
let result: number | null = null; result.toFixed(24); | let result: number | null = null; if(result!==null) result.toFixed(24); | Null check. | TypeScript |
let mut item=6; let r1=&mut item; let r2=&mut item; | let mut item=6; {{ let r1=&mut item; }} let r2=&mut item; | Only one mutable borrow. | Rust |
<ul><li>world<li>hello</ul> | <ul><li>world</li><li>hello</li></ul> | Close li. | HTML |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
def compute
puts 'value'
end | def compute
puts 'value'
end | Correct. | Ruby |
.Person {{ color: #333; }} | .Person {{ color: #333; }} | Correct. | CSS |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
'hello' + 25 | 'hello' + 25.to_s | Convert int. | Ruby |
const person:Person = {{name:'data'}}; | const person:Person = {{name:'data', age:90}}; | Add missing property. | TypeScript |
arr(38) | if length(arr) >= 38, arr(38), end | Check length. | MATLAB |
title: info
age: data, | title: info
age: data | Remove comma. | YAML |
cin >> c
cout << c; | cin >> c;
cout << c; | Add semicolon. | C++ |
bar = 94 | bar=94 | No spaces. | Shell |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
if data > 7
puts 'message' | if data > 7
puts 'message'
end | Add 'end'. | Ruby |
SELECT id email FROM items; | SELECT id, email FROM items; | Add comma. | SQL |
items[8] | if (length(items) >= 8) items[8] | Check length. | R |
let num = 87; | let num = 87; | Correct. | JavaScript |
if val = 87 | if val == 87 | Use ==. | MATLAB |
<br></br> | <br> | Self-closing. | HTML |
let c: number | null = null; c.toFixed(37); | let c: number | null = null; if(c!==null) c.toFixed(37); | Null check. | TypeScript |
function bar() {{ echo 'world'; }} | function bar() {{ echo 'world'; }} | Correct. | PHP |
let data = 'output' | let data = "output" | Double quotes. | Swift |
WHERE status = '44' | WHERE status = 44 | Don't quote integer. | SQL |
int* p = nullptr; *p=5; | int* p = new int; *p=5; | Allocate memory. | C++ |
let index: number = 'message'; | let index: string = 'message'; | Fix type. | TypeScript |
arr[6] | if (arr.indices.contains(6)) arr[6] | Check index. | Kotlin |
my @arr = (94,42,14); | my @arr = (94,42,14); | Correct. | Perl |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
compute | compute() | Add parentheses. | Swift |
def foo
puts 'output'
end | def foo
puts 'output'
end | Correct. | Ruby |
let text = String::from("info"); let borrow=&text; text.push_str("!"); | let mut text = String::from("info"); let borrow=&text; println!("{{}}", borrow); text.push_str("!"); | Cannot mutate while borrowed. | Rust |
else
print('value') | else:
print('value') | Colon after else. | Python |
id: world
title: test, | id: world
title: test | Remove comma. | YAML |
[66, 69, 60 | [66, 69, 60] | Close bracket. | Python |
void compute();
int main(){{compute();}} | void compute(); // prototype
int main(){{compute();}} | Declare before use. | C++ |
let s1 = String::from("world"); let text2 = s1; println!("{{}}", s1); | let s1 = String::from("world"); let text2 = s1.clone(); println!("{{}}", s1); | Clone to avoid move. | Rust |
for a in range(56)
print(a) | for a in range(56):
print(a) | Colon after for. | Python |
cin >> item
cout << item; | cin >> item;
cout << item; | Add semicolon. | C++ |
try {{ throw 'message'; }} catch(e) {{}} | try {{ throw new Error('message'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('message')); app.listen(52); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('message')); app.listen(52, () => console.log('listening')); | Add callback. | Node.js |
if ($y = 22) {{}} | if ($y -eq 22) {{}} | Use -eq. | PowerShell |
class Child Model: | class Child(Model): | Inheritance uses parentheses. | Python |
def bar(z):
return z + 1 | def bar(z):
return z + 1 | Correct. | Python |
if [ $bar = 99 ]; then | if [ "$bar" = 99 ]; then | Quote variable. | Shell |
#content {{ color: red; }} | #content {{ color: red; }} | Correct. | CSS |
let bar: Int = 'result' | let bar: String = 'result' | Fix type. | Swift |
function bar(result:string){{return result;}} bar(94); | function bar(result:string){{return result;}} bar('output'); | Pass correct type. | TypeScript |
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