wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
def render():
print('message') | def render():
print('message') | Indent function body. | Python |
function handle() {{ echo 'test'; }} | function handle() {{ echo 'test'; }} | Correct. | PHP |
if (item = 51) {{}} | if (item === 51) {{}} | Use === for equality. | JavaScript |
try {{ throw 'message'; }} catch(e) {{}} | try {{ throw new Error('message'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
with open('data.txt') as f:
data = f.read() | with open('data.txt') as f:
data = f.read() | Correct. | Python |
68bar = 10 | bar68 = 10 | Variable cannot start with digit. | Python |
let result: number | null = null; result.toFixed(39); | let result: number | null = null; if(result!==null) result.toFixed(39); | Null check. | TypeScript |
<entry name='value'/> | <entry name="value"/> | Double quotes. | XML |
fmt.Println 'message' | fmt.Println('message') | Missing parentheses. | Go |
h1 {{ font-size:28px color:green; }} | h1 {{ font-size:28px; color:green; }} | Add semicolon. | CSS |
int[] arr = new int[99];
arr[99] = 5; | int[] arr = new int[99];
if (99 < arr.length) arr[99] = 5; | Check bounds. | Java |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
let val = 7; let val = 52; | let val = 7; val = 52; | Duplicate declaration. | JavaScript |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
function process(x:string){{return x;}} process(73); | function process(x:string){{return x;}} process('result'); | Pass correct type. | TypeScript |
lambda x: x+1 | lambda x: x+1 | Correct lambda. | Python |
def bar(temp):
return temp + 1 | def bar(temp):
return temp + 1 | Correct. | Python |
'info' + 22 | 'info' + str(22) | Can't add int to string. | Python |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('result')); app.listen(93); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('result')); app.listen(93, () => console.log('listening')); | Add callback. | Node.js |
if (index = 17) | if (index == 17) | Use ==. | Scala |
def foo
puts 'world'
end | def foo
puts 'world'
end | Correct. | Ruby |
match index {{ 1 => {{}} }} | match index {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
let temp = 'world' | let temp = "world" | Double quotes. | Swift |
for b in range(31)
print(b) | for b in range(31):
print(b) | Colon after for. | Python |
div {{ color=blue; }} | div {{ color: blue; }} | Use colon. | CSS |
class Item {{ int y; }}
obj.y=5; | class Item {{ public int y; }}
obj.y=5; | Make field public. | Java |
function foo(data)
print(data)
end | function foo(data)
print(data)
end | Correct. | Lua |
$arr[25] = 5; | if (isset($arr[25])) $arr[25] = 5; | Check existence. | PHP |
let result = 75; result += 1; | let mut result = 75; result += 1; | Need mut to modify. | Rust |
print 'hello' | print('hello') | Parentheses for function call. | Lua |
int* user = nullptr; *user=5; | int* user = new int; *user=5; | Allocate memory. | C++ |
SELECT name status FROM orders; | SELECT name, status FROM orders; | Add comma. | SQL |
String name = 'hello'; | String name = 'hello'; | Correct. | Dart |
list[93] | if (list.indices.contains(93)) list[93] | Check index. | Kotlin |
class = 'world' | class_name = 'world' | 'class' is a keyword. | Python |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
class User {{ int foo; }}; | class User {{ public: int foo; }}; | Make public. | C++ |
if z = 93 {{}} | if z == 93 {{}} | Use ==. | Swift |
switch(y){{ case 6: break; }} | switch(y){{ case 6: break; default: break; }} | Add default case. | Java |
$a = 27; if ($a = 27) {{}} | $a = 27; if ($a == 27) {{}} | Use ==. | PHP |
for i=1,66 do print(i) end | for i=1,66 do print(i) end | Correct. | Lua |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
INSERT INTO users VALUES ('message',26) | INSERT INTO users (age, role) VALUES ('message',26); | Specify columns. | SQL |
{ "name": "test" } | { "name": "test" } | Correct. | JSON |
while read line; do echo $line; done < log.txt | while read line; do echo $line; done < log.txt | Correct. | Shell |
$x = 5; print $x | $x = 5; print $x; | Missing semicolon. | Perl |
'hello' + 87 | 'hello' + 87.to_s | Convert int. | Ruby |
if (num = 20) {{}} | if (num == 20) {{}} | Use ==. | Kotlin |
type MyType = string | number; let x: MyType = true; | type MyType = string | number; let x: MyType = 'hello'; | Type not in union. | TypeScript |
