c中的二进制到十进制

Question

我有一个简单的代码将二进制数转换为十进制数.在我的编译器中,分解对于小于1000的数字来说效果很好,超出输出总是相同的1023.任何人都有一个想法？

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

// how many power of ten is there in a number 
// (I don't use the pow() function to avoid trouble with floating numbers)
int residu(int N)
{
    int i=0;
    while(N>=1){
        N=N/10;
        i++;
    }
    return i;
}

//exponentiating a number a by a number b
int power(int a, int b){
    int i;
    int res=1;
    for (i=0;i<b;i++){res=a*res;}
    return res;
}

//converting a number N
int main()
{
    int i;

    //the number to convert
    int N;
    scanf("%d",&N);

    //the final decimal result
    int res=0;
    //we decompose N by descending powers of 10, and M is the rest
    int M=0;

    for(i=0;i<residu(N);i++){
        // simple loop to look if there is a power of (residu(N)-1-i) in N, 
        // if yes we increment the binary decomposition by 
        // power(2,residu(N)-1-i)
        if(M+ power(10,residu(N)-1-i) <= N)
        {
            M = M+power(10,residu(N)-1-i);
            res=power(2,residu(N)-1-i)+res;
        }
    }
    printf("%d\n",res);
}

Answer 1

是试试这个:

#include <stdio.h>
int main(void) 
{ 
char bin; int dec = 0;

while (bin != '\n') { 
scanf("%c",&bin); 
if (bin == '1') dec = dec * 2 + 1; 
else if (bin == '0') dec *= 2; } 

printf("%d\n", dec); 

return 0;

}