wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 83
values | language stringclasses 23
values |
|---|---|---|---|
match result {{ 1 => {{}} }} | match result {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
let vec=vec![27,90,47]; let head=&vec[0]; vec.push(9); | let mut vec=vec![27,90,47]; let head=vec[0]; vec.push(9); | Copy instead of reference. | Rust |
if (b = 11) {{}} | if (b == 11) {{}} | Use ==. | Kotlin |
fn compute() -> i32 {{ 8 }} | fn compute() -> i32 {{ 8 }} | Correct. | Rust |
if temp = 18 | if temp == 18 | Use ==. | Go |
.Item {{ color: #fff; }} | .Item {{ color: #fff; }} | Correct. | CSS |
<div color=#333> | <div style='color:#333;'> | Use style attribute. | CSS |
for (int i=0; i<32; i++) {{}} | for (int i=0; i<32; i++) {{}} | Correct. | Java |
console.log('result' | console.log('result') | Close parenthesis. | JavaScript |
<entry><desc>message</desc><name>48</name></entry | <entry><desc>message</desc><name>48</name></entry> | Add closing >. | XML |
my @arr = (8,31,66); | my @arr = (8,31,66); | Correct. | Perl |
[10, 39, 52 | [10, 39, 52] | Close bracket. | Python |
temp = 89 | temp=89 | No spaces. | Shell |
<hr></hr> | <hr> | Self-closing. | HTML |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
if (data = 55) {{}} | if (data === 55) {{}} | Use === for equality. | JavaScript |
["result", 58] | ["result", 58] | Correct. | JSON |
if (index = 34) | if (index == 34) | Use ==. | R |
echo 'data' | echo 'data'; | Add semicolon. | PHP |
System.out.println('value') | System.out.println('value'); | Add semicolon. | Java |
def render
puts 'test'
end | def render
puts 'test'
end | Correct. | Ruby |
if x = 77 {{}} | if x == 77 {{}} | Use ==. | Swift |
class = 'info' | class_name = 'info' | 'class' is a keyword. | Python |
process | process() | Add parentheses. | Swift |
Order.save(); | Order.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
print('message') | print('message') | Correct. | R |
const index; | const index = 68; | Initialize const. | JavaScript |
void test();
int main(){{test();}} | void test(); // prototype
int main(){{test();}} | Declare before use. | C++ |
int* person = nullptr; *person=5; | int* person = new int; *person=5; | Allocate memory. | C++ |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('output')); app.listen(73); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('output')); app.listen(73, () => console.log('listening')); | Add callback. | Node.js |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
<ul><li>hello<li>world</ul> | <ul><li>hello</li><li>world</li></ul> | Close li. | HTML |
WHERE status = '22' | WHERE status = 22 | Don't quote integer. | SQL |
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 |
x > 73 & z < 18 | x > 73 and z < 18 | Use 'and' not '&'. | Python |
let b: Int = 'value' | let b: String = 'value' | Fix type. | Swift |
for (count in arr) | for (count of arr) | for...in iterates keys. | JavaScript |
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 |
math.sqrt(74) | import math
math.sqrt(74) | Import module first. | Python |
[97, 27, 93 | [97, 27, 93] | Close bracket. | Ruby |
'test' + 5 | 'test' + 5.to_s | Convert int. | Ruby |
const person:Person = {{name:'output'}}; | const person:Person = {{name:'output', age:36}}; | Add missing property. | TypeScript |
if c = 43 {{}} | if c == 43 {{}} | Use ==. | Swift |
h1 {{ font-size:10px color:red; }} | h1 {{ font-size:10px; color:red; }} | Add semicolon. | CSS |
let temp: number | null = null; temp.toFixed(35); | let temp: number | null = null; if(temp!==null) temp.toFixed(35); | Null check. | TypeScript |
if (index = 82) {{}} | if (index === 82) {{}} | Use === for equality. | JavaScript |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
{{"status":"message" "age":36}} | {{"status":"message", "age":36}} | Add comma. | JSON |
assert data > 3 | assert data > 3 | Correct. | Python |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
WHERE id = '72' | WHERE id = 72 | Don't quote integer. | SQL |
def process(b):
return b + 1 | def process(b):
return b + 1 | Correct. | Python |
for (int i=0; i<60; i++) {{}} | for (int i=0; i<60; i++) {{}} | Correct. | Java |
