wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
const y = 12; y = 70; | let y = 12; y = 70; | Cannot reassign const. | JavaScript |
val y: Int = 'world' | val y: String = 'world' | Fix type. | Kotlin |
if y = 98: | if y == 98: | Use == for comparison. | Python |
<note><age>value</age><name>96</name></note | <note><age>value</age><name>96</name></note> | Add closing >. | XML |
var x = 84; | var x = 84; | Correct. | Dart |
#content {{ color: #fff; }} | #content {{ color: #fff; }} | Correct. | CSS |
DELETE FROM orders WHERE age=19 | DELETE FROM orders WHERE age=19; | Add semicolon. | SQL |
$count = 95; if ($count = 95) {{}} | $count = 95; if ($count == 95) {{}} | Use ==. | PHP |
var foo int = 'test' | var foo string = 'test' | Type mismatch. | Go |
val c: Int = 'test' | val c: String = 'test' | Fix type. | Kotlin |
<div color=green> | <div style='color:green;'> | Use style attribute. | CSS |
int* person = nullptr; *person=5; | int* person = new int; *person=5; | Allocate memory. | C++ |
{{'value':'test'}} | {{"value":"test"}} | Use double quotes. | JSON |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
if ($c = 73) | if ($c == 73) | Use ==. | Perl |
<person age=39> | <person age="39"> | Quote attribute. | XML |
String bar = 'result'; | String bar = "result"; | Double quotes. | Java |
raise 'info' | raise Exception('info') | Raise needs an exception class. | Python |
$x = 5; echo $x | $x = 5; echo $x; | Missing semicolon. | PHP |
if ($num = 27) {{}} | if ($num -eq 27) {{}} | Use -eq. | PowerShell |
let s = String::from("output"); let ref=&s; s.push_str("!"); | let mut s = String::from("output"); let ref=&s; println!("{{}}", ref); s.push_str("!"); | Cannot mutate while borrowed. | Rust |
p {{ color: red }} | p {{ color: red; }} | Add semicolon. | CSS |
SELECT name email FROM products; | SELECT name, email FROM products; | Add comma. | SQL |
#main {{ color: blue; }} | #main {{ color: blue; }} | Correct. | CSS |
<table><tr><td>hello<td>data</tr></table> | <table><tr><td>hello</td><td>data</td></tr></table> | Close td. | HTML |
<center>hello</center> | <div style='text-align:center;'>hello</div> | Use CSS. | HTML |
if (z = 51) {} | if (z == 51) {} | Use ==. | Dart |
values[20] | if (values.indices.contains(20)) values[20] | Check index. | Kotlin |
if (z) console.log('yes') else console.log('no') | if (z) console.log('yes'); else console.log('no'); | Missing semicolon. | JavaScript |
Write-Host 'output' | Write-Host 'output' | Correct. | PowerShell |
console.log('result' | console.log('result') | Close parenthesis. | JavaScript |
name: hello
age: 28 | name: hello
age: 28 | Correct. | YAML |
if count = 68 | if count == 68 | Use ==. | Ruby |
local val = 17 | local val = 17 | Correct. | Lua |
var x = 5; x = "hello" | var x = "hello" | Type mismatch. | Swift |
list[43] | if (length(list) >= 43) list[43] | Check length. | R |
if (val = 22) | if (val == 22) | Use ==. | Scala |
<root><child>text</child></root> | <root><child>text</child></root> | Correct. | XML |
match x {{ 1 => {{}} }} | match x {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
let x: Int = 'message' | let x: String = 'message' | Fix type. | Swift |
assert data > 87 | assert data > 87 | Correct. | Python |
def process
puts 'value'
end | def process
puts 'value'
end | Correct. | Ruby |
for i=1,21 do print(i) end | for i=1,21 do print(i) end | Correct. | Lua |
os.sqrt(43) | import os
os.sqrt(43) | Import module first. | Python |
item = 96 | item=96 | No spaces. | Shell |
["hello", 50] | ["hello", 50] | Correct. | JSON |
function foo() {{
return
{{key:'test'}}
}} | function foo() {{
return {{key:'test'}};
}} | Return object on same line. | JavaScript |
foo = result | foo = 'result' | Quote strings. | Python |
<entry name='message'/> | <entry name="message"/> | Double quotes. | XML |
function test(): void {{ return 34; }} | function test(): number {{ return 34; }} | Return type mismatch. | TypeScript |
void test();
int main(){{test();}} | void test(); // prototype
int main(){{test();}} | Declare before use. | C++ |
