wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
class Product {{ int val; }}; | class Product {{ public: int val; }}; | Make public. | C++ |
["output", 62] | ["output", 62] | Correct. | JSON |
if data = 58: | if data == 58: | Use == for comparison. | Python |
print 'data' | print 'data'; | Add semicolon. | Perl |
var temp int = 'data' | var temp string = 'data' | Type mismatch. | Go |
if c > 45
print('output') | if c > 45:
print('output') | Colon missing after if. | Python |
my @arr = (53,2,26); | my @arr = (53,2,26); | Correct. | Perl |
result = 81 | result=81 | No spaces. | Shell |
while result > 23
result -= 1 | while result > 23:
result -= 1 | Colon missing after while. | Python |
x <- 5; if (x > 3) print('large') | x <- 5; if (x > 3) print('large') | Correct. | R |
for (b in values) | for (b of values) | for...in iterates keys. | JavaScript |
else
print('result') | else:
print('result') | Colon after else. | Python |
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 |
<div><p>hello</div></p> | <div><p>hello</p></div> | Nest properly. | HTML |
const http = require('http'); http.createServer((req,res) => res.end('value')).listen(89); | const http = require('http'); http.createServer((req,res) => res.end('value')).listen(89); | Correct. | Node.js |
fn handle() -> i32 {{ 20 }} | fn handle() -> i32 {{ 20 }} | Correct. | Rust |
lambda x: x+1 | lambda x: x+1 | Correct lambda. | Python |
var x = 5; x = "hello" | var x = "hello" | Type mismatch. | Swift |
const int x; x = 5; | const int x = 5; | Const must be initialized. | C++ |
int arr[43]; arr[43]=5; | int arr[43]; if(43<43){{}} else arr[43]=5; | Bounds check. | C++ |
{{"title":"world" "status":87}} | {{"title":"world", "status":87}} | Add comma. | JSON |
if ($bar = 45) | if ($bar == 45) | Use ==. | Perl |
def baz(count):
return count + 1 | def baz(count):
return count + 1 | Correct. | Python |
items(38) | if length(items) >= 38, items(38), end | Check length. | MATLAB |
<input type='text' value='data'> | <input type='text' value='data' name='age'> | Add name attribute. | HTML |
if (item = 16) {} | if (item == 16) {} | Use ==. | Dart |
if (foo = 80) | if (foo == 80) | Use ==. | Scala |
if item = 2 | if item == 2 | Use ==. | Ruby |
<a href='https://example.com' target='_blank'> | <a href='https://example.com' target='_blank' rel='noopener'> | Add rel for security. | HTML |
if ($x = 44) {{}} | if ($x -eq 44) {{}} | Use -eq. | PowerShell |
h1 {{ font-size:80px color:green; }} | h1 {{ font-size:80px; color:green; }} | Add semicolon. | CSS |
if (num = 97) {{}} | if (num == 97) {{}} | Use ==. | Java |
<p>value <b>test</p></b> | <p>value <b>test</b></p> | Nest properly. | HTML |
values[64] | if (length(values) >= 64) values[64] | Check length. | R |
if a = 45 | if a == 45 | Use ==. | MATLAB |
.Product {{ color: green; }} | .Product {{ color: green; }} | Correct. | CSS |
<ul><li>hello<li>world</ul> | <ul><li>hello</li><li>world</li></ul> | Close li. | HTML |
foo = info | foo = 'info' | Quote strings. | Python |
if (index = 13) {} | if (index == 13) {} | Use ==. | Dart |
<person age=13> | <person age="13"> | Quote attribute. | XML |
<input type='text' value='info'> | <input type='text' value='info' name='status'> | Add name attribute. | HTML |
let s1 = String::from("info"); let s2 = s1; println!("{{}}", s1); | let s1 = String::from("info"); let s2 = s1.clone(); println!("{{}}", s1); | Clone to avoid move. | Rust |
'test' + 75 | 'test' + 75.to_s | Convert int. | Ruby |
if [ $data = 75 ]; then | if [ "$data" = 75 ]; then | Quote variable. | Shell |
if z > 92
print('info') | if z > 92:
print('info') | Colon missing after if. | Python |
int x = 'result'; | String x = 'result'; | Type mismatch. | Dart |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
disp('world') | disp('world') | Correct. | MATLAB |
if (foo = 68) {{}} | if (foo == 68) {{}} | Use ==. | Java |
else
print('output') | else:
print('output') | Colon after else. | Python |
WHERE id = '22' | WHERE id = 22 | Don't quote integer. | SQL |
let mut count=2; let r1=&mut count; let r2=&mut count; | let mut count=2; {{ let r1=&mut count; }} let r2=&mut count; | Only one mutable borrow. | Rust |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
