Finding a Value in an Array ```
/* Program FIND_IDX.C
**
** Illustrates function to find the first occurance of a specified value
** in an array.  If the specified value does not exist, function returns
** -1.
**
** Peter H. Anderson, MSU, Feb 21, '97
**
*/

#include <stdio.h>

int find_index(int a[], int num_elements, int value);
void print_array(int a[], int num_elements);

void main(void)
{
int a = {1, 2, 0, 0, 4, 5, 6, 9, 9, 17};
int index, value;

printf("\nArray:\n");
print_array(a, 10);

value = 1;
index = find_index(a, 10, value);
if (index == -1)
{
printf("The value %d was not found.\n", value);
}
else
{
printf("The value %d was found at %d\n", value, index);
}

value = 9;
index = find_index(a, 10, value);
if (index == -1)
{
printf("The value %d was not found.\n", value);
}
else
{
printf("The value %d was found at %d\n", value, index);
}

value = 10;
index = find_index(a, 10, value);
if (index == -1)
{
printf("The value %d was not found.\n", value);
}
else
{
printf("The value %d was found at %d\n", value, index);
}
}

int find_index(int a[], int num_elements, int value)
{
int i;
for (i=0; i<num_elements; i++)
{
if (a[i] == value)
{
return(value);  /* it was found */
}
}
return(-1);  /* if it was not found */
}

void print_array(int a[], int num_elements)
{
int i;
for(i=0; i<num_elements; i++)
{
printf("%d ", a[i]);
}
printf("\n");
}

```