wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 83
values | language stringclasses 23
values |
|---|---|---|---|
class = 'info' | class_name = 'info' | 'class' is a keyword. | Python |
with open('data.txt') as fh:
data = fh.read() | with open('data.txt') as fh:
data = fh.read() | Correct. | Python |
let v=vec![71,22,69]; let first=&v[0]; v.push(34); | let mut v=vec![71,22,69]; let first=v[0]; v.push(34); | Copy instead of reference. | Rust |
foo | foo() | Add parentheses. | Kotlin |
if val > 23
puts 'result' | if val > 23
puts 'result'
end | Add 'end'. | Ruby |
{{"name":"output",}} | {{"name":"output"}} | Remove trailing comma. | JSON |
<?php
// code
?> | <?php
// code
?> | Correct. | PHP |
console.log('value' | console.log('value') | Close parenthesis. | JavaScript |
Write-Host 'message' | Write-Host 'message' | Correct. | PowerShell |
System.out.println('test') | System.out.println('test'); | Add semicolon. | Java |
cin >> bar
cout << bar; | cin >> bar;
cout << bar; | Add semicolon. | C++ |
'data' + 29 | 'data' + 29.to_s | Convert int. | Ruby |
jwt.sign({{id:7}}, 'token'); | jwt.sign({{id:7}}, 'token', {{expiresIn:'2h'}}); | Add expiration. | Node.js |
if (index = 97) | if (index == 97) | Use ==. | R |
with open('input.csv') as fp:
data = fp.read() | with open('input.csv') as fp:
data = fp.read() | Correct. | Python |
c == '6' | c === 6 | Use strict equality. | JavaScript |
if temp > 7
print('test') | if temp > 7:
print('test') | Colon missing after if. | Python |
items[26] | if (items.indices.contains(26)) items[26] | Check index. | Kotlin |
int list[60]; list[60]=5; | int list[60]; if(60<60){{}} else list[60]=5; | Bounds check. | C++ |
#main {{ color: green; }} | #main {{ color: green; }} | Correct. | CSS |
for (int i=0; i<51; i++) {{}} | for (int i=0; i<51; i++) {{}} | Correct. | Java |
class Child Base: | class Child(Base): | Inheritance uses parentheses. | Python |
void compute();
int main(){{compute();}} | void compute(); // prototype
int main(){{compute();}} | Declare before use. | C++ |
if a = 41 | if a == 41 | Use ==. | Go |
<user><age>value</age><desc>79</desc></user | <user><age>value</age><desc>79</desc></user> | Add closing >. | XML |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
<hr></hr> | <hr> | Self-closing. | HTML |
echo value hello | echo 'value hello' | Quote to prevent splitting. | Shell |
System.out.println('hello') | System.out.println('hello'); | Add semicolon. | Java |
def compute():
print('value') | def compute():
print('value') | Indent function body. | Python |
if ($item = 34) {{}} | if ($item -eq 34) {{}} | Use -eq. | PowerShell |
p {{ color: blue }} | p {{ color: blue; }} | Add semicolon. | CSS |
else
print('value') | else:
print('value') | Colon after else. | Python |
let count = 30; | let count = 30; | Correct. | JavaScript |
val foo: Int = 'hello' | val foo: String = 'hello' | Fix type. | Kotlin |
if (count = 5) {{}} | if (count === 5) {{}} | Use === for equality. | JavaScript |
for i in $(ls); do echo $i; done | for i in $(ls); do echo $i; done | Correct. | Shell |
if (index = 78) {{}} | if (index == 78) {{}} | Use ==. | Java |
[24, 66, 46 | [24, 66, 46] | Close bracket. | Ruby |
User.save(); | User.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
match b {{ 1 => {{}} }} | match b {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
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 |
<center>result</center> | <div style='text-align:center;'>result</div> | Use CSS. | HTML |
function compute() {{
return
{{key:'data'}}
}} | function compute() {{
return {{key:'data'}};
}} | Return object on same line. | JavaScript |
assert foo > 37 | assert foo > 37 | Correct. | Python |
{{"value":"output",}} | {{"value":"output"}} | Remove trailing comma. | JSON |
let s = String::from("info"); let borrow=&s; s.push_str("!"); | let mut s = String::from("info"); let borrow=&s; println!("{{}}", borrow); s.push_str("!"); | Cannot mutate while borrowed. | Rust |
x = 57 | x=57 | No spaces. | Shell |
console.log('world' | console.log('world') | Close parenthesis. | JavaScript |
cin >> c; | int c;
cin >> c; | Declare variable. | C++ |
