I don't understand passing arrays to functions in C

Question

The program I have works. Once I try to clean it up with functions I get totally lost. Can someone please review my code and help me understand what I'm doing wrong?

The program output needs to look like this (please note, this photo was taken prior to adding functions):

Ideally, after the update_level loop, I would then print the totals.

Below is my code with functions that I don't understand at all.

#include <stdio.h>

int update_level(int player[],int healthpoint);
int display_levels();

int main(void)
{
    int levels[6] = {1,2,3,4,5,6};  // levels is an array of 6 integers
    int players[6] = {0,0,0,0,0,0}; // players is an array of 6 integers
    int healthpoints;           // initialize variable
    
    
    printf("Enter total player health points (-1 to quit): ");  // user input
    scanf("%d", &healthpoints);         // reads user input
    
    for(j=0; j<=5; j++)
    {
        update_level(players[j],healthpoints);
    }
    
    return;
}   // end main

int update_level(int player[],int healthpoint);
{
    while (healthpoints != -1)
    {
        if ( healthpoints <= 9)
        {
            players[0] += 1;
        } //end if
        else if (healthpoints <= 19)
        {
            players[1] += 1;
        } //end else if
        else if (healthpoints <= 29)
        {
            players[2] += 1;
        } //end else if
        else if (healthpoints <= 39)
        {
            players[3] += 1;
        } //end else if
        else if (healthpoints <= 49)
        {
            players[4] += 1;
        } //end else if
        else
        {
            players[5] += 1;
        } // end else

        printf("Enter total player health points (-1 to quit): ");  // user input
        scanf("%d", &healthpoints);         // reads user input
        
    }   // end while
    
    return;
}   // end update_level


int display_levels()
{   
    int i;      // initialize variable
    
    printf("T O T A L S\n\n");
    
    for (i = 0; i < 6; ++i){
        printf("Level %u%13d\n", levels[i], players[i]);
    }       // end for
    
    return;
} // end display_levels

Answer 1

With some help, I was able to debug my program. Below is the correct code.

#include <stdio.h>

int update_level(int players[],int healthpoints);
int display_levels(int levels[],int players[]);

int main(void)
{
    int levels[6] = {1,2,3,4,5,6};  // levels is an array of 6 integers
    int players[6] = {0,0,0,0,0,0}; // players is an array of 6 integers
    int healthpoints;           // initialize variable
    
    
    printf("Enter total player health points (-1 to quit): ");  // user input
    scanf("%d", &healthpoints);         // reads user input
    

    update_level(players,healthpoints);
    display_levels(levels,players);

    
    return;
}   // end main

int update_level(int players[],int healthpoints)
{
    while (healthpoints != -1)
    {
        if ( healthpoints <= 9)
        {
            players[0] += 1;
        } //end if
        else if (healthpoints <= 19)
        {
            players[1] += 1;
        } //end else if
        else if (healthpoints <= 29)
        {
            players[2] += 1;
        } //end else if
        else if (healthpoints <= 39)
        {
            players[3] += 1;
        } //end else if
        else if (healthpoints <= 49)
        {
            players[4] += 1;
        } //end else if
        else
        {
            players[5] += 1;
        } // end else

        printf("Enter total player health points (-1 to quit): ");  // user input
        scanf("%d", &healthpoints);         // reads user input
        
    }   // end while
    
    return;
}   // end update_level


int display_levels(int levels[],int players[])
{   
    int i;      // initialize variable
    
    printf("T O T A L S\n\n");
    
    for (i = 0; i < 6; ++i){
        printf("Level %u%13d\n", levels[i], players[i]);
    }       // end for
    
    return;
} // end display_levels