C - 将二进制转换为十进制的算法 - 不起作用

Question

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

int main()
{
char c1,c2,c3,c4,c5;
int x;

scanf(" %c %c %c %c %c",&c1,&c2,&c3,&c4,&c5);

if (c1,c2,c3,c4,c5 !='0' && c1,c2,c3,c4,c5 !='1'){
    printf("Not a binary number!");

    }

if (c1=='0' && c2,c3,c4,c5=='0' || c2,c3,c4,c5 =='1'){

    c5 = c5-48;
    c4 = (c4-48)*2;
    c3 = (c3-48)*4;
    c2 = (c2-48)*8;
    c1 = c1-48;

    x = c5+c4+c3+c2+c1;
    printf("%d",x);
    }

return 0;
}

因此，该代码适用于所有数字，除了最后一个 (c5) 字符输入 0(零)时。当发生这种情况时，我得到“不是二进制数!”。我的错误在哪里？ :)

我才刚开始接触 C 和编程，所以请善待我，呵呵

Answer 1

首先你不能一次取二进制数字，你有c1到c5，如果用户输入二进制为100怎么办，就不行了。所以尝试这样的事情。试试这个:

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

int main()
{

int val, base = 1,cn, decinum = 0,rest;
int alert = 0;
printf("Please enter a binary number 0's and 1's: ");

scanf("%d",&val);

cn = val;   // saving it for printf
while(val > 0){
    rest = val % 10;

    if(rest == 0 || rest == 1) {
        decinum += rest * base;
        val /= 10;
        base *= 2;

    }else{
        alert = 1;
        break;
    }
}


if(alert){
    printf("Sorry not a binary number\n");
}else{
    printf("binary: %d ist %d",cn,decinum);
}


return 0;
}

Please enter a binary number 0's and 1's: 01120100

output: Sorry not a binary number

Please enter a binary number 0's and 1's: 101

Output: binary: 101 ist 5

从 cpatricio 和 Jonathan 的评论中，您想到的二进制数很大，例如 8 位，最多 20 位

int main()
{

unsigned long  val,cn, decinum = 0;
int rest, base = 1;
int alert = 0;
printf("Please enter a binary number 0's and 1's: ");

scanf("%lu",&val);

cn = val;  // save it for printf otherwise after the while loop is val = 0

while(val > 0){
    rest = val % 10;

    if(rest == 0 || rest == 1) {
        decinum += rest * base;
        val /= 10;
        base *= 2;

    }else{
        alert = 1;
        break;
    }
}


if(alert){
    printf("Sorry not a binary number\n");
}else{
    printf("binary: %lu ist %ld",cn,decinum);
}


return 0;
}

probe Output: Please enter a binary number 0's and 1's:010101100001001011000 binary: 010101100001001011000 ist 705112

Output: Please enter a binary number 0's and 1's:0000001001011000 binary: 0000001001011000 ist 600