gpio – Control multiple push buttons on a raspberry pi using an mcp23017 over C++

Having followed various tutorials on the web (i.e. 1,2), I have made the following connections:

To enhance clarity, I post another picture depicting the connections on the mpc23017 using a cropped frame from the official datasheet.

Even though wiringPi has been abandoned by the author, I am using this wiringPi – which is fairly maintained by the community. My code is as follows:

#include 
#include 
#include 

int main (){

        wiringPiSetupGpio();
        mcp23017Setup(100, 0x20); //$ sudo i2cdetect -y 1 gives the address 20.

        for (int i = 0; i < 16; ++i){
                pinMode(100 + i, INPUT);
        }

        while( true ){
                for (int i = 0; i < 16; ++i){
                        int sig = digitalRead(100 + i);
                        std::cout<

… but I am getting irrelevant output.

...
0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
...

Therefore, if I may ask,

Do you think the connections are correct? (Especially those on the A0,A1,A2,RESET pins)
Or do you think the error lies on the code?
Other than that, what could be possibly wrong?

image links:
img1
img2