How to get value of optarg without using command line? - c++

Question

I used getopt() function to get value of optarg parameters in Visual Studio. However, following to document of GNU, getopt() is a function that used to parse command-line options of the Unix/POSIX style and I can not use commandline in Visual Studio. So, how can I get the optarg in VS without using command line or getopt().
Here is my code:
int ch;
extern char* optarg;/*
extern int optind, opterr;*/
char* testfn;
bool testflag = false;
double prd = 60 * 24; // minutes of a day
int maxstep = 100; // # em steps
int Z = 2; // # mixtures
double initscale = 0.25 * prd; // 6 hours
while (optind < argc) {
if ((ch = getopt(argc, argv, "t:m:z:s:")) != -1) {
switch (ch) {
case 't':
testflag = true;
testfn = optarg;
break;
case 'm':
maxstep = atoi(optarg);
break;
case 'z':
Z = atoi(optarg);
break;
case 's':
initscale = atof(optarg);
break;
default:
usage();
}
}
else {
// Regular argument
//code to handle the argument
optind++; // Skip to the next argument
}
}