Emphasize size_t length for %b formatting

Closes #121.

README.md

@@ -68,7 +68,7 @@ When you need to pass binary safe strings in a command, the `%b` specifier can b
 used. Together with a pointer to the string, it requires a `size_t` length argument
 of the string:
 
-    reply = redisCommand(context, "SET foo %b", value, valuelen);
+    reply = redisCommand(context, "SET foo %b", value, (size_t) valuelen);
 
 Internally, Hiredis splits the command in different arguments and will
 convert it to the protocol used to communicate with Redis.

examples/example.c

@@ -32,7 +32,7 @@ int main(void) {
     freeReplyObject(reply);
 
     /* Set a key using binary safe API */
-    reply = redisCommand(c,"SET %b %b", "bar", 3, "hello", 5);
+    reply = redisCommand(c,"SET %b %b", "bar", (size_t) 3, "hello", (size_t) 5);
     printf("SET (binary API): %s\n", reply->str);
     freeReplyObject(reply);
 

hiredis.c

@@ -917,7 +917,7 @@ err:
  * %b represents a binary safe string
  *
  * When using %b you need to provide both the pointer to the string
- * and the length in bytes. Examples:
+ * and the length in bytes as a size_t. Examples:
  *
  * len = redisFormatCommand(target, "GET %s", mykey);
  * len = redisFormatCommand(target, "SET %s %b", mykey, myval, myvallen);

test.c

@@ -130,13 +130,13 @@ static void test_format_commands(void) {
     free(cmd);
 
     test("Format command with %%b string interpolation: ");
-    len = redisFormatCommand(&cmd,"SET %b %b","foo",3,"b\0r",3);
+    len = redisFormatCommand(&cmd,"SET %b %b","foo",(size_t)3,"b\0r",(size_t)3);
     test_cond(strncmp(cmd,"*3\r\n$3\r\nSET\r\n$3\r\nfoo\r\n$3\r\nb\0r\r\n",len) == 0 &&
         len == 4+4+(3+2)+4+(3+2)+4+(3+2));
     free(cmd);
 
     test("Format command with %%b and an empty string: ");
-    len = redisFormatCommand(&cmd,"SET %b %b","foo",3,"",0);
+    len = redisFormatCommand(&cmd,"SET %b %b","foo",(size_t)3,"",(size_t)0);
     test_cond(strncmp(cmd,"*3\r\n$3\r\nSET\r\n$3\r\nfoo\r\n$0\r\n\r\n",len) == 0 &&
         len == 4+4+(3+2)+4+(3+2)+4+(0+2));
     free(cmd);
@@ -182,7 +182,7 @@ static void test_format_commands(void) {
     FLOAT_WIDTH_TEST(double);
 
     test("Format command with invalid printf format: ");
-    len = redisFormatCommand(&cmd,"key:%08p %b",(void*)1234,"foo",3);
+    len = redisFormatCommand(&cmd,"key:%08p %b",(void*)1234,"foo",(size_t)3);
     test_cond(len == -1);
 
     const char *argv[3];
@@ -335,7 +335,7 @@ static void test_blocking_connection(struct config config) {
     freeReplyObject(reply);
 
     test("%%b String interpolation works: ");
-    reply = redisCommand(c,"SET %b %b","foo",3,"hello\x00world",11);
+    reply = redisCommand(c,"SET %b %b","foo",(size_t)3,"hello\x00world",(size_t)11);
     freeReplyObject(reply);
     reply = redisCommand(c,"GET foo");
     test_cond(reply->type == REDIS_REPLY_STRING &&