Problem with boolean search function.

[DukeNukemBOS]

I am currently writing a program for an assignment in data structures class. The assignment says "Write a program that
fills a 5 x 5 matrix of integers. The matrix must be a static matrix; its size must be fixed at
compile-time. Display the contents of the matrix. Query the user for an integer. Pass the matrix
and the integer to a bool function that searches for the first occurrence of the integer in the
matrix. If the integer is found, the function returns true (and passes back the row and column
coordinates of the first occurrence of the integer); if not, the function returns false. Main then
displays whether the integer was found in the matrix and if so, the coordinates of the first
occurrence. The use of break to exit a loop or a function should be avoid and will be penalized." Here is the code I have written so far.

#include <iostream>
#include <stdlib.h>
#include <ctime>
using namespace std;

int main(int argc, char const *argv[])
{
    //Seed random function to generate numbers for matrix
    srand(time(0));
    int a[5][5], i , j, n, found = 0;
    //Generates random numbers for matrix
    for (i = 0; i < 5; i++)
    {      
         for ( j = 0; j < 5; j++)
        {
            a[i][j]= rand() % 100 + 1;
        }
        
    } //Loop that prints numbers until it reaches 5 columns and 5 rows
    for ( i = 0; i < 5; i++)
    {
        for ( j = 0; j < 5; j++)
        {
            cout << a[i][j]<< '\t';
            
        }
        cout << '\n';
        
   }
    //Boolean function to find number in matrix
    bool search;
        {  
            cout << "Enter the integer you want to search: ";
            cin >> n;
            if (a[i][j] == n)
            {
                found = 1;
            }
            if (found == 1)
            {
                cout << "Integer found at (" << i << "," << j << ")";
            }
            else
            {
                cout << "Integer could not be found";
            }
                        
            

        }
        
    return 0;

}    

The program runs fine except when searching for a value in the matrix. When I input a number even if it's in the matrix. It gives me a integer not found. Any ideas what I could have done wrong? I am still new to C++

[Manga]

#include <iostream>
#include <stdlib.h>
#include <ctime>
using namespace std;

//Boolean function to find number in matrix
bool search(int a[][5]) {
    int n, i, j;
    cout << "Enter the integer you want to search: ";
            cin >> n;
            
            for (i = 0; i < 5; i++)
              {      
                for ( j = 0; j < 5; j++)
                {
                  if (a[i][j] == n)
                   {
                   cout << "Integer found at (" << i << "," << j << ")";
                   return true;
                   }
                }
        
              }
    cout << "Integer could not be found";
    return false;      
}



int main(int argc, char const *argv[])
{
    //Seed random function to generate numbers for matrix
    srand(time(0));
    int a[5][5],i ,j;
    //Generates random numbers for matrix
    for (i = 0; i < 5; i++)
    {      
         for ( j = 0; j < 5; j++)
        {
            a[i][j]= rand() % 100 + 1;
        }
        
    } //Loop that prints numbers until it reaches 5 columns and 5 rows
    for ( i = 0; i < 5; i++)
    {
        for ( j = 0; j < 5; j++)
        {
            cout << a[i][j]<< '\t';
            
        }
        cout << '\n';
        
   }
    //Boolean function call
    search(a);
        
        
    return 0;

}  

[DukeNukemBOS]

Thank you for your help. The program finally works. I guess I didn't know that I had to put the boolean function outside of main.

[Ganado]

You didn't have to create a separate function, it just helps a lot with readability and expresses intent.

Your actual issue was due to two things:

(1) You declared i and j in the full function scope, so at the end of your nested for loops after line 29 of your original post, i = 5 and j = 5, which are out-of-bounds indices for your array.

This would be prevented if you declared your variables in the narrowest scope possible,

    for (int i = 0; i < 5; i++)
    {
        for (int j = 0; j < 5; j++)
        {
            cout << a[i][j]<< '\t';
            
        }

(2)

            cout << "Enter the integer you want to search: ";
            cin >> n;
            if (a[i][j] == n)
            {
                found = 1;
            }
            if (found == 1)
            {
                cout << "Integer found at (" << i << "," << j << ")";
            }
            else
            {
                cout << "Integer could not be found";
            }

You only check a single array element here, a[i][j]. You aren't looping through every element to see if at least one element matches.

[Manga]

Also the way you used the if else combo... You made one search and if it did not match that first search the else statement took over. Which even with a loop would have caused a problem. So I took the 'else' out of it. One more thing... the bool function returns a value, either true or false. I did not store that value anywhere, so it is a lost value that is not used.

[jlb]

But as you noted, you can not create functions inside of other functions in C++.