Whats is the equivalent way to strcpy in C#

[Adrianos01]

I want to write a C++ function in C#:

the C++ code:

#define deleter "/.:_-";
char code[25]; // SR2342-23422-234234

int take_mod(char *number,int anz,int position)
{
    int k=0,n=0;
 
    while (zahl[n]!=0)
    {              
         k=(int)number[n];
#ifdef blank
        if ((strchr(deleter,k) !=0) || (!isdigit(number[n])))
        {
#ifdef delete_blank
            strcpy(number+n,number+n+1);
#else
            n++;
#endif
            continue;
        }
}

C# code:

 public int take_mod(string number, int anz, int position) {
            int i = 0, k = 0,  n = 0 , u = 0;
            char numberValue;
 
            while (number[n] != 0) {
                k = number[n];
                numberValue= number[n];
#if deleter
                if ((number.IndexOf(deleter[u]) != 0) || (!Char.IsDigit(numberValue))) {
#if delet_blanks
                    number = number[n + 1].ToString();
#else  
                n++;
                u++; // u ++ ?????????????
#endif
                continue;
                }
#endif
}

I want to run the 24 x characters (SR2342-23422-234234) and delete the alphanumerics and blanks.

thx?