Is this the right way to loop through Arrays? - c++

Question

#include <iostream>
#include <Windows.h>
#include <string>
using namespace std;
int main(){
string Whitelist[4] = {"Stian", "Mathias", "Modaser"};
for (int x = 0; x < 3; x++){
cout << x + 1<< ". " << Whitelist[x] << endl;
if (Whitelist[x] == "Stian" && "Mathias" && "Modaser"){
cout << "" << Whitelist[x] << " is here" << endl;
}
else{ cout << "no one is here" << endl; }
}
cin.get();
return 0;
}
//so yeah basically im just trying to loop through my array and see if any of these names are there. so i guess u can pretty much read what the code does since most of u are pros :P. but when i asked my friend, whos been coding for 1-2 years, he said that i couldnt loop through arrays like this and told me to use a vector. what does he mean by that? and my code works?

Answer 1

This set of code is wrong
if (Whitelist[x] == "Stian" && "Mathias" && "Modaser"){
cout << "" << Whitelist[x] << " is here" << endl;
}
Why? because suppose the first condition of the if statement evaluates to true like this:
if (true && "Mathias" && "Modaser")
{
//...
}
Then the code wouldn't make sense. In an if statement, you have to check for every condition separately, like this:
if (Whitelist[x] == "Stian" && Whitelist[x] =="Mathias" && Whitelist[x] =="Modaser"){
cout << "" << Whitelist[x] << " is here" << endl;
}
But since any 1 string cannot be three names at the same time, this condition will fail, (you used &&). Fix your code using the || operator, like this, for your final code (Also, remove << "", that is just redundant, and unnecessary):
if (Whitelist[x] == "Stian" || Whitelist[x] =="Mathias" || Whitelist[x] =="Modaser"){
cout << Whitelist[x] << " is here" << endl;
}
BTW: As a recommendation, use a std::vector<std::string>, not a raw array, so you get easier and more capabilities than an array.
Lastly, you also have 4 elements in your array, of which one is unused. It might be a typo, so make your array size 3.

Answer 2

There is nothing fundamentally wrong with looping over an array like this.
We can only guess what your friend meant, but I can perform my own review of your code.
However, you have four array elements and only loop over three of them, which may be a mistake; if it is, it's evidence that you'd be better off using iterators, rather than hard-coding numbers that you can get wrong.
Furthermore, your if conditional is wrong: did you mean || ("or"), instead of && ("and")? And you have to write out the adjoined conditions in full, so:
if (Whitelist[x] == "Stian" || Whitelist[x] =="Mathias" || Whitelist[x] =="Modaser")
I'm not sure why you're comparing against all these values, when they're the only ones in the array. Well, except for that empty fourth element; perhaps you're trying to catch that. We don't know, because you didn't tell us. Did you mean to search Whitelist while iterating over some other array? We have no way of knowing. Maybe that's what your friend really meant? Again, I couldn't say.
Streaming "" to std::cout just waits resources and does literally nothing else. Remove it.
Finally, and somewhat tangentially, it would be better not to block waiting for input as a means to keep your console window open. That is not your program's job.