C/C++ ip地址与int类型的转换实例详解

#include <stdio.h> #include <stdlib.h> #include <string.h> #include <math.h>  #define LEN 16  typedef unsigned int uint;  /**  * 字符串转整形  */ uint ipTint(char *ipstr) {   if (ipstr == NULL) return 0;    char *token;   uint i = 3, total = 0, cur;    token = strtok(ipstr, ".");    while (token != NULL) {     cur = atoi(token);     if (cur >= 0 && cur <= 255) {       total += cur * pow(256, i);     }     i --;     token = strtok(NULL, ".");   }    return total; }  /**  * 逆置字符串  */ void swapStr(char *str, int begin, int end) {   int i, j;    for (i = begin, j = end; i <= j; i ++, j --) {     if (str[i] != str[j]) {       str[i] = str[i] ^ str[j];       str[j] = str[i] ^ str[j];       str[i] = str[i] ^ str[j];     }   } }  /**  * 整形转ip字符串  */ char* ipTstr(uint ipint) {   char *new = (char *)malloc(LEN);   memset(new, '/0', LEN);   new[0] = '.';   char token[4];   int bt, ed, len, cur;    while (ipint) {     cur = ipint % 256;     sprintf(token, "%d", cur);     strcat(new, token);     ipint /= 256;     if (ipint) strcat(new, ".");   }    len = strlen(new);   swapStr(new, 0, len - 1);    for (bt = ed = 0; ed < len;) {     while (ed < len && new[ed] != '.') {       ed ++;     }     swapStr(new, bt, ed - 1);     ed += 1;     bt = ed;   }    new[len - 1] = '/0';    return new; }  int main(void) {   char ipstr[LEN], *new;   uint ipint;    while (scanf("%s", ipstr) != EOF) {     ipint = ipTint(ipstr);     printf("%u/n", ipint);      new = ipTstr(ipint);     printf("%s/n", new);   }    return 0; }