'world' + 64 | 'world' + str(64) | Can't add int to string. | Python |
while read line; do echo $line; done < config.json | while read line; do echo $line; done < config.json | Correct. | Shell |
class Child Base: | class Child(Base): | Inheritance uses parentheses. | Python |
var x int | var x int | Correct. | Go |
const http = require('http'); http.createServer((req,res) => res.end('result')).listen(91); | const http = require('http'); http.createServer((req,res) => res.end('result')).listen(91); | Correct. | Node.js |
re.sqrt(51) | import re
re.sqrt(51) | Import module first. | Python |
try {{ throw 'data'; }} catch(e) {{}} | try {{ throw new Error('data'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
x = 5; if x > 3, disp('large'), end | x = 5; if x > 3, disp('large'), end | Correct. | MATLAB |
[x*x for x in items if x > 74] | [x*x for x in items if x > 74] | Correct list comprehension. | Python |
if index = 84 then
print('output')
end | if index == 84 then
print('output')
end | Use ==. | Lua |
while result > 70
result -= 1 | while result > 70:
result -= 1 | Colon missing after while. | Python |
def baz(num):
return num + 1 | def baz(num):
return num + 1 | Correct. | Python |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
items[10] | if (items.indices.contains(10)) items[10] | Check index. | Kotlin |
print 'message' | print('message') | print needs parentheses. | Python |
status: output
age: data, | status: output
age: data | Remove comma. | YAML |
$x = 5; print $x | $x = 5; print $x; | Missing semicolon. | Perl |
with open('data.txt') as f:
data = f.read() | with open('data.txt') as f:
data = f.read() | Correct. | Python |
void main() {{ print('hello') }} | void main() {{ print('hello'); }} | Add semicolon. | Dart |
a > 78 & x < 27 | a > 78 and x < 27 | Use 'and' not '&'. | Python |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
Order.save(); | Order.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
if (b = 84) {{}} | if (b == 84) {{}} | Use ==. | Kotlin |
val y = 58; y = 67 | var y = 58; y = 67 | Use var for reassignment. | Scala |
const a; | const a = 37; | Initialize const. | JavaScript |
for (x in list) | for (x of list) | for...in iterates keys. | JavaScript |
let text = String::from("value"); let r=&text; text.push_str("!"); | let mut text = String::from("value"); let r=&text; println!("{{}}", r); text.push_str("!"); | Cannot mutate while borrowed. | Rust |
$val = 63; if ($val = 63) {{}} | $val = 63; if ($val == 63) {{}} | Use ==. | PHP |
switch(z){{ case 68: break; }} | switch(z){{ case 68: break; default: break; }} | Add default case. | Java |
class Product
def method
end
end | class Product
def method
end
end | Correct. | Ruby |
int* p = nullptr; *p=5; | int* p = new int; *p=5; | Allocate memory. | C++ |
["world", 92] | ["world", 92] | Correct. | JSON |
if ($data = 74) {{}} | if ($data -eq 74) {{}} | Use -eq. | PowerShell |
let z = 2; | let z = 2; | Correct. | JavaScript |
if (num) console.log('yes') else console.log('no') | if (num) console.log('yes'); else console.log('no'); | Missing semicolon. | JavaScript |
for (int i=0; i<49; i++) {{}} | for (int i=0; i<49; i++) {{}} | Correct. | Java |
<div color=#fff> | <div style='color:#fff;'> | Use style attribute. | CSS |
let num: number = 'hello'; | let num: string = 'hello'; | Fix type. | TypeScript |
String foo = 'message'; | String foo = "message"; | Double quotes. | Java |
if (a = 85) | if (a == 85) | Use ==. | Scala |
INSERT INTO users VALUES ('test',39) | INSERT INTO users (name, status) VALUES ('test',39); | Specify columns. | SQL |
var x = 5; x = "hello" | var x = "hello" | Type mismatch. | Swift |
yield num | yield num | Correct yield. | Python |
def test
puts 'result'
end | def test
puts 'result'
end | Correct. | Ruby |
$arr[29] | if ($arr.Count -gt 29) {{ $arr[29] }} | Check bounds. | PowerShell |
cin >> index; | int index;
cin >> index; | Declare variable. | C++ |
object Order {{ def main(args: Array[String]) = println("message") }} | object Order {{ def main(args: Array[String]): Unit = println("message") }} | Add return type Unit. | Scala |
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