为什么在C 017 == 15？ [英] Why is 017 == 15 in C?

问题描述

我做的阅读字节序和用C的作用一点点，但没有真正设法澄清这一点对我来说。我刚开始学习C和我看到这个例子：

I've done a little bit of reading on endianness and its role in C, but nothing has really managed to clarify this for me. I'm just starting out with C and I saw this example:

#include <stdio.h>

int main(void) {
    int x = 017;
    int y = 12;
    int diff = x - y;
    printf("diff is %d\n", diff);
    return 0;
}

和它要求什么都会打印。我编译和运行例子，得到的差异是3，那么x是15.我的排序的看到这是为什么，不过倒很AP preciate如果有人真的澄清对我来说。

and it asks what will print. I compiled and ran the example and got that diff is 3, so x is 15. I sort of see why this is, but would really appreciate if somebody really clarified it for me.

[1]我看过类似的问题，但没有发现任何解释透的问题。如果有人可以链接我一个会也不错。

[1] I've looked for similar questions but haven't found any that explained the issue thoroughly. If someone could link me to one that would be good also.

推荐答案

prefixing与 0 若干会告诉编译器将其标记为八进制数（基数为8）

Prefixing a number with 0 will tell the compiler to mark it as a number in octal (base 8)

就像$ P $与 0X pfixing它会告诉它使用十六进制（基数为16）

Just like prefixing it with 0x will tell it to use hex (base 16)

例如：

int x = 05;  // 5 in octal
int y = 5;   // 5 in decimal
int z = 0x5; // 5 in hex

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