//1、memchr函数，字符定位。  Locate character in block of memory
// void * memchr ( const void *, int, size_t );
    char * pch;
    char str[] = "Example string";
    pch =(char *) memchr(str,'p',strlen(str));  //返回的指针
    if(pch != NULL){ //找不到，返回NULL
        cout<<pch<<endl;  //            《《输出：  ple string
        cout<<"'p'在位置："<<pch-str+1; //《《输出： 'p'在位置：5
//指针在加减运算后，输出为数字 （下标）
    }

    char str1[256];
    char str2[256];
    int n;
    gets(str1); //gao
    gets(str2);//tong
    n = memcmp(str1, str2, 256);  //256为比较的字节数，一个字符占一byte
    cout<<n<<endl;  //输出：-1
    return 0;

    char str1[]="Sample string";
      char str2[40];
      char str3[40];
      memcpy (str2,str1,strlen(str1)+1);  //strlen(str1)+1，因为字符串后面有'\0'
      memcpy (str3,"copy successful",16);
      printf ("str1: %s\nstr2: %s\nstr3: %s\n",str1,str2,str3);

//      输出：
//      str1: Sample string
//      str2: Sample string
//      str3: copy successful

//memmove函数 Move block of memory
char str[] = "gao love tong";
char * p;
p = (char *)memmove(str+9, str+4,4); //
cout<<str<<endl<<p; 

//输出：
// gao love love
// love

    char str[] = "almost every programmer should know memset!";
    memset(str,'-',6);  //'-'直接转换为数字存储，6是字节数
    cout<<str;  //输出：------ every programmer should know memset!

    char str[] = "this is a sample string";
char * pch;
    pch = strchr(str, 's');
while(pch != NULL){
        cout<<"found at:"<<pch-str+1<<enl; //输出找到的字符下标
        pch = strchr(pch+1,'s'); //
    }

found at:4
found at:7
found at:11
found at:18

    char * c1;
char * c2;
    c1 = "abd";
    c2 = "abcde";
    cout<<strcmp(c1,c2);

char str[] = "This is a sample string";
char key[] = "aeiou";
char * pch;
  printf ("Vowels in '%s': ",str);
  pch = strpbrk (str, key);
while (pch != NULL)
  {
    printf ("%c " , *pch);
    pch = strpbrk (pch+1,key);
  }
  printf ("\n");

output:

Vowels in 'This is a sample string': i i a a e i