# C 程序：将二进制转换为八进制数 > 原文： [https://beginnersbook.com/2017/09/c-program-to-convert-binary-to-octal-number-system/](https://beginnersbook.com/2017/09/c-program-to-convert-binary-to-octal-number-system/) 该 C 程序将二进制数转换为等效的八进制数。 ## 示例：将二进制转换为八进制的程序 在该程序中，要求用户输入二进制数，然后程序通过调用用户定义的函数将该二进制数转换为八进制数。要理解这个程序，您应该熟悉以下 [C 编程](https://beginnersbook.com/2014/01/c-tutorial-for-beginners-with-examples/)概念： 1. [C - `while`循环](https://beginnersbook.com/2014/01/c-while-loop/) 2. [C - 函数](https://beginnersbook.com/2014/01/c-functions-examples/) ```c #include <stdio.h> #include <math.h> //This function converts binary number to octal number int binaryToOctal(long binarynum) { int octalnum = 0, decimalnum = 0, i = 0; /* This while loop converts binary number "binarynum" to the * decimal number "decimalnum" */ while(binarynum != 0) { decimalnum = decimalnum + (binarynum%10) * pow(2,i); i++; binarynum = binarynum / 10; } //i is re-initialized i = 1; /* This loop converts the decimal number "decimalnum" to the octal * number "octalnum" */ while (decimalnum != 0) { octalnum = octalnum + (decimalnum % 8) * i; decimalnum = decimalnum / 8; i = i * 10; } //Returning the octal number that we got from binary number return octalnum; } int main() { long binarynum; printf("Enter a binary number: "); scanf("%ld", &binarynum); // calling the function here printf("Equivalent octal value: %d", binaryToOctal(binarynum)); return 0; } ``` **输出：** ```c Enter a binary number: 111001 Equivalent octal value: 71 ``` 在这个程序中，我们首先将输入的二进制数转换为十进制数，然后我们将该十进制数转换为八进制数。 看看这些相关的 C 程序： 1. [C 程序：将二进制转换为十进制](https://beginnersbook.com/2015/02/c-program-to-convert-binary-number-to-decimal-number/) 2. [C 程序：将十进制数转换为二进制数](https://beginnersbook.com/2017/09/c-program-to-convert-decimal-number-to-binary-number/) 3. [C 程序：将八进制数转换为二进制数](https://beginnersbook.com/2017/09/c-program-to-convert-octal-number-to-binary-number/) 4. [C 程序：将小写字符串转换为大写](https://beginnersbook.com/2015/02/c-program-to-convert-lowercase-string-to-uppercase-string/) 5. [C 程序：将大写字符串转换为小写](https://beginnersbook.com/2015/02/c-program-to-convert-uppercase-string-to-lowercase-string/)