ip地址与int类型的转换
前言最近看道一个面试题目，大体意思就是将ip地址，例如“192.168.1.116”转换成int类型，同时还能在转换回去
思路ip地址转int类型，例如ip为“192.168.1.116”,相当于“.“将ip地址分为了4部分，各部分对应的权值为256^3, 256^2, 256, 1,相成即可
int类型转ip地址，思路类似，除以权值即可，但是有部分字符串的操作
代码
#include <stdio.h>#include <stdlib.h>#include <string.h>#include <math.h>#define LEN 16typedef 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;}