十六进制转成十进制.c

16 specific algorithm for converting binary to decimal is:
(1) First of all, understand that 16 number ( from right to left the No. 0, 1th, 2nd – ) weights for No. 0 - 0 16, 1th - 1 of the weight of 16, the 2nd - 2 of the weight is 16, and then click Arrange it.
(2) See binary number represented by the ABCDEF is 10,11,12,13,14,15.
(3) 16 is the formula for converting binary to decimal : from right to left, with each binary number multiplied by 16 of the appropriate party, and then just numbers.

//  date:2020/3/4
//  author:xiezhg5
#include <stdio.h>
#define MAX 1000                        //宏定义 
int main(void)
{
	int change(char s[]);               //定义change函数用于进制转换 
	int c,i,flag,flag1;
	char t[MAX]; 
	i=0;                                //控制变量i 
	flag=0;                             //目标变量flag 
	flag1=1;                            //flag判断变量 
	printf("请输入一个十六进制数:\n");
	while((c=getchar())!='\0'&&i<MAX&&flag1)  //getchar()函数  
	{
		if(c>='0'&&c<='9'||c>='a'&&c<='f'||c>='A'&&c<='F')
		{
			flag=1;
			t[i++]=c;   //将c的值储存在数组t[i++]中符合人们习惯(不是t[i]) 
		}
		else if(flag)
		{
			t[i]='\0';
			printf("十进制数:%d\n",change(t));    //调用change函数
			printf("继续或终止?\n"); 
			c=getchar();
			//if--else嵌套 cx
			if(c=='N'||c=='n')                   //(终止情况) 
			flag1=0;
			else                                 //(继续情况)
			{
				flag=0;
				i=0;
				printf("请输入一个十六进制数:\n");
			}
		}
	}
}

int change(char s[])
{
	int i,n;
	n=0;
	for(i=0;s[i]!='\0';i++)
	{
		//十六进制转十进制核心算法 
		if(s[i]>='0'&&s[i]<='9')
		n=n*16+s[i]-'0';
		if(s[i]>='a'&&s[i]<='f')
		n=n*16+s[i]-'a'+10;
		if(s[i]>='A'&&s[i]<='F')
		n=n*16+s[i]-'A'+10;
	}
	
	return(n);
}