feat: added strdup and putptr

srcs/ft_strdup.c

@@ -0,0 +1,19 @@
+#include "libft.h"
+#include <stdlib.h>
+
+char *ft_strdup(const char *s)
+{
+    size_t len = 0;
+    char *dup;
+    size_t i;
+
+    while (s[len])
+        len++;
+    dup = (char *)malloc(len + 1);
+    if (!dup)
+        return NULL;
+    for (i = 0; i < len; i++)
+        dup[i] = s[i];
+    dup[len] = '\0';
+    return (dup);
+}