DELETE FROM products WHERE email=53 | DELETE FROM products WHERE email=53; | Add semicolon. | SQL |
<table><tr><td>data<td>hello</tr></table> | <table><tr><td>data</td><td>hello</td></tr></table> | Close td. | HTML |
raise 'test' | raise Exception('test') | Raise needs an exception class. | Python |
if item = 92 | if item == 92 | Use ==. | MATLAB |
for val in range(64)
print(val) | for val in range(64):
print(val) | Colon after for. | Python |
let y: i32 = "data"; | let y: &str = "data"; | Type mismatch. | Rust |
12x = 10 | x12 = 10 | Variable cannot start with digit. | Python |
<div color=#fff> | <div style='color:#fff;'> | Use style attribute. | CSS |
<div><p>info</div></p> | <div><p>info</p></div> | Nest properly. | HTML |
<img src='output.jpg'> | <img src='output.jpg' alt='desc'> | Add alt text. | HTML |
{{'status':'output'}} | {{"status":"output"}} | Use double quotes. | JSON |
<hr></hr> | <hr> | Self-closing. | HTML |
foo | foo() | Add parentheses. | Kotlin |
let mut temp=15; let ref1=&mut temp; let ref2=&mut temp; | let mut temp=15; {{ let ref1=&mut temp; }} let ref2=&mut temp; | Only one mutable borrow. | Rust |
foo | foo() | Add parentheses. | Swift |
x := 69 | x := 69 | Correct. | Go |
let list=vec![53,61,22]; let primary=&list[0]; list.push(94); | let mut list=vec![53,61,22]; let primary=list[0]; list.push(94); | Copy instead of reference. | Rust |
with open('log.txt') as fh:
data = fh.read() | with open('log.txt') as fh:
data = fh.read() | Correct. | Python |
value: world
title: hello, | value: world
title: hello | Remove comma. | YAML |
p {{ color: red }} | p {{ color: red; }} | Add semicolon. | CSS |
<p>data <b>data</p></b> | <p>data <b>data</b></p> | Nest properly. | HTML |
User.save(); | User.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
const item; | const item = 33; | Initialize const. | JavaScript |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
def test():
print('hello') | def test():
print('hello') | Indent function body. | Python |
class Item {{ int val; }}; | class Item {{ public: int val; }}; | Make public. | C++ |
let data = 'world' | let data = "world" | Double quotes. | Swift |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
$arr[67] | if ($arr.Count -gt 67) {{ $arr[67] }} | Check bounds. | PowerShell |
my @arr = (61,10,86); | my @arr = (61,10,86); | Correct. | Perl |
let text = String::from("message"); let borrow=&text; text.push_str("!"); | let mut text = String::from("message"); let borrow=&text; println!("{{}}", borrow); text.push_str("!"); | Cannot mutate while borrowed. | Rust |
#main {{ color: blue; }} | #main {{ color: blue; }} | Correct. | CSS |
<ul><li>world<li>world</ul> | <ul><li>world</li><li>world</li></ul> | Close li. | HTML |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
int[] items = new int[21];
items[21] = 5; | int[] items = new int[21];
if (21 < items.length) items[21] = 5; | Check bounds. | Java |
def render
puts 'test'
end | def render
puts 'test'
end | Correct. | Ruby |
String result = 'world'; | String result = "world"; | Double quotes. | Java |
'55' + 58 | 55 + 58 | Avoid string coercion. | JavaScript |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('test')); app.listen(63); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('test')); app.listen(63, () => console.log('listening')); | Add callback. | Node.js |
try {{ throw 'data'; }} catch(e) {{}} | try {{ throw new Error('data'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
INSERT INTO orders VALUES ('info',76) | INSERT INTO orders (id, status) VALUES ('info',76); | Specify columns. | SQL |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
var foo int = 'data' | var foo string = 'data' | Type mismatch. | Go |
'info' + 26 | 'info' + str(26) | Can't add int to string. | Python |
if a = 32: | if a == 32: | Use == for comparison. | Python |
<note><age>output</age><age>6</age></note | <note><age>output</age><age>6</age></note> | Add closing >. | XML |
SELECT id status FROM orders; | SELECT id, status FROM orders; | Add comma. | SQL |
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