declaring an array and defining its length

Arrays example from a Well House Consultants training course
More on Arrays [link]

This example is described in the following article(s):
• New year, new C Course - [link]

Source code: lp.c Module: C205

#include <stdio.h>

/* Arrays, and their length, are declared at compile time in C; you can use the preprocessor to
set up the size as that runs before compile time, and that also avoids the need for the same
constant to be hardcoded right through

If you need to be yet more dynamic, functions such as malloc allow you to grab additional
memory at run time and write a program that's adaptive to the requirements of a particular
run with no hard limits set */

#define YEARS 17

main () {

        int years = YEARS;
        int i;
        float gift;

        float annual[YEARS];

        gift = 200.00;

/* Compound Interest on 200 pound over 17 years, storing results in an array */

        for (i=0; i < years; i++) {
                printf("%d years - %.2f value\n",i,gift);
                annual[i] = gift;
                gift *= 1.05;
        }

        printf("After 7 years - %.2f\n", annual[7]);

/* reusing array to look back and see how much would have had to be invested to make
a certain sum by the end of the period - reusing the stored data */

        for (i=1;i<years;i++) {
                float invest = annual[YEARS-1-i] / annual[YEARS-1] * 100.0;
                printf("Invest %.2f %d years ago\n",invest,i);
                }

}

/* Sample Output

munchkin:c2 grahamellis$ ./lp
0 years - 200.00 value
1 years - 210.00 value
2 years - 220.50 value
3 years - 231.52 value
4 years - 243.10 value
5 years - 255.26 value
6 years - 268.02 value
7 years - 281.42 value
8 years - 295.49 value
9 years - 310.27 value
10 years - 325.78 value
11 years - 342.07 value
12 years - 359.17 value
13 years - 377.13 value
14 years - 395.99 value
15 years - 415.79 value
16 years - 436.57 value
After 7 years - 281.42
Invest 95.24 1 years ago
Invest 90.70 2 years ago
Invest 86.38 3 years ago
Invest 82.27 4 years ago
Invest 78.35 5 years ago
Invest 74.62 6 years ago
Invest 71.07 7 years ago
Invest 67.68 8 years ago
Invest 64.46 9 years ago
Invest 61.39 10 years ago
Invest 58.47 11 years ago
Invest 55.68 12 years ago
Invest 53.03 13 years ago
Invest 50.51 14 years ago
Invest 48.10 15 years ago
Invest 45.81 16 years ago
munchkin:c2 grahamellis$

*/

Learn about this subject

This module and example are covered on the following public courses:
* Learning to Program in C
* Learning to program in C and C++
* Programming in C
* C and C++ Programming
* Learning to program in C and C++
* C and C++ Programming
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