How do I check if there is a special character in a string in C++ using isalpha?

Pretty new to coding here. We are working with the isalpha function and I am having trouble using it with a string. My program will prompt the user for a word and then the function will check if the word contains any special characters. Basically, my code will only say there is a special character if they are all special character, not if there is just a couple. I am assuming is has something to do with my for loop but i cannot figure out how to get it to work. I searched quite a bit and can't find much help in C++.

Here is my function. Any help is appreciated.

//*****IsAlphaStr*****
//This function returns true if the cString passed contains all alphabetic characters.
//If the parameter does not contain all alpha characters, a value of false is returned.
bool IsAlphaStr(char wordcheck[25], bool alphabetic)
{
    int i = 0;
    int n = 0;

    for (int i = 0, n = strlen(wordcheck); i < n; i++)
    {   
        if (isalpha(wordcheck[i]) == 0)
            alphabetic = false;
        else
            alphabetic = true;
    }


    return alphabetic;
}

As mentioned, IsAlphaStr shall only return true if all the given characters are alphabetic. This can be achieved by adding a break in the false branch of the if condition, which stops the further execution of the for loop.

        if (isalpha(wordcheck[i]) == 0)
        {
            alphabetic = false;
            break;
        }

The whole test program is:

#include <iostream>

//*****IsAlphaStr*****
//This function returns true if the cString passed contains all alphabetic characters.
//If the parameter does not contain all alpha characters, a value of false is returned.
bool IsAlphaStr(char wordcheck[25], bool alphabetic)
{
    int i = 0;
    int n = 0;

    for (int i = 0, n = strlen(wordcheck); i < n; i++)
    {   
        if (isalpha(wordcheck[i]) == 0)
        {
            alphabetic = false;
            break;
        }
        else
            alphabetic = true;
    }
    return alphabetic;
}

int main()
{
    char test1[25] = "abcdefghijklmnopqrstuvwx";
    char test2[25] = "0123456789ABCDEFGHIJKLMN";
    char test3[25] = "abcdefghijklmnopqres++-A";
    char test4[25] = "abcdefABCDEF";
    bool alphabetic = false;

    alphabetic = IsAlphaStr(test1, alphabetic);
    std::cout << "test1 = " << alphabetic << std::endl;
    alphabetic = IsAlphaStr(test2, alphabetic);
    std::cout << "test2 = " << alphabetic << std::endl;
    alphabetic = IsAlphaStr(test3, alphabetic);
    std::cout << "test3 = " << alphabetic << std::endl;
    alphabetic = IsAlphaStr(test4, alphabetic);
    std::cout << "test4 = " << alphabetic << std::endl;

    return 0;
}

The output is:

test1 = 1
test2 = 0
test3 = 0
test4 = 1

Hope it helps?