十六进制和二进制的转换
#include <stdio.h>
#include <math.h>
#include <string.h>
char* strrev(char* s)
void binary_hex(int n, char hex[]);
int hex_binary(char hex[]);
char* strrev(char* s)
{
/* h指向s的头部 */
char* h = s;
char* t = s;
char ch;
/* t指向s的尾部 */
while(*t++){};
t--; /* 与t++抵消 */
t--; /* 回跳过结束符'\0' */
/* 当h和t未重合时，交换它们所指向的字符 */
while(h < t)
{
ch = *h;
*h++ = *t; /* h向尾部移动 */
*t-- = ch; /* t向头部移动 */
}
return(s);
}
int main()
{
char hex[20],c;
int n;
printf("Instructions:\n");
printf("Enter h to convert binary to hexadecimal:\n");
printf("Enter b to hexadecimal number to binary:\n");
printf("Enter a character: ");
scanf("%c",&c);
if (c=='h' || c=='H')
{
printf("Enter binary number: ");
scanf("%d",&n);
binary_hex(n,hex);
printf("Hexadecimal number: %s",hex);
}
if (c=='b' || c=='B')
{
printf("Enter hexadecimal number: ");
scanf("%s",hex);
printf("Binary number: %d",hex_binary(hex));
}
return 0;
}
void binary_hex(int n, char hex[]) /* Function to convert binary to h. */
{
int i=0,decimal=0, rem;
while (n!=0)
{
decimal += (n%10)*pow(2,i);
n/=10;
++i;
}
/* At this point, variable decimal contains binary number in decimal format. */
i=0;
while (decimal!=0)
{
rem=decimal%16;
switch(rem)
{
case 10:
hex[i]='A';
break;
case 11:
hex[i]='B';
break;
case 12:
hex[i]='C';
break;
case 13:
hex[i]='D';
break;
case 14:
hex[i]='E';
break;
case 15:
hex[i]='F';
break;
default:
hex[i]=rem+'0';
break;
}
++i;
decimal/=16;
}
hex[i]='\0';
strrev(hex); /* Function to reverse string. */
}
int hex_binary(char hex[]) /* Function to convert hexadecimal to binary. */
{
int i, length, decimal=0, binary=0;
for(length=0; hex[length]!='\0'; ++length);
for(i=0; hex[i]!='\0'; ++i, --length)
{
if(hex[i]>='0' && hex[i]<='9')
decimal+=(hex[i]-'0')*pow(16,length-1);
if(hex[i]>='A' && hex[i]<='F')
decimal+=(hex[i]-55)*pow(16,length-1);
if(hex[i]>='a' && hex[i]<='f')
decimal+=(hex[i]-87)*pow(16,length-1);
}
/* At this point, variable decimal contains the hexadecimal number in decimal format. */
i=1;
while (decimal!=0)
{
binary+=(decimal%2)*i;
decimal/=2;
i*=10;
}
return binary;
}