Convert IP address to hexadecimal number in dotted decimal form

#include   "Csapp.h"/* This code converts IP addresses in dotted decimal form to hexadecimal numbers and outputs *///returns a String representing the integer int str2int (char *str) {   //to notice the initialization of a variable   int value=0;  //string length   int length =  strlen (str);   //radix   int base=1;  while (--length!=0)  {     base*=10;  }  while (*str!= ')  {    //is calculated using ASCII code     int c = *str++;    value = value +   (c - 48)  * base;    base/=10;  }  return  value;} Converts a decimal integer to a 16-hexadecimal integer and outputs char base_10_to_base_16 (int value) {  if (value>=0&&) as a character value<=9)     return  (value+48);   else if (value>=10&& value<=15)     return  (value-10+97);} Converts an array of 16 binary integers into a string output, calling the Base_10_to_base_16 function above char* int_to_string_of_Base_16 (int value[],int bit) {  char* str =  (char *) malloc (sizeof (char) *2*bit);   char* copy_str = str;  int i;  for (i=0;i<bit;i+ +)  {    int bit_1 = value[i]/16;    int bit_2  = value[i]%16;    *str++ = base_10_to_base_16 (bit_1);     *str++ = base_10_to_base_16 (bit_2);   }  return copy_str;} Main function Void main (int argc,char* argv[]) {  if (argc<2)  {     printf ("input error!you should input like this:%s 172.20.4.163\n", argv[0]);     exit (0);   }  //Note that hex may be 4-bit or 6-bit, dynamic change   char *hex=argv [1];    //Initial number of 1  int bit_length = 1;  while (*hex!= ') )  {    if (*hex++== '. ')       bit_length++;  }  int value[bit_length];   //counter   int count = 0;  int index = 0;  char  *s = argv[1];  char *old = argv[1];  char ch;   while (*old!= ')  {    if (*old++== '. ')  {      s[count]= ' + ';       value[index++]  = str2int (s);       s=old;      count  = 0;    }    else      count+ +;    if (* (old+1) = = ' + ')       value[index++] =  Str2Int (s);    }  //output conversion result   printf ("0x%s\n", int_to_string_of_base_16 (value, bit_length));   exit (0);}

Convert IP address to hexadecimal number in dotted decimal form