Write a function that checks whether a number is a valid US phone number or not. We will call a phone number valid if it has the following format (DDD) DDD-DDDD, where D is any digit from 0-9.

Note: Assume that the space, parentheses and hyphen must be in the correct places for it to be called a valid phone number.

What is the output of the following code?

bool is_valid_phone(string s) {
    # Write your code here
}

What does the following code output?

type=codeblock|id=cpp_phone_format_exercise|autocreate=cpp
string arr[] = {
  "(386) 531-7373", "(929) 5h7-9593", "(512) 225-2430", "(967) 879-4329", "(996) 367-4342", 
  "(968) 231-7724", ")485) 371-9565", "(991( 229-7475", "(540) 854-9332", "(419) 78l-9501", 
  "(644)-777 0654", "(283) 315-3253", "(802) 989 6657", ")269) 4.9-1568", "(221) 598-6816", 
  "(739) 5.3-4035", "(612) 894-3527", "(294) 828-2107", "(596) 407-1286", ")476( 465-0360", 
  "(444) 463-8623", "(294) 298-6535", "(327) 494-6850", "(981) 407-4008", "(487) 445-6039", 
  "(414) 974-6492", "(585) 944-5746", "(229) 2.7-6823", "(913) 235-9351", "(342)-827-2002", 
  "(611) 525-5476", "(490( 790-4362", "(538) 588-8926", "(584) 457-6424", "(413) 960-8316", 
  "(537) 890-5846", "(383) 673-8735", "(611) 767-6100", "(442(-637-4470", "(555) 282-2178", 
  ")711) 879-8914", "(936) 899-2363", "(490)-920-8058", ")559)-636 1936", "(668) 87h-7616", 
  "(966) 5h9-9321", "(655) 516 1419", "(698) 53l-6766", "(413) 813-6578", "(844) 839-8190", 
};
 
int count = 0; 
for (int i = 0; i < 50; i++)
    if (is_valid_phone(arr[i])) 
        count++; 
cout << count << endl;