Day 21: Arrays of Structures | Timers and Interrupts

Lab

const int ButtonInt=0;

const int red=11;

const int yellow=10;

const int green=9;

volatile int selectLED=red;

int lastLED=green;

void setup() {

  pinMode(red,OUTPUT);

  pinMode(yellow,OUTPUT);

  pinMode(green,OUTPUT);

  attachInterrupt(ButtonInt,swap,RISING);

  Serial.begin(9600);

}

void swap()

{

  analogWrite(selectLED,0);

  if(lastLED==red)

  {

    selectLED=yellow;

  }

  else if(lastLED==yellow)

  {

    selectLED=green;

  }

  else if(lastLED==green)

  {

    selectLED=red; 

  }

  lastLED=selectLED;

  Serial.println(selectLED);

}

void loop() {

  for(int i=0; i<256; i++)

  {

    analogWrite(selectLED,i);

    delay(10);

  }

  for(int i=255; i>=0; i--)

  {

    analogWrite(selectLED,i);

    delay(10);

  }

}

Lecture

Arrays of Structures

Notes

• Arrays can contain only single type of information, e.g. array of integers or array of character strings
• If array is needed to store info that contains different types of values, use array of structures

Example 1.1

h[0].name = "Camille";
h[0].year = 1969;
h[0].category = 5;

Example 1.1 shows how to access an individual data member of a structure in an array. The array name, subscript, and data member name must be specified. 

To access an entire structure within the array, the name of the array and a subscript must be specified. 

Example 1.2 
print_hurricane(h[0]);

Example 1.2 would output the following
Hurricane: Camille
Year: 1969
Category: 5

Example 2.1

#include <stdio.h> 
#define FILENAME "storms2.txt" 
/*  Define structure to represent a hurricane.  */ 
struct hurricane 
{ 
char name[10]; 
int year, category; 
}; 
int main(void) 
{ 
/*  Declare variables and function prototype.  */ 
int max_category=0, k=0, npts; 
struct hurricane h[100]; 
FILE *storms; 
void print_hurricane(struct hurricane h); 
/*  Read and print information from the file.  */ 
storms = fopen(FILENAME,"r"); 
if (storms == NULL) 
printf("Error opening data file. \n"); 
else 
{ 
printf("Hurricanes with Maximum Category \n"); 
while (fscanf(storms, "%s %d %d",h[k].name,&h[k].year, 
&h[k].category) == 3) 
{ 
if (h[k].category > max_category) 
max_category = h[k].category; 
k++; 
} 
npts = k; 
for (k=0; k<=npts-1; k++) 
if (h[k].category == max_category) 
print_hurricane(h[k]); 
fclose(storms); 
} 
/*  Exit program   */ 
return 0; 
} 
/*–––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––*/ 
/*  This function prints the hurricane information.            */ 
void print_hurricane(struct hurricane h) 
{ 
printf("Hurricane: %s \n",h.name); 
printf("Year: %d, Category: %d \n",h.year,h.category); 
return; 
}

Problem Solving Example: Tsunamis