play around with threads

Makefile

@@ -2,11 +2,11 @@ CFLAGS=-std=c99 -Wall -g -O2
 INDENTOPTS=-kr --no-tabs --braces-on-func-def-line --indent-level2
 
 .PHONY: all
-all: approximate-pi linked-list mandelbrot
+all: approximate-pi linked-list mandelbrot threads
 
 .PHONY: clean
 clean:
-	rm -f approximate-pi linked-list mandelbrot *~
+	rm -f approximate-pi linked-list mandelbrot threads *~
 
 .PHONY: indent
 indent:
@@ -14,3 +14,6 @@ indent:
 
 mandelbrot: mandelbrot.c
 	$(CC) $(CFLAGS) $(shell sdl-config --cflags) -o $@ $< $(shell sdl-config --libs) -lm
+
+threads: threads.c
+	$(CC) $(CFLAGS) -o $@ $< -pthread

threads.c

@@ -0,0 +1,47 @@
+#include <stdio.h>
+#include <pthread.h>
+#include <stdlib.h>
+
+#define NUM_THREADS 10
+#define MSG_LEN 100
+
+struct thread_data {
+  char *msg;
+};
+typedef struct thread_data thread_data_t;
+
+void *PrintHello(void *arg) {
+  thread_data_t *td = (thread_data_t *) arg;
+  printf("%s", td->msg);
+  pthread_exit(NULL);
+}
+
+void dienomem() {
+  printf("ERROR: No memory?!\n");
+  exit(1);
+}
+
+int main(int argc, char *argv[]) {
+  pthread_t threads[NUM_THREADS];
+
+  for (int t = 0; t < NUM_THREADS; t++) {
+    /* printf("Creating thread %d\n", t); */
+
+    thread_data_t *td = malloc(sizeof(thread_data_t));
+    if (!td)
+      dienomem();
+    td->msg = malloc(MSG_LEN);
+    if (!td->msg)
+      dienomem();
+
+    snprintf(td->msg, MSG_LEN, "Hello, I'm thread %d!\n", t);
+
+    int rc = pthread_create(&threads[t], NULL, PrintHello, (void *) td);
+    if (rc) {
+      printf("ERROR: return code from pthread_create() is %d\n", rc);
+      exit(1);
+    }
+  }
+
+  pthread_exit(NULL);           /* Wait for the threads to finish. */
+}