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Copy pathipToNum.cpp
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executable file
·113 lines (103 loc) · 2.59 KB
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/*
@filename ipToNum.cpp
@author caonan
@date 2022-04-28 12:21:18
@reference 个人收集
@url
@brief 将字符串类型的点分十进制IPv4转换为无符号整数
*/
#include <arpa/inet.h>
#include <assert.h>
#include <stdio.h>
#include <algorithm>
#include <bitset>
#include <deque>
#include <iostream>
#include <map>
#include <queue>
#include <stack>
#include <unordered_map>
#include <vector>
using namespace std;
/*
首先需要理解IP地址可以用4个字节表示，每个字节代表一段
需要注意IP地址每段最大为255，故需要用无符号整数表示
遍历一次即可完成，每段转换为10进制数字，一次点分左移8位或乘以255；最后一段也需要加上
如果有IP地址合法性检查加分
*/
unsigned int ipToNum(string ip) {
vector<int> ip_arr;
int pos = 0;
while (true) {
int pre = pos;
pos = ip.find('.', pos);
if (pos == std::string::npos) {
ip_arr.push_back(std::stoi(ip.substr(pre)));
break;
}
pos++;
ip_arr.push_back(std::stoi(ip.substr(pre, pos - pre)));
}
string number;
for (auto n : ip_arr) {
bitset<8> b(n);
// 主机序
number += b.to_string();
}
bitset<32> ans(number);
return ans.to_ullong();
}
// 优化版本
unsigned int ipToNum2(string ip) {
int num = 0;
int left_offset = 3;
unsigned int total_num = 0;
ip += ".";
for (int i = 0; i < ip.length(); i++) {
if (ip[i] != '.') {
int n = ip[i] - '0';
num = num * 10 + n;
continue;
}
total_num = total_num == 0 ? num : total_num + num;
total_num = left_offset-- > 0 ? total_num << 8 : total_num;
num = 0;
}
return total_num;
}
uint32_t check(string ip) {
struct in_addr addr;
inet_pton(AF_INET, ip.c_str(), &addr.s_addr);
return ntohl(addr.s_addr);
}
void uinttest() {
char buf[15];
for (int r1 = 0; r1 <= 255; r1++) {
for (int r2 = 0; r2 <= 255; r2++) {
for (int r3 = 0; r3 <= 255; r3++) {
for (int r4 = 0; r4 <= 255; r4++) {
snprintf(buf, sizeof(buf), "%d.%d.%d.%d", r1, r2, r3, r4);
string s(buf);
// cout << s << endl;
int ans1 = ipToNum2(s);
int ans2 = check(s);
assert(ans1 == ans2);
}
}
}
}
}
int main() {
string ip = "192.168.1.1";
auto ret = ipToNum(ip);
// 3232235777
cout << "iptonum: " << ret << endl;
struct in_addr addr;
inet_pton(AF_INET, ip.c_str(), &addr.s_addr);
cout << "inet_pton: " << addr.s_addr << endl;
uint32_t iaddr = ntohl(addr.s_addr);
cout << "ntohl: " << iaddr << endl;
uinttest();
// ipToNum2("192.168.1.1");
return 0;
}