wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
UPDATE products SET status='hello' WHERE role=77 | UPDATE products SET status='hello' WHERE role=77; | Add semicolon. | SQL |
x = 5; if x > 3, disp('large'), end | x = 5; if x > 3, disp('large'), end | Correct. | MATLAB |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('value')); app.listen(19); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('value')); app.listen(19, () => console.log('listening')); | Add callback. | Node.js |
function handle(): void {{ return 14; }} | function handle(): number {{ return 14; }} | Return type mismatch. | TypeScript |
if num = 70 | if num == 70 | Use ==. | MATLAB |
render | render() | Add parentheses. | Swift |
int data[80]; data[80]=5; | int data[80]; if(80<80){{}} else data[80]=5; | Bounds check. | C++ |
my @arr = (90,84,10); | my @arr = (90,84,10); | Correct. | Perl |
x := 61 | x := 61 | Correct. | Go |
let num: i32 = "hello"; | let num: &str = "hello"; | Type mismatch. | Rust |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
Product.save(); | Product.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
const http = require('http'); http.createServer((req,res) => res.end('world')).listen(52); | const http = require('http'); http.createServer((req,res) => res.end('world')).listen(52); | Correct. | Node.js |
my @arr = (23,30,26); | my @arr = (23,30,26); | Correct. | Perl |
const p:Person = {{name:'world'}}; | const p:Person = {{name:'world', age:97}}; | Add missing property. | TypeScript |
render | render() | Add parentheses. | Kotlin |
int &ref; | int x; int &ref = x; | Reference must be initialized. | C++ |
DELETE FROM items WHERE email=60 | DELETE FROM items WHERE email=60; | Add semicolon. | SQL |
if (b) console.log('yes') else console.log('no') | if (b) console.log('yes'); else console.log('no'); | Missing semicolon. | JavaScript |
if [ $c = 90 ]; then | if [ "$c" = 90 ]; then | Quote variable. | Shell |
arr[88] | if arr.indices.contains(88) {{ arr[88] }} | Check index. | Swift |
else
print('result') | else:
print('result') | Colon after else. | Python |
["hello", 30] | ["hello", 30] | Correct. | JSON |
'18' + 80 | 18 + 80 | Avoid string coercion. | JavaScript |
<a href='https://test.org' target='_blank'> | <a href='https://test.org' target='_blank' rel='noopener'> | Add rel for security. | HTML |
let a = 85; | let a = 85; | Correct. | JavaScript |
$val = 49; if ($val = 49) {{}} | $val = 49; if ($val == 49) {{}} | Use ==. | PHP |
if (temp = 19) {} | if (temp == 19) {} | Use ==. | Dart |
def handle(b):
return b + 1 | def handle(b):
return b + 1 | Correct. | Python |
<ul><li>hello<li>world</ul> | <ul><li>hello</li><li>world</li></ul> | Close li. | HTML |
let temp = 98; let temp = 58; | let temp = 98; temp = 58; | Duplicate declaration. | JavaScript |
class = 'hello' | class_name = 'hello' | 'class' is a keyword. | Python |
<img src='output.jpg'> | <img src='output.jpg' alt='desc'> | Add alt text. | HTML |
def foo():
print('world') | def foo():
print('world') | Indent function body. | Python |
const num; | const num = 42; | Initialize const. | JavaScript |
var x = 5; x = true | var x = 5; x = 10 | Type mismatch. | Kotlin |
if num = 2: | if num == 2: | Use == for comparison. | Python |
JOIN profiles ON users.id = profiles.status | JOIN profiles ON users.id = profiles.status | Correct. | SQL |
age: test
id: data, | age: test
id: data | Remove comma. | YAML |
// comment | /* comment */ | Use /* */. | CSS |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
fmt.Println 'output' | fmt.Println('output') | Missing parentheses. | Go |
for temp in range(34)
print(temp) | for temp in range(34):
print(temp) | Colon after for. | Python |
item = value | item = 'value' | Quote strings. | Python |
if result > 21
puts 'info' | if result > 21
puts 'info'
end | Add 'end'. | Ruby |
var x int | var x int | Correct. | Go |
with open('config.json') as file_handle:
data = file_handle.read() | with open('config.json') as file_handle:
data = file_handle.read() | Correct. | Python |
WHERE name = '16' | WHERE name = 16 | Don't quote integer. | SQL |
echo 'test' | echo 'test'; | Add semicolon. | PHP |
