Example code for libc qsort and bsearch

1 files changed, 61 insertions, 0 deletions

diff --git a/src/sort_example.c b/src/sort_example.c
new file mode 100644
index 0000000..7506cde
--- /dev/null
+++ b/src/sort_example.c
@@ -0,0 +1,61 @@
+
+/*
+ * vim:ts=4:sw=4:expandtab
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <stdbool.h>
+#include <stdint.h>
+
+int sort_comp(const void *a, const void *b) {
+    /* casting is dark magic */
+    char * const *A = a;
+    char * const *B = b;
+    return strcmp(*A,*B);
+}
+
+bool search_in_array(char *str, char *array[], size_t items) {
+    char *cptr = NULL;
+
+    printf (" ==> Search for '%s'\n", str);
+    cptr = bsearch(&str, array, items, sizeof(char*), sort_comp);
+
+    return (cptr==NULL) ? false : true ;
+}
+
+int main(void) {
+    char *array[] = {
+        "some", "example", "test", "data", "for", "sort",
+        "and", "search", "duplicate", "data" };
+    size_t items  = sizeof(array)/sizeof(char*) ;
+    size_t i = 0;
+
+    printf(" ==> raw test data\n");
+    for (i=0; i<items; i++) {
+        printf("\t%2lu - %s\n", i, array[i]);
+    }
+
+    printf(" ==> qsort call\n");
+    qsort(array, items, sizeof(char*), sort_comp);
+
+    printf(" ==> sorted test data\n");
+    for (i=0; i<items; i++) {
+        printf("\t%2lu - %s\n", i, array[i]);
+    }
+
+    if (search_in_array("data", array, items)) {
+        printf("\t-> positive hit\n");
+    } else {
+        printf("\t-> not found\n");
+    }
+
+    if (search_in_array("non-existing", array, items)) {
+        printf("\t-> positive hit\n");
+    } else {
+        printf("\t-> not found\n");
+    }
+
+    return EXIT_SUCCESS;
+}