有C语言编写一函数，输入一十六进制数，输出相应的十进制数

有C语言编写一函数，输入一十六进制数，输出相应的十进制数

#include<stdio.h>

void main(){
int i=0;
int value=0;
char ch[10];
printf("请输入一个16进制数:");
gets(ch);
while (ch[i])
{
if(ch[i]>='A'&&ch[i]<='F')
value=(ch[i]-55)+16*value;
else if(ch[i]>='a'&&ch[i]<='f')
value=(ch[i]-87)+16*value;
else if(ch[i]>='0'&&ch[i]<='9')
value=(ch[i]-48)+16*value;
else
{
printf("输入有误\n");
break;
}
i++;
}
printf("十进制数为%d\n",value);
}

#include "stdio.h" int main() { char *Str; int lenth; int i; int sum; printf("请输入你要转换的16进制数字："); gets(Str); sum=0; lenth=strlen(Str); for(i=1;i<=lenth;i++) { switch(Str[lenth-i]) { case "0":sum=sum+0*16^(lenth-i);break; case "1":sum=sum+1*16^(lenth-i);break; case "2":sum=sum+2*16^(lenth-i);break; case "3":sum=sum+3*16^(lenth-i);break; case "4":sum=sum+4*16^(lenth-i);break; case "5":sum=sum+5*16^(lenth-i);break; case "6":sum=sum+6*16^(lenth-i);break; case "7":sum=sum+7*16^(lenth-i);break; case "8":sum=sum+8*16^(lenth-i);break; case "9":sum=sum+9*16^(lenth-i);break; case "A":sum=sum+10*16^(lenth-i);break; case "B":sum=sum+11*16^(lenth-i);break; case "C":sum=sum+12*16^(lenth-i);break; case "D":sum=sum+13*16^(lenth-i);break; case "E":sum=sum+14*16^(lenth-i);break; case "F":sum=sum+15*16^(lenth-i);break; default:{printf("error\n");return(0);} } } printf("\n此16进制对应的10进制数为:%d\n",sum); }