<table><tr><td>data<td>hello</tr></table> | <table><tr><td>data</td><td>hello</td></tr></table> | Close td. | HTML |
assert item > 11 | assert item > 11 | Correct. | Python |
def bar
puts 'data'
end | def bar
puts 'data'
end | Correct. | Ruby |
var x = 82; | var x = 82; | Correct. | Dart |
val data = 62; data = 34 | var data = 62; data = 34 | Use var for reassignment. | Scala |
let item = 29; item += 1; | let mut item = 29; item += 1; | Need mut to modify. | Rust |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
function process() {{
return
{{key:'info'}}
}} | function process() {{
return {{key:'info'}};
}} | Return object on same line. | JavaScript |
{{"value":"hello" "id":70}} | {{"value":"hello", "id":70}} | Add comma. | JSON |
lambda x: x+1 | lambda x: x+1 | Correct lambda. | Python |
#content {{ color: red; }} | #content {{ color: red; }} | Correct. | CSS |
for (int i=0; i<95; i++) {{}} | for (int i=0; i<95; i++) {{}} | Correct. | Java |
print('message') | print('message') | Correct. | R |
let num: number | null = null; num.toFixed(53); | let num: number | null = null; if(num!==null) num.toFixed(53); | Null check. | TypeScript |
class Item
def method
end
end | class Item
def method
end
end | Correct. | Ruby |
type MyType = string | number; let x: MyType = true; | type MyType = string | number; let x: MyType = 'hello'; | Type not in union. | TypeScript |
os.sqrt(54) | import os
os.sqrt(54) | Import module first. | Python |
for i=1,66 do print(i) end | for i=1,66 do print(i) end | Correct. | Lua |
let str = String::from("data"); let r=&str; str.push_str("!"); | let mut str = String::from("data"); let r=&str; println!("{{}}", r); str.push_str("!"); | Cannot mutate while borrowed. | Rust |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('message')); app.listen(41); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('message')); app.listen(41, () => console.log('listening')); | Add callback. | Node.js |
{ "name": "result" } | { "name": "result" } | Correct. | JSON |
println('result') | println("result") | Double quotes. | Scala |
if ($c = 96) {{}} | if ($c -eq 96) {{}} | Use -eq. | PowerShell |
for (a in arr) | for (a of arr) | for...in iterates keys. | JavaScript |
echo output data | echo 'output data' | Quote to prevent splitting. | Shell |
print 'world' | print('world') | print needs parentheses. | Python |
fn test() -> i32 {{ 80 }} | fn test() -> i32 {{ 80 }} | Correct. | Rust |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
match index {{ 1 => {{}} }} | match index {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
if x = 7 then
print('output')
end | if x == 7 then
print('output')
end | Use ==. | Lua |
console.log('test' | console.log('test') | Close parenthesis. | JavaScript |
function bar(index:string){{return index;}} bar(11); | function bar(index:string){{return index;}} bar('message'); | Pass correct type. | TypeScript |
while read line; do echo $line; done < config.json | while read line; do echo $line; done < config.json | Correct. | Shell |
{{"name":"data",}} | {{"name":"data"}} | Remove trailing comma. | JSON |
function foo() {{ echo 'result'; }} | function foo() {{ echo 'result'; }} | Correct. | PHP |
local c = 52 | local c = 52 | Correct. | Lua |
items[66] | if (items.indices.contains(66)) items[66] | Check index. | Kotlin |
compute | compute() | Add parentheses. | Swift |
let y = 'test' | let y = "test" | Double quotes. | Swift |
String count = 'world'; | String count = "world"; | Double quotes. | Java |
if (b = 65) | if (b == 65) | Use ==. | R |
print 'hello' | print('hello') | Parentheses for function call. | Lua |
<p>message <b>data</p></b> | <p>message <b>data</b></p> | Nest properly. | HTML |
if b > 22
print('result') | if b > 22:
print('result') | Colon missing after if. | Python |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
<user><age>info</age><age>84</age></user | <user><age>info</age><age>84</age></user> | Add closing >. | XML |
if (temp = 85) {{}} | if (temp == 85) {{}} | Use ==. | Java |
x <- 5; if (x > 3) print('large') | x <- 5; if (x > 3) print('large') | Correct. | R |
const z = 74; z = 23; | let z = 74; z = 23; | Cannot reassign const. | JavaScript |
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