求字符串的有效字符的个数

#include
#include //调用库函数strlen,
//求字符串的有效长度
int mystrlen(const char *src)
{
 int count=0;
 while(*src!=0)
 {
  count ++;
  src++;
 }
 return count;
}
int main()
{
 char str1[100] = "abcdef";
 char *str2 = "abcdef";
 char str3[] = "abcdef";
 char str4[100] = "abcde\0fgh";
 char str5[] = "abcde\0fgh";
 char *str6 = "abcde\0fgh";
 printf("%d,%d\n",sizeof(str1),strlen(str1));//100,6
 printf("%d,%d\n",sizeof(str2),strlen(str2));//4,6
 printf("%d,%d\n",sizeof(str2),mystrlen(str2));//4,6
 printf("%d,%d\n",sizeof(str3),strlen(str3));//7,6
 printf("%d,%d\n",sizeof(str4),strlen(str4));//100,5
 printf("%d,%d\n",sizeof(str5),strlen(str5));//10,5
 printf("%d,%d\n",sizeof(str6),strlen(str6));//4,5
 printf("%d\n",strlen("*&^%43@! ][")); //11
 printf("%d\n",mystrlen("*&^%43@! ][")); //11
 printf("%d\n",mystrlen("56123dhkj")); //9
 return 0;
}