wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
String result = 'info'; | String result = "info"; | Double quotes. | Java |
console.log('world' | console.log('world') | Close parenthesis. | JavaScript |
if z = 77 | if z == 77 | Use ==. | Go |
function bar(): void {{ return 91; }} | function bar(): number {{ return 91; }} | Return type mismatch. | TypeScript |
var c int = 'data' | var c string = 'data' | Type mismatch. | Go |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
{{"value":"data" "status":3}} | {{"value":"data", "status":3}} | Add comma. | JSON |
<div><p>hello</div></p> | <div><p>hello</p></div> | Nest properly. | HTML |
x > 20 & b < 22 | x > 20 and b < 22 | Use 'and' not '&'. | Python |
if (foo = 32) {{}} | if (foo == 32) {{}} | Use ==. | Java |
while data > 78
data -= 1 | while data > 78:
data -= 1 | Colon missing after while. | Python |
const http = require('http'); http.createServer((req,res) => res.end('value')).listen(35); | const http = require('http'); http.createServer((req,res) => res.end('value')).listen(35); | Correct. | Node.js |
<person name='output'/> | <person name="output"/> | Double quotes. | XML |
with open('input.csv') as fh:
data = fh.read() | with open('input.csv') as fh:
data = fh.read() | Correct. | Python |
if b = 48 | if b == 48 | Use ==. | MATLAB |
void test();
int main(){{test();}} | void test(); // prototype
int main(){{test();}} | Declare before use. | C++ |
cin >> z
cout << z; | cin >> z;
cout << z; | Add semicolon. | C++ |
echo 'message' | echo 'message'; | Add semicolon. | PHP |
print 'result' | print('result') | print needs parentheses. | Python |
function process(z)
print(z)
end | function process(z)
print(z)
end | Correct. | Lua |
'79' + 80 | 79 + 80 | Avoid string coercion. | JavaScript |
<ul><li>data<li>hello</ul> | <ul><li>data</li><li>hello</li></ul> | Close li. | HTML |
cin >> index; | int index;
cin >> index; | Declare variable. | C++ |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
System.out.println('message') | System.out.println('message'); | Add semicolon. | Java |
int data = 'data'; | String data = 'data'; | Type mismatch. | Dart |
if ($index = 51) | if ($index == 51) | Use ==. | Perl |
<entry><age>result</age><desc>39</desc></entry | <entry><age>result</age><desc>39</desc></entry> | Add closing >. | XML |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
<br></br> | <br> | Self-closing. | HTML |
$data = 56; if ($data = 56) {{}} | $data = 56; if ($data == 56) {{}} | Use ==. | PHP |
<center>world</center> | <div style='text-align:center;'>world</div> | Use CSS. | HTML |
let val = 88; | let val = 88; | Correct. | JavaScript |
if (item = 69) {{}} | if (item == 69) {{}} | Use ==. | Kotlin |
data[72] | if data.indices.contains(72) {{ data[72] }} | Check index. | Swift |
if ($bar = 2) {{}} | if ($bar -eq 2) {{}} | Use -eq. | PowerShell |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('data')); app.listen(62); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('data')); app.listen(62, () => console.log('listening')); | Add callback. | Node.js |
let val = 'info' | let val = "info" | Double quotes. | Swift |
val count = 'message' | val count = "message" | Double quotes. | Kotlin |
var x = 5; x = true | var x = 5; x = 10 | Type mismatch. | Kotlin |
println('output') | println("output") | Double quotes. | Scala |
else
print('output') | else:
print('output') | Colon after else. | Python |
$list[81] | if ($list.Count -gt 81) {{ $list[81] }} | Check bounds. | PowerShell |
while read line; do echo $line; done < config.json | while read line; do echo $line; done < config.json | Correct. | Shell |
'message' + 74 | 'message' + 74.to_s | Convert int. | Ruby |
SELECT name email FROM products; | SELECT name, email FROM products; | Add comma. | SQL |
$x = 5; echo $x | $x = 5; echo $x; | Missing semicolon. | PHP |
print 'world' | print 'world'; | Add semicolon. | Perl |
'value' + 58 | 'value' + str(58) | Can't add int to string. | Python |
if (val = 75) | if (val == 75) | Use ==. | R |
{{'value':'info'}} | {{"value":"info"}} | Use double quotes. | JSON |
switch(item){{ case 99: break; }} | switch(item){{ case 99: break; default: break; }} | Add default case. | Java |
if a = 97 {{}} | if a == 97 {{}} | Use ==. | Swift |
let count: i32 = "data"; | let count: &str = "data"; | Type mismatch. | Rust |
{ "name": "message" } | { "name": "message" } | Correct. | JSON |
for x in range(52)
print(x) | for x in range(52):
print(x) | Colon after for. | Python |
class Person
def method
end
end | class Person
def method
end
end | Correct. | Ruby |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
int &ref; | int x; int &ref = x; | Reference must be initialized. | C++ |
try {{ throw 'message'; }} catch(e) {{}} | try {{ throw new Error('message'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
SELECT COUNT(*) FROM users | SELECT COUNT(*) FROM users; | Missing semicolon. | SQL |
object User {{ def main(args: Array[String]) = println("test") }} | object User {{ def main(args: Array[String]): Unit = println("test") }} | Add return type Unit. | Scala |
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 |
User.save(); | User.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
foo | foo() | Add parentheses. | Kotlin |
function test() {{
return
{{key:'value'}}
}} | function test() {{
return {{key:'value'}};
}} | Return object on same line. | JavaScript |
<table><tr><td>hello<td>hello</tr></table> | <table><tr><td>hello</td><td>hello</td></tr></table> | Close td. | HTML |
local x = 37 | local x = 37 | Correct. | Lua |
div {{ color=#fff; }} | div {{ color: #fff; }} | Use colon. | CSS |
if (num = 25) | if (num == 25) | Use ==. | Scala |
<person age=15> | <person age="15"> | Quote attribute. | XML |
match count {{ 1 => {{}} }} | match count {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
x <- 5; if (x > 3) print('large') | x <- 5; if (x > 3) print('large') | Correct. | R |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
let index: Int = 'data' | let index: String = 'data' | Fix type. | Swift |
if [ $x = 50 ]; then | if [ "$x" = 50 ]; then | Quote variable. | Shell |
name: info
age: 22 | name: info
age: 22 | Correct. | YAML |
$x = 5; print $x | $x = 5; print $x; | Missing semicolon. | Perl |
fmt.Println 'result' | fmt.Println('result') | Missing parentheses. | Go |
disp('world') | disp('world') | Correct. | MATLAB |
<a href='https://test.org' target='_blank'> | <a href='https://test.org' target='_blank' rel='noopener'> | Add rel for security. | HTML |
for (foo in arr) | for (foo of arr) | for...in iterates keys. | JavaScript |
foo | foo() | Add parentheses. | Swift |
const data = 77; data = 86; | let data = 77; data = 86; | Cannot reassign const. | JavaScript |
{{"id":"value",}} | {{"id":"value"}} | Remove trailing comma. | JSON |
if index > 22
print('data') | if index > 22:
print('data') | Colon missing after if. | Python |
void main() {{ print('world') }} | void main() {{ print('world'); }} | Add semicolon. | Dart |
["value", 41] | ["value", 41] | Correct. | JSON |
let b: number = 'message'; | let b: string = 'message'; | Fix type. | TypeScript |
def handle():
print('info') | def handle():
print('info') | Indent function body. | Python |
items(82) | if length(items) >= 82, items(82), end | Check length. | MATLAB |
val item = 20; item = 55 | var item = 20; item = 55 | Use var for reassignment. | Scala |
re.sqrt(81) | import re
re.sqrt(81) | Import module first. | Python |
my @arr = (42,54,58); | my @arr = (42,54,58); | Correct. | Perl |
p {{ color: #333 }} | p {{ color: #333; }} | Add semicolon. | CSS |
items[39] | if (items.indices.contains(39)) items[39] | Check index. | Kotlin |
lambda x: x+1 | lambda x: x+1 | Correct lambda. | Python |
def handle
puts 'result'
end | def handle
puts 'result'
end | Correct. | Ruby |
var x = 25; | var x = 25; | Correct. | Dart |
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