KEILC51程序实例和配套硬件目标板,很详细,程序有注释

				#include 
				#include                   /* for printf */
				void tst_strlen (void) {
				   char buf [] = "Find the length of this string";
				   int len;
				   len = strlen (buf);
				   printf ("string length is %d\n", len);
				}