How do I get my program to count the number of special characters using a while loop?

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C++

The program needs to be able to print the number of lowercase letters, uppercase letters, numbers, and special characters that a string with no spaces that the user enters has. i have everything except how to do the special characters. any suggestions?

#include <iostream>
#include <string> 
using namespace std ;


int main()
{
    char str[100]  ;     // character string max is 100 characters
    int i ;
    int upperCase ;
    int num ;
    int lowerCase ;
    int spec ;
    
    cout << "Please enter a continuous string of characters with no spaces" << endl ;
    cout << "(example: ASO@23iow$)" << endl << endl ;   //shows an example and then adds a blank line
    cout << "Enter your string: " ;
    cin >> str ;
    cout << endl ;
    
    
    i = 0 ;
    
    while(str[i] != 0)
    {
        if ((str[i] >= 'a') && (str[i] <= 'z'))   // "i" represents each idividual character that the computer is checking
            lowerCase++ ;                        // if "i" is within a-z the computer adds 1 to variable "lowerCase"
        if ((str[i] >= '0') && (str[i] <= '9'))
            num++ ;
        if ((str[i] >= 'A') && (str[i] <= 'Z'))
            upperCase++ ;
            i++ ;                                // tells the computer to continue going through the string while "i" is not 0
        
    }
    
    cout << "your string has " << i << " characters" << endl ;
    
    cout << "Your string has " << lowerCase << " lowercase letters." << endl ;   //prints the number of lowercase characters
    
    cout << "Your string has " << num  << " numbers in it." << endl ;       //prints the number of numbers in the string
    
    cout << "Your string has " << upperCase << " uppercase letters." << endl ;  //prints the number of uppercase characters
    
    cout << "Your string has " << spec << " special characters." << endl ;
        return 0 ;
}

What I have tried:

I have tried str[i] != lowerCase str[i] != upperCase etc etc but that just ultimately prints the number of characters in the string.