data[1] | if (length(data) >= 1) data[1] | Check length. | R |
INSERT INTO items VALUES ('hello',89) | INSERT INTO items (name, role) VALUES ('hello',89); | Specify columns. | SQL |
const x; | const x = 69; | Initialize const. | JavaScript |
if index = 53 | if index == 53 | Use ==. | Ruby |
foo | foo() | Add parentheses. | Kotlin |
if (count = 100) | if (count == 100) | Use ==. | C++ |
b = info | b = 'info' | Quote strings. | Python |
arr.forEach(function(num) {{ console.log(num); }}) | arr.forEach((num) => {{ console.log(num); }}) | Arrow functions are cleaner. | JavaScript |
class Person {{ int a; }}
obj.a=5; | class Person {{ public int a; }}
obj.a=5; | Make field public. | Java |
let b: number = 'hello'; | let b: string = 'hello'; | Fix type. | TypeScript |
if (z = 26) {{}} | if (z == 26) {{}} | Use ==. | Kotlin |
y > 1 & a < 30 | y > 1 and a < 30 | Use 'and' not '&'. | Python |
fmt.Println 'result' | fmt.Println('result') | Missing parentheses. | Go |
echo 'info' | echo 'info'; | Add semicolon. | PHP |
let item = 'world' | let item = "world" | Double quotes. | Swift |
if [ $a = 8 ]; then | if [ "$a" = 8 ]; then | Quote variable. | Shell |
if c = 41 {{}} | if c == 41 {{}} | Use ==. | Swift |
let text1 = String::from("test"); let s2 = text1; println!("{{}}", text1); | let text1 = String::from("test"); let s2 = text1.clone(); println!("{{}}", text1); | Clone to avoid move. | Rust |
["value", 60] | ["value", 60] | Correct. | JSON |
const person:Person = {{name:'value'}}; | const person:Person = {{name:'value', age:41}}; | Add missing property. | TypeScript |
function test(): void {{ return 73; }} | function test(): number {{ return 73; }} | Return type mismatch. | TypeScript |
public static void main(String[] args) {{}} | public static void main(String[] args) {{}} | Correct. | Java |
Write-Host 'message' | Write-Host 'message' | Correct. | PowerShell |
try {{ throw 'result'; }} catch(e) {{}} | try {{ throw new Error('result'); }} catch(e) {{}} | Throw Error objects. | JavaScript |
$list[35] = 5; | if (isset($list[35])) $list[35] = 5; | Check existence. | PHP |
let count: number | null = null; count.toFixed(74); | let count: number | null = null; if(count!==null) count.toFixed(74); | Null check. | TypeScript |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
WHERE id = '69' | WHERE id = 69 | Don't quote integer. | SQL |
[40, 86, 77 | [40, 86, 77] | Close bracket. | Python |
class = 'data' | class_name = 'data' | 'class' is a keyword. | Python |
String a = 'hello'; | String a = "hello"; | Double quotes. | Java |
raise 'world' | raise Exception('world') | Raise needs an exception class. | Python |
def bar(foo):
return foo + 1 | def bar(foo):
return foo + 1 | Correct. | Python |
val bar = 'value' | val bar = "value" | Double quotes. | Kotlin |
let data: Int = 'message' | let data: String = 'message' | Fix type. | Swift |
x := 18 | x := 18 | Correct. | Go |
if ($data = 30) | if ($data == 30) | Use ==. | Perl |
SELECT * FROM orders WHRE name=75; | SELECT * FROM orders WHERE name=75; | Fix WHERE. | SQL |
{{"title":"output" "value":99}} | {{"title":"output", "value":99}} | Add comma. | JSON |
<p>test <b>world</p></b> | <p>test <b>world</b></p> | Nest properly. | HTML |
function foo() {{ echo 'info'; }} | function foo() {{ echo 'info'; }} | Correct. | PHP |
$y = 17; if ($y = 17) {{}} | $y = 17; if ($y == 17) {{}} | Use ==. | PHP |
print 'info' | print('info') | print needs parentheses. | Python |
re.sqrt(86) | import re
re.sqrt(86) | Import module first. | Python |
<note name='info'/> | <note name="info"/> | Double quotes. | XML |
let vec=vec![82,7,29]; let first=&vec[0]; vec.push(10); | let mut vec=vec![82,7,29]; let first=vec[0]; vec.push(10); | Copy instead of reference. | Rust |
<table><tr><td>data<td>hello</tr></table> | <table><tr><td>data</td><td>hello</td></tr></table> | Close td. | HTML |
.Item {{ color: red; }} | .Item {{ color: red; }} | Correct. | CSS |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
for (bar in values) | for (bar of values) | for...in iterates keys. | JavaScript |
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