Create str_checksum.cc

new example to illustrate usage of stdx::opt.

1 files changed, 43 insertions, 0 deletions

diff --git a/examples/str_checksum.cc b/examples/str_checksum.cc
new file mode 100644
index 0000000..05cdfd8
--- /dev/null
+++ b/examples/str_checksum.cc
@@ -0,0 +1,43 @@
+/* 
+  string checksum example
+  written by Amlal El Mahrouss.
+  licensed under GPL-2 license
+ */
+
+#include <stdx>
+
+extern "C" {
+#  include <string.h>
+}
+
+static const char do_hash(const char* in)
+{
+  int hash = 0;
+  
+  for (long index = 0; index < strlen(in); ++index)
+  {
+    hash += in[index];
+  }
+
+  return hash;
+}
+
+static auto do_some(const char* recv_data, const char* check_data)
+{
+  const int hash_to_check = do_hash(check_data); /* here we assume this should match opt_hash */
+  const int opt_hash = do_hash(recv_data); /* we assume that the hash is correct */
+  
+  auto opt = stdx::opt(stdx::eval_eq(hash_to_check, opt_hash)); /* do the compute */
+  return opt;
+}
+
+/* finally test it */
+int main(int argc, char** argv)
+{
+  // ... let's assume we fetch data from network...
+  
+  auto opt = do_some("Michigan", "Ohio");
+  opt.expect("Checksum failed, Michigan isn't Ohio!");
+  
+  return 0;
+}