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mm.c
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mm.c
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#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/wait.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;
}
// Mean() function to calculate the mean
double mean(int *num, int length) {
// Initialize sum
double sum = 0;
// Using a for loop to add all the numbers to sum
for (int i=0; i<length; i++)
sum += num[i];
// Return the mean
return sum/length;
}
// Median() function to calculate the median
double median(int *num, int length) {
// If the array length is even
if (length%2 == 0)
// Return the average of the two median numbers
return (num[length/2-1] + num[length/2]) / 2.0;
// If the array length is odd
else
// Return the median
return num[length/2];
}
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%s: FIN. \n", argv[0]);
// Make fork(), have the parent call mean() and child call median()
int rc = fork();
if (rc < 0) {
fprintf(stderr, "Fork Failed!\n");
exit(0);
} else if (rc == 0) {
// Child call median()
double child = median(pt, length);
// Child process should print the results of median()
fprintf(stdout, "This is child processing (pid:%d)\n", (int)getpid());
fprintf(stdout, "The median value is %f\n", child);
} else if (rc > 0) {
// Parent call mean()
double parent = mean(pt, length);
// Wait for child process
int wc = wait(NULL);
printf("Waiting for child process (wc:%d)\n", wc);
// Parent process should print the results of mean()
fprintf(stdout, "This is parent processing (pid:%d)\n", (int)getpid());
fprintf(stdout, "The mean value is %f\n", parent);
}
return 0;
}