#include <stdio.h>
#include <math.h>
 
int convertDecimalToOctal(int decimalNumber);
int main()
{
    int decimalNumber;
 
    printf("输入一个十进制数: ");
    scanf("%d", &decimalNumber);
 
    printf("十进制数 %d 转换为八进制为 %d", decimalNumber, convertDecimalToOctal(decimalNumber));
 
    return 0;
}
 
int convertDecimalToOctal(int decimalNumber)
{
    int octalNumber = 0, i = 1;
 
    while (decimalNumber != 0)
    {
        octalNumber += (decimalNumber % 8) * i;
        decimalNumber /= 8;
        i *= 10;
    }
 
    return octalNumber;
}

#include <stdio.h>
#include <math.h>
 
long long convertOctalToDecimal(int octalNumber);
int main()
{
    int octalNumber;
 
    printf("输入一个八进制数: ");
    scanf("%d", &octalNumber);
 
    printf("八进制数 %d  转换为十进制为 %lld", octalNumber, convertOctalToDecimal(octalNumber));
 
    return 0;
}
 
long long convertOctalToDecimal(int octalNumber)
{
    int decimalNumber = 0, i = 0;
 
    while(octalNumber != 0)
    {
        decimalNumber += (octalNumber%10) * pow(8,i);
        ++i;
        octalNumber/=10;
    }
 
    i = 1;
 
    return decimalNumber;
}