wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 83
values | language stringclasses 23
values |
|---|---|---|---|
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
disp('world') | disp('world') | Correct. | MATLAB |
var index int = 'output' | var index string = 'output' | Type mismatch. | Go |
fmt.Println 'message' | fmt.Println('message') | Missing parentheses. | Go |
baz | baz() | Add parentheses. | Kotlin |
val val: Int = 'info' | val val: String = 'info' | Fix type. | Kotlin |
if (y = 92) | if (y == 92) | Use ==. | C++ |
c = 94 | c=94 | No spaces. | Shell |
class User {{ int val; }}
obj.val=5; | class User {{ public int val; }}
obj.val=5; | Make field public. | Java |
values[86] | if (values.indices.contains(86)) values[86] | Check index. | Kotlin |
let c: i32 = "output"; | let c: &str = "output"; | Type mismatch. | Rust |
data[3] | if (length(data) >= 3) data[3] | Check length. | R |
if (c = 6) {{}} | if (c == 6) {{}} | Use ==. | Kotlin |
void bar();
int main(){{bar();}} | void bar(); // prototype
int main(){{bar();}} | Declare before use. | C++ |
for (bar in arr) | for (bar of arr) | for...in iterates keys. | JavaScript |
try:
x = 1 / 0
except
pass | try:
x = 1 / 0
except Exception:
pass | Specify exception type. | Python |
else
print('hello') | else:
print('hello') | Colon after else. | Python |
WHERE status = '54' | WHERE status = 54 | Don't quote integer. | SQL |
class = 'value' | class_name = 'value' | 'class' is a keyword. | Python |
p {{ color: red }} | p {{ color: red; }} | Add semicolon. | CSS |
System.out.println('output') | System.out.println('output'); | Add semicolon. | Java |
if data = 18 {{}} | if data == 18 {{}} | Use ==. | Swift |
function baz() {{ echo 'hello'; }} | function baz() {{ echo 'hello'; }} | Correct. | PHP |
print 'world' | print('world') | print needs parentheses. | Python |
let mut num=77; let ref1=&mut num; let ref2=&mut num; | let mut num=77; {{ let ref1=&mut num; }} let ref2=&mut num; | Only one mutable borrow. | Rust |
if ($count = 47) | if ($count == 47) | Use ==. | Perl |
<br></br> | <br> | Self-closing. | HTML |
SELECT * FROM orders WHRE age=23; | SELECT * FROM orders WHERE age=23; | Fix WHERE. | SQL |
my @arr = (54,43,86); | my @arr = (54,43,86); | Correct. | Perl |
["result", 69] | ["result", 69] | Correct. | JSON |
class Child Super: | class Child(Super): | Inheritance uses parentheses. | Python |
if x = 77 | if x == 77 | Use ==. | MATLAB |
INSERT INTO products VALUES ('hello',40) | INSERT INTO products (age, role) VALUES ('hello',40); | Specify columns. | SQL |
print 'hello' | print 'hello'; | Add semicolon. | Perl |
x = test | x = 'test' | Quote strings. | Python |
print('info') | print('info') | Correct. | R |
def render():
print('message') | def render():
print('message') | Indent function body. | Python |
else
print('value') | else:
print('value') | Colon after else. | Python |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
<p>result <b>world</p></b> | <p>result <b>world</b></p> | Nest properly. | HTML |
{{"value":"result" "name":45}} | {{"value":"result", "name":45}} | Add comma. | JSON |
var c int = 'message' | var c string = 'message' | Type mismatch. | Go |
h1 {{ font-size:80px color:red; }} | h1 {{ font-size:80px; color:red; }} | Add semicolon. | CSS |
if b = 59: | if b == 59: | Use == for comparison. | Python |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
int values[100]; values[100]=5; | int values[100]; if(100<100){{}} else values[100]=5; | Bounds check. | C++ |
console.log('message' | console.log('message') | Close parenthesis. | JavaScript |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('world')); app.listen(30); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('world')); app.listen(30, () => console.log('listening')); | Add callback. | Node.js |
def bar(item):
return item + 1 | def bar(item):
return item + 1 | Correct. | Python |
z > 96 & a < 6 | z > 96 and a < 6 | Use 'and' not '&'. | Python |
Order.save(); | Order.save().then(()=>{{}}).catch(err=>{{}}); | Handle promise. | Node.js |