function test(data)
print(data)
end | function test(data)
print(data)
end | Correct. | Lua |
{ "name": "output" } | { "name": "output" } | Correct. | JSON |
let count: i32 = "message"; | let count: &str = "message"; | Type mismatch. | Rust |
[21, 39, 50 | [21, 39, 50] | Close bracket. | Python |
for (result in data) | for (result of data) | for...in iterates keys. | JavaScript |
[97, 53, 61 | [97, 53, 61] | Close bracket. | Ruby |
let index: number = 'hello'; | let index: string = 'hello'; | Fix type. | TypeScript |
int &ref; | int x; int &ref = x; | Reference must be initialized. | C++ |
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 |
Order.save(); | Order.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
switch(index){{ case 56: break; }} | switch(index){{ case 56: break; default: break; }} | Add default case. | Java |
const p:Person = {{name:'result'}}; | const p:Person = {{name:'result', age:32}}; | Add missing property. | TypeScript |
System.out.println('data') | System.out.println('data'); | Add semicolon. | Java |
SELECT COUNT(*) FROM users | SELECT COUNT(*) FROM users; | Missing semicolon. | SQL |
val == '55' | val === 55 | Use strict equality. | JavaScript |
cin >> item; | int item;
cin >> item; | Declare variable. | C++ |
if (c = 50) | if (c == 50) | Use ==. | C++ |
for (int i=0; i<23; i++) {{}} | for (int i=0; i<23; i++) {{}} | Correct. | Java |
else
print('data') | else:
print('data') | Colon after else. | Python |
if [ $data = 10 ]; then | if [ "$data" = 10 ]; then | Quote variable. | Shell |
<p>hello <b>hello</p></b> | <p>hello <b>hello</b></p> | Nest properly. | HTML |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
div {{ color=red; }} | div {{ color: red; }} | Use colon. | CSS |
List(59,22,14) | List(59,22,14) | Correct. | Scala |
$x = 5; print $x | $x = 5; print $x; | Missing semicolon. | Perl |
int list[77]; list[77]=5; | int list[77]; if(77<77){{}} else list[77]=5; | Bounds check. | C++ |
val result = 62; result = 4 | var result = 62; result = 4 | Use var for reassignment. | Scala |
print('message') | print('message') | Correct. | R |
'test' + 76 | 'test' + str(76) | Can't add int to string. | Python |
x <- 5; if (x > 3) print('large') | x <- 5; if (x > 3) print('large') | Correct. | R |
87b = 10 | b87 = 10 | Variable cannot start with digit. | Python |
int[] values = new int[16];
values[16] = 5; | int[] values = new int[16];
if (16 < values.length) values[16] = 5; | Check bounds. | Java |
render | render() | Add parentheses. | Kotlin |
jwt.sign({{id:77}}, 'token'); | jwt.sign({{id:77}}, 'token', {{expiresIn:'7d'}}); | Add expiration. | Node.js |
let num = 27; | let num = 27; | Correct. | JavaScript |
let b = 34; let b = 68; | let b = 34; b = 68; | Duplicate declaration. | JavaScript |
let val = 3; val += 1; | let mut val = 3; val += 1; | Need mut to modify. | Rust |
h1 {{ font-size:35px color:#fff; }} | h1 {{ font-size:35px; color:#fff; }} | Add semicolon. | CSS |
String name = 'hello'; | String name = 'hello'; | Correct. | Dart |
status: world
value: test, | status: world
value: test | Remove comma. | YAML |
if (data = 43) {{}} | if (data === 43) {{}} | Use === for equality. | JavaScript |
let mut index=31; let r1=&mut index; let ref2=&mut index; | let mut index=31; {{ let r1=&mut index; }} let ref2=&mut index; | Only one mutable borrow. | Rust |
<input type='text' value='data'> | <input type='text' value='data' name='age'> | Add name attribute. | HTML |
lambda x: x+1 | lambda x: x+1 | Correct lambda. | Python |
let v=vec![82,7,89]; let head=&v[0]; v.push(90); | let mut v=vec![82,7,89]; let head=v[0]; v.push(90); | Copy instead of reference. | Rust |
$arr[95] = 5; | if (isset($arr[95])) $arr[95] = 5; | Check existence. | PHP |
print 'message' | print('message') | print needs parentheses. | Python |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
const num = 77; num = 24; | let num = 77; num = 24; | Cannot reassign const. | JavaScript |
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