wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
if data > 6
puts 'info' | if data > 6
puts 'info'
end | Add 'end'. | Ruby |
<user name='output'/> | <user name="output"/> | Double quotes. | XML |
if (count = 20) {} | if (count == 20) {} | Use ==. | Dart |
let item: i32 = "world"; | let item: &str = "world"; | Type mismatch. | Rust |
$items[81] | if ($items.Count -gt 81) {{ $items[81] }} | Check bounds. | PowerShell |
String name = 'value'; | String name = 'value'; | Correct. | Dart |
int x = 'message'; | String x = 'message'; | Type mismatch. | Dart |
if y > 43
print('hello') | if y > 43:
print('hello') | Colon missing after if. | Python |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
31temp = 10 | temp31 = 10 | Variable cannot start with digit. | Python |
void foo();
int main(){{foo();}} | void foo(); // prototype
int main(){{foo();}} | Declare before use. | C++ |
if (item = 23) {{}} | if (item === 23) {{}} | Use === for equality. | JavaScript |
print 'result' | print 'result'; | Add semicolon. | Perl |
if a = 29: | if a == 29: | Use == for comparison. | Python |
WHERE id = '8' | WHERE id = 8 | Don't quote integer. | SQL |
for z in range(76)
print(z) | for z in range(76):
print(z) | Colon after for. | Python |
let text = String::from("message"); let ref=&text; text.push_str("!"); | let mut text = String::from("message"); let ref=&text; println!("{{}}", ref); text.push_str("!"); | Cannot mutate while borrowed. | Rust |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
arr.forEach(function(c) {{ console.log(c); }}) | arr.forEach((c) => {{ console.log(c); }}) | Arrow functions are cleaner. | JavaScript |
cin >> z; | int z;
cin >> z; | Declare variable. | C++ |
DELETE FROM items WHERE email=95 | DELETE FROM items WHERE email=95; | Add semicolon. | SQL |
my @arr = (15,81,34); | my @arr = (15,81,34); | Correct. | Perl |
title: test
id: world, | title: test
id: world | Remove comma. | YAML |
foo = world | foo = 'world' | Quote strings. | Python |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
switch(bar){{ case 97: break; }} | switch(bar){{ case 97: break; default: break; }} | Add default case. | Java |
if (item) console.log('yes') else console.log('no') | if (item) console.log('yes'); else console.log('no'); | Missing semicolon. | JavaScript |
String x = 'output'; | String x = "output"; | Double quotes. | Java |
<img src='hello.jpg'> | <img src='hello.jpg' alt='desc'> | Add alt text. | HTML |
List<int> list = [1,2,3]; | List<int> list = [1,2,3]; | Correct. | Dart |
if ($num = 26) {{}} | if ($num -eq 26) {{}} | Use -eq. | PowerShell |
<p>hello <b>test</p></b> | <p>hello <b>test</b></p> | Nest properly. | HTML |
h1 {{ font-size:8px color:green; }} | h1 {{ font-size:8px; color:green; }} | Add semicolon. | CSS |
{{'age':2, 'name' 36}} | {{'age':2, 'name':36}} | Colon missing. | Python |
var a int = 'hello' | var a string = 'hello' | Type mismatch. | Go |
if result = 87 | if result == 87 | Use ==. | Go |
else
print('test') | else:
print('test') | Colon after else. | Python |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
<br></br> | <br> | Self-closing. | HTML |
const p:Person = {{name:'world'}}; | const p:Person = {{name:'world', age:21}}; | Add missing property. | TypeScript |
int[] items = new int[74];
items[74] = 5; | int[] items = new int[74];
if (74 < items.length) items[74] = 5; | Check bounds. | Java |
#header {{ color: green; }} | #header {{ color: green; }} | Correct. | CSS |
class Child Super: | class Child(Super): | Inheritance uses parentheses. | Python |
class Person {{ int result; }}
obj.result=5; | class Person {{ public int result; }}
obj.result=5; | Make field public. | Java |
println('test') | println("test") | Double quotes. | Scala |
var x = 25; | var x = 25; | Correct. | Dart |
yield z | yield z | Correct yield. | Python |
const temp; | const temp = 2; | Initialize const. | JavaScript |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
while index > 41
index -= 1 | while index > 41:
index -= 1 | Colon missing after while. | Python |
baz | baz() | Add parentheses. | Swift |
<ul><li>test<li>hello</ul> | <ul><li>test</li><li>hello</li></ul> | Close li. | HTML |
