数组上的C ++线性搜索算法

Question

I've started programming using C++ few weeks back. I'm working on an application store user input data into an array list. When entering user data the application must be able to check whether the user already exists in the array list. The program is unable to store the user input or able to check whether the user already exists in the array list..

int linearSearch(int array[], int size, int searchValue)
{
    for (int i = 0; i < size; i++)
    {
        if (searchValue == array[i])
        {
            return i;
            break;
        }
    }

    return -1;
}



void customerReg(){

    const int Capacity = 99;
    int cnic[Capacity];
    int customerNic;                     
    int search = 0;

    cout << "Enter Customer NIC: \n";
    cin >> cnic[Capacity];


    search = linearSearch(cnic, Capacity, customerNic);

    if (search != -1){
        cout << "Customer is already registered!\n";
    }

    else {
        string customerName;
        cout << "Enter Customer Name: \n";
        cin >> customerName;

    }

Answer 1

What about:

...
cout << "Enter Customer NIC: \n";
cin >> customerNic;    // <=== instead of: cnic[Capacity];

Other remarks:

• the break is not necessary: the return will already interupt the search loop
• cnic[Capacity] is out of range, so puting a value in it might cause some troubles
• cnic[] is not initialised
• It is not clear how you fill cnic[] , which is by the way local to the function and be lost as soon as you return from it.
• Depending how you initalize/fill cnic , it could make sense to keep track of the number of customers that are registered in the table.

Edit:

I assume that you can't use vectors or maps for your exercise, and that you're right at the beginning of your learning.

So I suppose that customerReg() is the first function that you are working on, and that others will follow (display, delete, modifiy...). If this is the case, you have to keep your customer data outside the functions:

const int Capacity = 99;
int cnic[Capacity] {}; 
int customer_count=0;    // counter to the last customer inserted

Then in customerReg() you should call your search function using the number of customers instead of the maximal Capacity :

search = linearSearch(cnic, customer_count, customerNic);

Later, in the else branch you have to insert the new id into the array:

else {
    if (customer_count==Capacity) {
       cout << "Oops ! Reached max capacity"<<endl; 
    else { 
       string customerName;
       cout << "Enter Customer Name: \n";
       cin >> customerName;
       ... 
       cnic[customer_count] = customerNic; // here you store the id
       ... // store (I don't know where) the other customer elements you've asked for 
       customer_count++;  // increment the number of users that are stored. 
    }
}