Diff: main.cpp

Revision:

116:518fcfbba05c

Parent:

115:f22cbbc92bae

Child:

117:b40379408898

--- a/main.cpp	Wed Oct 13 14:27:35 2021 +0000
+++ b/main.cpp	Thu Oct 14 15:11:03 2021 +0000
@@ -1,35 +1,62 @@
 /*
-Project: 21_ConsoleIO_v5
-File: main.cpp
-
- This simple program demonstrates that C passes arguments by value.
+ Program 8.3 Calculating an average using functions.
+ from Horton's Beginning C, 5th ed.
 
- Uses VT-100 escape sequences to prevent scrolling. See
- http://www.csie.ntu.edu.tw/~r92094/c++/VT100.html and/or
- https://gist.github.com/fnky/458719343aabd01cfb17a3a4f7296797.
+ Note isolation of user input in main and a single function.
 
- Written by: Dr. C. S. Tritt; Last revised 10/11/21 (v. 1.1)
+ Ported to mbed by C. S. Tritt
+ Last revised: 10/5/17 (v. 1.1)
 */
 #include "mbed.h"
 
-int main()
-{
-    const int DELAY = 2000000;; // mS wait time.
-    const char ESC = 27; // Define escape character for escape sequence.
-    printf("%c[2J%c[H", ESC, ESC); // ANSI/VT100 clear screen/home.
+const int MAX_COUNT=10; // Set input limit. Protects against buffer overrun.
+
+// Function prototypes...
+float Sum(float x[], int size); // Sums the values in a float array.
+float Average(float x[], int size); // Averages the values in a float array.
+int GetData(float *data, int max_count); // Gets data from std Serial.
+
+// main program - execution starts here.
+int main(void) {
+    float samples[MAX_COUNT] = {0.0};  // Create array for samples.
+    int sampleCount = GetData(samples, MAX_COUNT); // Get values.
+    float average = Average(samples, sampleCount); // Find average.
+    // Display results.
+    printf("The average of the values you entered is: %.2f.\n", average);
+    return 0;
+}
+
+// Function to calculate the sum of array elements. n is the number of elements
+// in array x.
+float Sum(float x[], int size) {
+    float sum = 0.0;
+    for(int i = 0 ; i < size ; ++i) sum += x[i];
+    return sum;
+}
 
-    // Replace the code below with your code.
-    int count = 1; // Declared in outer block.
-    int iCount = 0; // This is another variable called count.
-    do {
-        --iCount; // this applies to inner count.
-        printf("Count Down = %d and abs(Count Down) = %d\n", 
-            iCount, abs(iCount));
-    } while( ++count <= 5); // This works with outer count.
+// Function to calculate the average of array elements. Calls Sum.
+float Average(float x[], int size) {
+    return Sum(x, size)/size;
+}
 
-    printf("count = %d\n", count); // Inner count is dead.
-
-    while(true) {  // Main forever loop.
-        ThisThread::sleep_for(DELAY); // Pause
+// Function to read in data items and store in data array. The function returns
+// the number of items stored.
+int GetData(float *data, int max_size) {
+    int nValues = 0;
+    // Clear screen & move cursor to upper left ANSI/VT100 sequence.
+    const char ESC=27; printf("%c[2J", ESC); printf("%c[H", ESC);
+    printf("Assure Local Echo is activated!\n");
+    printf("Number of values to average (Maximum %d)? ", max_size);
+    scanf("%d", &nValues);
+    printf("%d was read.\n", nValues); // added by cst.
+    if(nValues > max_size) {
+        printf("Maximum count exceeded. %d items will be read.", max_size);
+        nValues = max_size;
     }
+    printf("Enter values:\n");
+    for( int i = 0 ; i < nValues ; ++i) {
+        scanf("%f", &data[i]);
+        printf("%f was read.\n", data[i]); // added by cst.
+    }
+    return nValues;
 }
\ No newline at end of file