Question

我有一个IP地址，例如char *ip = "192.168.1.13"并需要将其转换为此"13.1.168.192" C中是否存在适当的可能性，或者我必须通过简单地制作令牌并将它们再次放在一起来自己完成？

Answer 1

您始终可以使用inet_pton将其转换为二进制格式，以便轻松转换，然后使用inet_ntop转换回文本。

请记住，IPv4地址只是一个32位无符号整数。交换字节周围的字节非常容易。

这样的事情：

const char ip[] = "192.168.0.1";
char reversed_ip[INET_ADDRSTRLEN];

in_addr_t addr;

/* Get the textual address into binary format */
inet_pton(AF_INET, ip, &addr);

/* Reverse the bytes in the binary address */
addr =
    ((addr & 0xff000000) >> 24) |
    ((addr & 0x00ff0000) >>  8) |
    ((addr & 0x0000ff00) <<  8) |
    ((addr & 0x000000ff) << 24);

/* And lastly get a textual representation back again */
inet_ntop(AF_INET, &addr, reversed_ip, sizeof(reversed_ip));

在此代码之后，变量reversed_ip将所提到的地址包含为字符串。

Answer 2

int a,b,c,d;
char *ip = "192.168.1.13"
char ip2[16];
sscanf(ip,"%d.%d.%d.%d",&a,&b,&c,&d);
sprintf(ip2, "%d.%d.%d.%d", d, c, b, a);

Answer 3

#include <stdio.h>
#include <string.h>

void swap(char *a, char *b){
    char wk = *a;
    *a = *b;
    *b = wk;
}

void strpartrev(char *s, int len){
    int i,j;
    for(i=0,j=len-1; i<len/2 ;++i,--j)
        swap(s + i, s + j);
}

char *strwordrev(char *str, char delimiter){
    //str change destructively
    int sp = -1, wordlen=0;
    char stack[16], *p=str;

    while(*p){
        if(*p == delimiter){
            strpartrev(stack + sp - wordlen + 1, wordlen);
            wordlen = 0;
        } else {
            ++wordlen;
        }
        stack[++sp] = *p++;
    }
    strpartrev(stack + sp - wordlen + 1 , wordlen);
    p = str;
    do{
        *p++ = stack[sp--];
    }while(sp>=0);

    return str;
}

char *strWordRev(char *str, char delimiter){
    //str change destructively
    char *head, *tail;
    int len = strlen(str);

    head = str;
    while(tail = strchr(head, delimiter)){
        strpartrev(head, tail - head);
        head = tail + 1;
    }
    strpartrev(head, str + len - head);
    strpartrev(str, len);

    return str;
}

int main(void){
    char *ip = "192.168.1.13";
    char rip[16];

    strcpy(rip, ip);
    printf("%s\n", strWordRev(rip, '.'));//13.1.168.192

    return 0;
}

Answer 4

将ip拆分为数组并使用代码来反转数组。

这是一个整齐的数组，它反转了我在这里找到的代码：http://www.programmingsimplified.com/c-program-reverse-array

#include <stdio.h>

int main()
{
   int n, c, d, a[100], b[100];

   printf("Enter the number of elements in array\n");
   scanf("%d", &n);

   printf("Enter the array elements\n");

   for (c = 0; c < n ; c++)
      scanf("%d", &a[c]);

   /*
    * Copying elements into array b starting from end of array a
    */

   for (c = n - 1, d = 0; c >= 0; c--, d++)
      b[d] = a[c];

   /*
    * Copying reversed array into original.
    * Here we are modifying original array, this is optional.
    */

   for (c = 0; c < n; c++)
      a[c] = b[c];

   printf("Reverse array is\n");

   for (c = 0; c < n; c++)
      printf("%d\n", a[c]);

   return 0;
}

Answer 5

您可以使用addrinfo将字符串转换为getaddrinfo。指定AI_NUMERICHOST以阻止DNS查找。

addrinfo hint;
memset(&hint, 0, sizeof(addrinfo));
hint.ai_socktype = SOCK_STREAM;
hint.ai_protocol = IPPROTO_TCP;
hint.ai_family = AF_INET;
hint.ai_flags = AI_NUMERICHOST; // prevents dns lookup

addrinfo *result = nullptr;
if (getaddrinfo(name, nullptr, &hint, &result))
    return false;

uint32_t ip;
memcpy(&ip, &result, sizeof(uint32_t));

uint32_t ipreversed = htonl(ip);

freeaddrinfo(result);

转换IP以进行反向ip查找

5 个答案: