Assignment#1

mm.c

@@ -0,0 +1,95 @@
+#include <stdlib.h>
+#include <stdio.h>
+
+#define debug 0
+
+// Comparison function for qsort()
+int numcmp (const void *a, const void *b) {
+    int x = *((int*) a);
+    int y = *((int*) b);
+    if (x > y) return 1;
+    if (x < y) return -1;
+    return 0;
+}
+
+// function to calculate mean
+float mean(const int* a, int n){
+  float avg =0;
+  int i;
+
+  for(i=0; i<n ; i++)
+    avg += a[i];
+
+  avg /= n;
+
+  return avg;
+}
+
+// function to calculate median
+float median(const int* a, int n){
+  float med = 0;
+
+  if(n % 2 == 0)
+    med = ( a[n/2-1] + a[n/2] ) / 2.0;
+  else
+    med = a[n/2];
+
+  return med;
+}
+
+int main(int argc, char *argv[]) {
+
+    int i, length, *pt;
+
+    // Check for proper usage
+    if (argc < 2) {
+        fprintf(stderr, "%s: Aborting, not enough arguments.\n", argv[0]);
+        return (-1);
+    }
+
+    // Determine amount of numbers from argc
+    length = argc - 1;
+#if debug
+    fprintf(stderr, "%s: DEBUG: %d numbers were passed.\n", argv[0], length);
+#endif
+
+    // Allocate memory for array of number (and error check)
+    if ((pt = malloc(length * sizeof(int))) == NULL) {
+        fprintf(stderr, "%s: Could not allocate memory.\n", argv[0]);
+    }
+
+    // Read numbers into array
+    for (i = 0; i < length; i++) {
+        pt[i] = (int) strtol(argv[i+1], NULL, 10);
+    }
+
+    // Sort numbers
+    qsort(pt, length, sizeof(int), numcmp);
+
+    // Print out numbers
+    fprintf(stdout, "%s: Sorted output is: \n", argv[0]);
+    for (i=0; i<length; i++) {
+        fprintf(stdout, "%d ", pt[i]);
+    }
+
+    fprintf(stdout, "\n");
+    fflush(stdout);
+
+    int rc = fork();
+    float medianVal, meanVal;
+
+    if (rc < 0) { // fork failed; exit
+      fprintf(stderr, "fork failed\n");
+      exit(1);
+    } else if (rc == 0) { //child (new process)
+      medianVal = median(pt, length);
+      fprintf(stdout, "median=%.2f\n", medianVal);
+    } else { // parent goes down this path (main)
+      meanVal = mean(pt, length);
+      fprintf(stdout, "mean=%.2f\n", meanVal);
+      wait(NULL);
+      fprintf(stdout, "\n%s: FIN. \n", argv[0]);
+    }
+
+    return 0;
+}