Variable not declared within this scope Array Linear Search

Question

I am trying to make a program in C++ that will search for a desired value in an array of size 10 using a separate search function. Below is the code:

main.cpp

#include <iostream>   
#include <array>   
using namespace std;

int main()  
{
    cout << "Welcome to the array linked list program.";

    int sanadA[] = {2, 4, 6, 8, 10, 12, 14, 16, 18, 20};
    int d = 0;
    cin >> d;
    while (d =! 0)
    {
        cout << "Number to be found";
        cin >> d;
        bool found = seqSearch1(sanadA, 10, d, -1);
        cout << found;
    }
}

seqSearch1.cpp

#include <iostream>
using namespace std;

bool jw_search (int *list, int size, int key, int*& rec)
{ //Basic sequential search.
    bool found = false;
    int i;

    for(i=0;i<size;i++)
    {
        if (key == list[i])
        {
            break;
        }
        if (i < size)
        {
            found = true;
            rec = &list[i];
        }
    }
    return found;
}

I get the errors:

C:\Users\tevin\Documents\sanad\main.cpp|13|warning: suggest parentheses around assignment used as truth value [-Wparentheses]|

C:\Program Files (x86)\CodeBlocks\MinGW\lib\gcc\mingw32\5.1.0\include\c++\bits\c++0x_warning.h|32|error: #error This file requires compiler and library support for the ISO C++ 2011 standard. This support is currently experimental, and must be enabled with the -std=c++11 or -std=gnu++11 compiler options.|

C:\Users\tevin\Documents\sanad\main.cpp|19|error: 'seqSearch1' was not declared in this scope|

I need help figuring why this happens.

Answer 1

I assume that the error occurs on this line:

bool found = seqSearch1(sanadA, 10, d, -1);

The problem is that you have not declared any function named seqSearch1(). Instead you have a function named jw_search(). So you can change the line to this:

bool found = jw_search(sanadA, 10, d, -1);

But you also need a header file called seqSearch1.h with the following line:

bool jw_search (int *list, int size, int key, int*& rec);

And finally add this line to the top of main.cpp:

#include "seqSearch1.h"

When you compile your code, you will need to include all source files in the command. For example, if you are using g++, you can do something like this:

g++ main.cpp seqSearch1.cpp

To understand how this works, you need to learn about header files and the difference between a function declaration and a function definition. You should also learn about the difference between the compiler and the linker.

Answer 2

Code-Apprentice has the direct answer to your question. If you want the code in multiple files then a declaration of the seqSearch1 function will need to be main.cpp or included via #include directive

The code has multiple problems. I've fixed it up a bit for you and put it in a single file.

#include <iostream>

#include <array>
using namespace std;

bool seqSearch1 (int *list, int size, int key, int& rec)
{//Basic sequential search.
bool found = false;

int i;

for(i=0;i<size;i++)
{
    if (key == list[i])
    {
        found = true;
        rec = i;
        break;
    }
}
return found;
}

int main()
{
     cout << "Welcome to the array linked list program." << endl;

int sanadA[] = {2, 4, 6, 8, 10, 12, 14, 16, 18, 20};
int d = -1;
while (d != 0)
{
    cout << "Number to be found, 0 to end?";
    cin >> d;
    if(d == 0) break;
    int index = -1;
    bool found = seqSearch1(sanadA, 10, d, index);
    if(found) cout << "Found" << endl;
    else  cout << "Not Found" << endl;
}
}

Several issues:

1. The function was referred to by the wrong name.
2. The loop structure was a confused.
3. The fourth argument to seqSearch1 had type confusion.