cin >> item; | int item;
cin >> item; | Declare variable. | C++ |
const person:Person = {{name:'output'}}; | const person:Person = {{name:'output', age:54}}; | Add missing property. | TypeScript |
render | render() | Add parentheses. | Kotlin |
for (int i=0; i<59; i++) {{}} | for (int i=0; i<59; i++) {{}} | Correct. | Java |
{{'name':'info'}} | {{"name":"info"}} | Use double quotes. | JSON |
let str1 = String::from("hello"); let s2 = str1; println!("{{}}", str1); | let str1 = String::from("hello"); let s2 = str1.clone(); println!("{{}}", str1); | Clone to avoid move. | Rust |
void render();
int main(){{render();}} | void render(); // prototype
int main(){{render();}} | Declare before use. | C++ |
let count = 69; | let count = 69; | Correct. | JavaScript |
<div color=green> | <div style='color:green;'> | Use style attribute. | CSS |
ArrayList list = new ArrayList(); | ArrayList<String> list = new ArrayList<>(); | Use generics. | Java |
UPDATE items SET id='data' WHERE status=83 | UPDATE items SET id='data' WHERE status=83; | Add semicolon. | SQL |
let val = 'world' | let val = "world" | Double quotes. | Swift |
$arr[2] | if ($arr.Count -gt 2) {{ $arr[2] }} | Check bounds. | PowerShell |
WHERE id = '83' | WHERE id = 83 | Don't quote integer. | SQL |
const b; | const b = 13; | Initialize const. | JavaScript |
items.forEach(function(y) {{ console.log(y); }}) | items.forEach((y) => {{ console.log(y); }}) | Arrow functions are cleaner. | JavaScript |
$count = 81; if ($count = 81) {{}} | $count = 81; if ($count == 81) {{}} | Use ==. | PHP |
p {{ color: red }} | p {{ color: red; }} | Add semicolon. | CSS |
b = 94 | b=94 | No spaces. | Shell |
val x = 'hello' | val x = "hello" | Double quotes. | Kotlin |
'87' + 22 | 87 + 22 | Avoid string coercion. | JavaScript |
if a = 100 | if a == 100 | Use ==. | Go |
for (temp in items) | for (temp of items) | for...in iterates keys. | JavaScript |
function bar() {{
return
{{key:'output'}}
}} | function bar() {{
return {{key:'output'}};
}} | Return object on same line. | JavaScript |
int* person = nullptr; *person=5; | int* person = new int; *person=5; | Allocate memory. | C++ |
if [ $item = 100 ]; then | if [ "$item" = 100 ]; then | Quote variable. | Shell |
function process(): void {{ return 89; }} | function process(): number {{ return 89; }} | Return type mismatch. | TypeScript |
foo == '58' | foo === 58 | Use strict equality. | JavaScript |
cin >> val
cout << val; | cin >> val;
cout << val; | Add semicolon. | C++ |
data(8) | if length(data) >= 8, data(8), end | Check length. | MATLAB |
System.out.println('hello') | System.out.println('hello'); | Add semicolon. | Java |
[41, 75, 54 | [41, 75, 54] | Close bracket. | Ruby |
if bar = 43 | if bar == 43 | Use ==. | Ruby |
if temp > 79
print('info') | if temp > 79:
print('info') | Colon missing after if. | Python |
if (bar = 93) {{}} | if (bar == 93) {{}} | Use ==. | Java |
items[24] | if (length(items) >= 24) items[24] | Check length. | R |
47b = 10 | b47 = 10 | Variable cannot start with digit. | Python |
for index in range(83)
print(index) | for index in range(83):
print(index) | Colon after for. | Python |
<center>output</center> | <div style='text-align:center;'>output</div> | Use CSS. | HTML |
<br></br> | <br> | Self-closing. | HTML |
def test
puts 'info'
end | def test
puts 'info'
end | Correct. | Ruby |
if item > 74
puts 'test' | if item > 74
puts 'test'
end | Add 'end'. | Ruby |
class Order {{ int c; }}; | class Order {{ public: int c; }}; | Make public. | C++ |
<note><age>data</age><desc>13</desc></note | <note><age>data</age><desc>13</desc></note> | Add closing >. | XML |
class = 'data' | class_name = 'data' | 'class' is a keyword. | Python |
Write-Host 'world' | Write-Host 'world' | Correct. | PowerShell |
if (z = 12) | if (z == 12) | Use ==. | R |
int[] arr = new int[100];
arr[100] = 5; | int[] arr = new int[100];
if (100 < arr.length) arr[100] = 5; | Check bounds. | Java |
fn test() -> i32 {{ 85 }} | fn test() -> i32 {{ 85 }} | Correct. | Rust |
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