How to get paths defined in the system environment

char path[_MAX_PATH];

const char* varName = "[system environment variable name]";
size_t len;
getenv_s(&len, path, 80, varName);

Print out a (decimal) number as a hexadecimal number

int decNum = 123456;
char hexNum[16];

// decimal number to hexadecimal number
sprintf_s(hexNum, 16, "%X", decNum);
printf("%d -> %s \n", decNum, hexNum);

// hexadecimal number to decimal number
sprintf_s(hexNum, 16, "FF");
decNum = (int)strtol(hexNum, nullptr, 16);
printf(" %s -> %d \n", hexNum, decNum);