点分10进制ipv4地址与整数的转换

整数型的ipv4地址为无符号32位整数，注意这点即可

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

void str2int(char *str, unsigned int *ip)
{
    int cnt = 0;
    char num_buf[5] = {0};
    int buf_cnt = 0;
    unsigned int ip_value = 0;
    int bit = 3;

    while(1){
        if(str[cnt] >= '0' && str[cnt] <= '9' && str[cnt] != '\0'){
            num_buf[buf_cnt++] = str[cnt];
        }
        else{
            ip_value += strtol(num_buf,NULL,0)*(1<<(bit*8));
            memset(num_buf,0,5);
            buf_cnt = 0;
            bit--;
        }
        if(str[cnt] == '\0'){
            break;
        }
        else{
            cnt++;
        }
    }

    *ip = ip_value;
}

void int2str(unsigned int ip, char *str)
{
    char part[10] = {0};

    for(int i = 0; i < 4;i++){
        sprintf(part,"%d.",ip / (1<<((3-i)*8)));
        strcat(str,part);
        memset(part,0,10);
        ip = ip%(1<<((3-i)*8));
    }
    str[strlen(str)-1] = '\0';
}

int main(void)
{
    unsigned int ip_addr;
    char buf[20] = {0};
    char ip_str[20] = {0};
    unsigned int tmp;
   // strcpy(ip_str,"10.0.3.193");
    //ip_addr = 167969729;
    while((scanf("%s",ip_str)) != EOF){
        scanf("%d",&ip_addr);
        str2int(ip_str, &tmp);
        printf("%u\n",tmp);
        int2str(ip_addr,buf);
        printf("%s\n",buf);
        memset(buf,0,20);
        memset(ip_str,0,20);
    }

    return 0;
}