Add back function to vectors

back() returns the element in the last position without removing it.

3 files changed, 35 insertions, 1 deletions

diff --git a/collections/vector/vector.adoc b/collections/vector/vector.adoc
index 3fe2dbf..d439c85 100644
--- a/collections/vector/vector.adoc
+++ b/collections/vector/vector.adoc
@@ -1,7 +1,7 @@
 Vector
 ======
 Tucker Evans
-v0.8.1, 2020-07-03
+v0.9, 2020-07-03
 
 A basic vector, that hold pointers to your data structures.
 
@@ -186,6 +186,29 @@ assert(str_cmp(vec_pop(vector), str2) == 0);
 assert(str_cmp(vec_pop(vector), str1) == 0);
 ----
 
+[[vec_back]]
++void* vec_back(vec *self)+
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Returns the element at the back of the vector +self+.
+
+Examples
+^^^^^^^^
+[source,c]
+----
+#include "vector.h"
+#include <string.h>
+
+char *str1 = "ONE";
+char *str2 = "TWO";
+
+vec *vector = vec_new();
+vec_push(vector, str_dup(str1));
+vec_push(vector, str_dup(str2));
+
+assert(strcmp(vec_back(vector), str2) == 0);
+----
+
+
 [[vec_index]]
 +void* vec_index(vec *self, int index)+
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
diff --git a/collections/vector/vector.c b/collections/vector/vector.c
index b8f83de..0b816b7 100644
--- a/collections/vector/vector.c
+++ b/collections/vector/vector.c
@@ -142,6 +142,16 @@ vec *root;
 	return root->base[--root->end];
 }
 
+void* vec_back(root)
+vec *root;
+{
+	if (!root || root->end == 0) {
+		return NULL;
+	}
+
+	return root->base[root->end - 1];
+}
+
 void* vec_index(root, index)
 vec *root;
 int index;
diff --git a/collections/vector/vector.h b/collections/vector/vector.h
index 4bcb620..f1eea64 100644
--- a/collections/vector/vector.h
+++ b/collections/vector/vector.h
@@ -16,6 +16,7 @@ void vec_print(vec*, char* (void*));
 /*data*/
 void vec_push(vec*, void*);
 void* vec_pop(vec*);
+void* vec_back(vec*);
 
 void* vec_index(vec*, int);