IsNummeric

stock IsNumeric(const string[]) {
    new length=strlen(string);
    if (length==0) return false;
    for (new i = 0; i < length; i++) {
        if (
        (string[i] > '9' || string[i] < '0' && string[i]!='-' && string[i]!='+')
        || (string[i]=='-' && i!=0)                                             //
        || (string[i]=='+' && i!=0)                                             //
        ) return false;
    }
    if (length==1 && (string[0]=='-' || string[0]=='+')) return false;
    return true;
}