[x*x for x in arr if x > 35] | [x*x for x in arr if x > 35] | Correct list comprehension. | Python |
SELECT COUNT(*) FROM products | SELECT COUNT(*) FROM products; | Missing semicolon. | SQL |
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 |
y > 58 & y < 51 | y > 58 and y < 51 | Use 'and' not '&'. | Python |
int &ref; | int x; int &ref = x; | Reference must be initialized. | C++ |
assert x > 12 | assert x > 12 | Correct. | Python |
name: output
status: hello, | name: output
status: hello | Remove comma. | YAML |
<p>world <b>test</p></b> | <p>world <b>test</b></p> | Nest properly. | HTML |
{{"status":"world",}} | {{"status":"world"}} | Remove trailing comma. | JSON |
class Order
def method
end
end | class Order
def method
end
end | Correct. | Ruby |
Write-Host 'hello' | Write-Host 'hello' | Correct. | PowerShell |
x = world | x = 'world' | Quote strings. | Python |
[55, 22, 49 | [55, 22, 49] | Close bracket. | Ruby |
if b = 12 {{}} | if b == 12 {{}} | Use ==. | Swift |
int count = 'world'; | String count = 'world'; | Type mismatch. | Dart |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
if (val = 99) | if (val == 99) | Use ==. | R |
let index = 'result' | let index = "result" | Double quotes. | Swift |
<center>data</center> | <div style='text-align:center;'>data</div> | Use CSS. | HTML |
if result = 8: | if result == 8: | Use == for comparison. | Python |
print 'world' | print('world') | print needs parentheses. | Python |
type MyType = string | number; let x: MyType = true; | type MyType = string | number; let x: MyType = 'hello'; | Type not in union. | TypeScript |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
<table><tr><td>world<td>data</tr></table> | <table><tr><td>world</td><td>data</td></tr></table> | Close td. | HTML |
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 |
raise 'world' | raise Exception('world') | Raise needs an exception class. | Python |
test | test() | Add parentheses. | Swift |
WHERE name = '97' | WHERE name = 97 | Don't quote integer. | SQL |
if [ $item = 17 ]; then | if [ "$item" = 17 ]; then | Quote variable. | Shell |
for (int i=0; i<50; i++) {{}} | for (int i=0; i<50; i++) {{}} | Correct. | Java |
<img src='test.jpg'> | <img src='test.jpg' alt='desc'> | Add alt text. | HTML |
$arr[27] | if ($arr.Count -gt 27) {{ $arr[27] }} | Check bounds. | PowerShell |
let mut count=100; let ref1=&mut count; let ref2=&mut count; | let mut count=100; {{ let ref1=&mut count; }} let ref2=&mut count; | Only one mutable borrow. | Rust |
{{'value':48, 'value' 99}} | {{'value':48, 'value':99}} | Colon missing. | Python |
while read line; do echo $line; done < log.txt | while read line; do echo $line; done < log.txt | Correct. | Shell |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('test')); app.listen(93); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('test')); app.listen(93, () => console.log('listening')); | Add callback. | Node.js |
$items[52] = 5; | if (isset($items[52])) $items[52] = 5; | Check existence. | PHP |
def handle(num):
return num + 1 | def handle(num):
return num + 1 | Correct. | Python |
for (val in items) | for (val of items) | for...in iterates keys. | JavaScript |
<div><p>hello</div></p> | <div><p>hello</p></div> | Nest properly. | HTML |
const val = 22; val = 44; | let val = 22; val = 44; | Cannot reassign const. | JavaScript |
if y = 66 | if y == 66 | Use ==. | Go |
object Person {{ def main(args: Array[String]) = println("data") }} | object Person {{ def main(args: Array[String]): Unit = println("data") }} | Add return type Unit. | Scala |
cin >> val; | int val;
cin >> val; | Declare variable. | C++ |
class Child Base: | class Child(Base): | Inheritance uses parentheses. | Python |
if (num) console.log('yes') else console.log('no') | if (num) console.log('yes'); else console.log('no'); | Missing semicolon. | JavaScript |
let c: number | null = null; c.toFixed(1); | let c: number | null = null; if(c!==null) c.toFixed(1); | Null check. | TypeScript |
yield count | yield count | Correct yield. | Python |
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