Goofing around with qsort in C

plus making the compiler flags more angry.

digressions/Makefile

@@ -1,8 +1,8 @@
-CFLAGS += -g -Wall -Wextra
+CFLAGS += -g -Wall -Wextra -pedantic -pedantic-errors
 
 %.class:%.java
 	javac -d $(PWD) $^
 
-all: temperatures URLParts.class
+all: temperatures qsort-example URLParts.class
 
 .PHONY: all

digressions/qsort-example.c

@@ -0,0 +1,34 @@
+/*
+ * C Sorting example mostly from qsort(3)
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <libgen.h>
+
+
+static int cmpstringp(const void *p1, const void *p2) {
+    /* The actual arguments to this function are "pointers to
+       pointers to char", but strcmp(3) arguments are "pointers
+       to char", hence the following cast plus dereference */
+
+    return strcmp(*(char * const *)p1, *(char * const *)p2);
+}
+
+
+int main(int argc, char *argv[]) {
+    int j;
+
+    if (argc < 2) {
+        fprintf(stderr, "Usage: %s <string>...\n", basename(argv[0]));
+        exit(EXIT_FAILURE);
+    }
+
+    qsort(&argv[1], argc - 1, sizeof(argv[1]), cmpstringp);
+
+    for (j = 1; j < argc; j++) {
+        puts(argv[j]);
+    }
+
+    exit(EXIT_SUCCESS);
+}