用C++写一个十六进制转八进制

#include <stdio.h>
#include <string.h>

int main() {
    char hex[100];
    int len, i, j, oct[100], k = 0;
    printf("请输入一个十六进制数：");
    scanf("%s", hex);
    len = strlen(hex);
    for (i = len - 1; i >= 0; i--) {
        switch (hex[i]) {
            case '0':
                oct[k++] = 0;
                oct[k++] = 0;
                oct[k++] = 0;
                oct[k++] = 0;
                break;
            case '1':
                oct[k++] = 1;
                oct[k++] = 0;
                oct[k++] = 0;
                oct[k++] = 0;
                break;
            case '2':
                oct[k++] = 0;
                oct[k++] = 1;
                oct[k++] = 0;
                oct[k++] = 0;
                break;
            case '3':
                oct[k++] = 1;
                oct[k++] = 1;
                oct[k++] = 0;
                oct[k++] = 0;
                break;
            case '4':
                oct[k++] = 0;
                oct[k++] = 0;
                oct[k++] = 1;
                oct[k++] = 0;
                break;
            case '5':
                oct[k++] = 1;
                oct[k++] = 0;
                oct[k++] = 1;
                oct[k++] = 0;
                break;
            case '6':
                oct[k++] = 0;
                oct[k++] = 1;
                oct[k++] = 1;
                oct[k++] = 0;
                break;
            case '7':
                oct[k++] = 1;
                oct[k++] = 1;
                oct[k++] = 1;
                oct[k++] = 0;
                break;
            case '8':
                oct[k++] = 0;
                oct[k++] = 0;
                oct[k++] = 0;
                oct[k++] = 1;
                break;
            case '9':
                oct[k++] = 1;
                oct[k++] = 0;
                oct[k++] = 0;
                oct[k++] = 1;
                break;
            case 'A':
            case 'a':
                oct[k++] = 0;
                oct[k++] = 1;
                oct[k++] = 0;
                oct[k++] = 1;
                break;
            case 'B':
            case 'b':
                oct[k++] = 1;
                oct[k++] = 1;
                oct[k++] = 0;
                oct[k++] = 1;
                break;
            case 'C':
            case 'c':
                oct[k++] = 0;
                oct[k++] = 0;
                oct[k++] = 1;
                oct[k++] = 1;
                break;
            case 'D':
            case 'd':
                oct[k++] = 1;
                oct[k++] = 0;
                oct[k++] = 1;
                oct[k++] = 1;
                break;
            case 'E':
            case 'e':
                oct[k++] = 0;
                oct[k++] = 1;
                oct[k++] = 1;
                oct[k++] = 1;
                break;
            case 'F':
            case 'f':
                oct[k++] = 1;
                oct[k++] = 1;
                oct[k++] = 1;
                oct[k++] = 1;
                break;
            default:
                printf("输入的十六进制数有误！\n");
                return 0;
        }
    }
    printf("转换为八进制数为：");
    if (k % 3 == 1) {
        printf("%d", oct[0]);
        for (i = 1; i < k; i += 3) {
            printf("%d", oct[i] * 4 + oct[i + 1] * 2 + oct[i + 2]);
        }
    } else if (k % 3 == 2) {
        printf("%d", oct[0] * 2 + oct[1]);
        for (i = 2; i < k; i += 3) {
            printf("%d", oct[i] * 4 + oct[i + 1] * 2 + oct[i + 2]);
        }
    } else {
        for (i = 0; i < k; i += 3) {
            printf("%d", oct[i] * 4 + oct[i + 1] * 2 + oct[i + 2]);
        }
    }
    printf("\n");
    return 0;
}