Introduction

A one-dimensional array is a data type that allows us to allocate a group of similar elements all at once and to give them a single name. For example, the declarations

int A[10];
float nums[15];

/* 
    0  1  2  3  4  5  6  7  8  9
  -------------------------------
A |  |  |  |  |  |  |  |  |  |  |
  -------------------------------

       0  1  2  3  4  5  6  7  8  9 10 11 12 13 14
     ----------------------------------------------
nums |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
     ----------------------------------------------
*/

create an array named A that holds 10 integer variables (numbered 0 to 9) and an array named nums that holds 15 floating-point variables (numbered 0 to 14). Each element of the array A is an integer variable and each element of nums is a floating-point variable. To refer to an individual member of an array we use the square-bracket form. For example A[4] is the element numbered 4 in the array A and nums[10] is the element numbered 10 in the array nums.

Manipulating Arrays

An interesting aspect of arrays is that the number between the square brackets does not have to be a literal constant. We can use any expression that evaluates to an integer value. For example, A[I] would be the element from the array A corresponding to value of the integer variable I (if I is 5, A[I] is the element numbered 5 in A).

We can use this aspect of arrays to write loops that allow us to process ALL of the elements of an array with a single loop. There are two basic types of loops we use to process the elements of an array:

Processing ALL of the elements of an array:

do initital setup

for (I = 0; I < ARRAYSIZE; I++)
  process ARRAYNAME[I]

post process

or

Searching for AN element of an array:

do initial setup

I = 0;

while ((I < ARRAYSIZE) && (ARRAYNAME[I] is not the element we are looking for))
  I++;

if (I < ARRAYSIZE)
  element is found at I
else
  element is not found

In this lab we are going to get some experience with processing an array.

The Program

The following program reads in a group of values using a process all loop. To this program we want to add two processes: (1) a loop to calculate the sum of all the values (in order to produce the average); and (2) a loop to find the first value in the array that is below the average.

#include <stdio.h>
#include <stdlib.h>

void main() {
  int I;
  float nums[15];
  float total = 0.0;
  float average;


  for (I = 0; I < 15; I++) {
    printf("Please enter number %d: ",I+1);
    scanf("%f",&(nums[I]));
  }

  /* Add a loop to sum up all of the numbers in the variable total */



  average = total / 15;

  /* Add a loop to find the first member of the array that has a value
     that is below the average */

}

What to turn in

Turn in a hard copy of your final program. Also, turn in a copy of output for your program showing that it works correctly.