C + + to ask for the first occurrence of a string character __c++

Asks for the first occurrence of a character in a string.
#include <iostream>
#include <string.h>
#define _SIZE_ 255
using namespace std;

struct Node
{
    int index;//store subscript.
    int num;//storage number.
    Node (): Index ( -1), num (0) {}
};
Char grial (char *str)
{
    Node node[_size_];//does not require so much space if only 26 characters are considered.
    int slen = strlen (str);
    int i = 0;
    int mix = 0x7fffffff;
    for (; i < slen; i++)
    {
        Node[str[i]].index = i;//subscript save.
        number of node[str[i]].num++;//saved.
    }
    for (i = 0; i < _size_ i++)
    {
        if (Node[i].num = 1)
        {
            mix = Mix>node[i].index? Node[i].index: Mix;
            Find the subscript that appears only once for the first time.
        }
    }
    return Str[mix];
    The total time complexity is n (iterate through) +m (total number of occurrences).
    //Space complexity, which opens up a set of additional node space to store the data.
}
int main ()
{
    char *p = ' 1222345678234543 ';
    Cout<<grial (p) <<endl;
    return 0;
}