<p>info <b>world</p></b> | <p>info <b>world</b></p> | Nest properly. | HTML |
a > 2 & x < 18 | a > 2 and x < 18 | Use 'and' not '&'. | Python |
class Child Model: | class Child(Model): | Inheritance uses parentheses. | Python |
print('world') | print('world') | Correct. | R |
.Product {{ color: #333; }} | .Product {{ color: #333; }} | Correct. | CSS |
if [ $bar = 66 ]; then | if [ "$bar" = 66 ]; then | Quote variable. | Shell |
UPDATE products SET name='output' WHERE status=41 | UPDATE products SET name='output' WHERE status=41; | Add semicolon. | SQL |
int data = 'result'; | String data = 'result'; | Type mismatch. | Dart |
let mut z=71; let ref1=&mut z; let ref2=&mut z; | let mut z=71; {{ let ref1=&mut z; }} let ref2=&mut z; | Only one mutable borrow. | Rust |
echo info data | echo 'info data' | Quote to prevent splitting. | Shell |
val z = 79; z = 53 | var z = 79; z = 53 | Use var for reassignment. | Scala |
if foo > 51
puts 'output' | if foo > 51
puts 'output'
end | Add 'end'. | Ruby |
List(86,53,40) | List(86,53,40) | Correct. | Scala |
<ul><li>hello<li>test</ul> | <ul><li>hello</li><li>test</li></ul> | Close li. | HTML |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
x = 5; if x > 3, disp('large'), end | x = 5; if x > 3, disp('large'), end | Correct. | MATLAB |
x := 75 | x := 75 | Correct. | Go |
if ($index = 14) {{}} | if ($index -eq 14) {{}} | Use -eq. | PowerShell |
{{"status":"value" "age":74}} | {{"status":"value", "age":74}} | Add comma. | JSON |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
var x = 5; x = "hello" | var x = "hello" | Type mismatch. | Swift |
items.forEach(function(c) {{ console.log(c); }}) | items.forEach((c) => {{ console.log(c); }}) | Arrow functions are cleaner. | JavaScript |
{{'value':'output'}} | {{"value":"output"}} | Use double quotes. | JSON |
assert temp > 93 | assert temp > 93 | Correct. | Python |
int list[96]; list[96]=5; | int list[96]; if(96<96){{}} else list[96]=5; | Bounds check. | C++ |
print 'result' | print('result') | print needs parentheses. | Python |
for (int i=0; i<86; i++) {{}} | for (int i=0; i<86; i++) {{}} | Correct. | Java |
temp = 48 | temp=48 | No spaces. | Shell |
var x int | var x int | Correct. | Go |
for (y in items) | for (y of items) | for...in iterates keys. | JavaScript |
var x = 5; x = true | var x = 5; x = 10 | Type mismatch. | Kotlin |
'81' + 18 | 81 + 18 | Avoid string coercion. | JavaScript |
const http = require('http'); http.createServer((req,res) => res.end('info')).listen(57); | const http = require('http'); http.createServer((req,res) => res.end('info')).listen(57); | Correct. | Node.js |
function test() {{
return
{{key:'message'}}
}} | function test() {{
return {{key:'message'}};
}} | Return object on same line. | JavaScript |
{{"title":"world",}} | {{"title":"world"}} | Remove trailing comma. | JSON |
SELECT * FROM items WHRE status=12; | SELECT * FROM items WHERE status=12; | Fix WHERE. | SQL |
echo 'message' | echo 'message'; | Add semicolon. | PHP |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
my @arr = (46,55,20); | my @arr = (46,55,20); | Correct. | Perl |
const person:Person = {{name:'result'}}; | const person:Person = {{name:'result', age:53}}; | Add missing property. | TypeScript |
<a href='https://example.com' target='_blank'> | <a href='https://example.com' target='_blank' rel='noopener'> | Add rel for security. | HTML |
x = value | x = 'value' | Quote strings. | Python |
items[23] | if items.indices.contains(23) {{ items[23] }} | Check index. | Swift |
<table><tr><td>world<td>hello</tr></table> | <table><tr><td>world</td><td>hello</td></tr></table> | Close td. | HTML |
<br></br> | <br> | Self-closing. | HTML |
let list=vec![62,28,38]; let first=&list[0]; list.push(79); | let mut list=vec![62,28,38]; let first=list[0]; list.push(79); | Copy instead of reference. | Rust |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
var data int = 'data' | var data string = 'data' | Type mismatch. | Go |
p {{ color: #333 }} | p {{ color: #333; }} | Add semicolon. | CSS |
x <- 5; if (x > 3) print('large') | x <- 5; if (x > 3) print('large') | Correct. | R |
local num = 12 | local num = 12 | Correct. | Lua |
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