您如何验证字符串是C中的有效MAC地址?

问题描述

示例:

12:45:ff:ab:aa:cd    is valid
45:jj:jj:kk:ui>cd    is not valid

推荐答案

以下代码检查有效的MAC地址(带或不带:"分隔符):

The following code checks for valid MAC addresses (with or w/o the ":" separator):

#include <ctype.h>

int isValidMacAddress(const char* mac) {
    int i = 0;
    int s = 0;

    while (*mac) {
       if (isxdigit(*mac)) {
          i++;
       }
       else if (*mac == ':' || *mac == '-') {

          if (i == 0 || i / 2 - 1 != s)
            break;

          ++s;
       }
       else {
           s = -1;
       }


       ++mac;
    }

    return (i == 12 && (s == 5 || s == 0));
}

代码检查以下内容:

• 输入字符串mac恰好包含12个十六进制数字.
• 如果输入字符串中出现分隔冒号:，则仅在偶数个十六进制数字之后出现.

• that the input string mac contains exactly 12 hexadecimal digits.
• that, if a separator colon : appears in the input string, it only appears after an even number of hex digits.

它是这样的:

• i，它是mac中的十六进制数字，被初始化为0.
• while循环输入字符串中的每个字符，直到字符串结尾或检测到12个十六进制数字.
  • 如果当前字符(*mac)是有效的十六进制数字，则i递增，然后循环检查下一个字符.
  • 否则，循环将检查当前字符是否为分隔符(冒号或破折号)；如果是这样，它将验证每对十六进制数字是否有一个分隔符.否则，循环将中止.
  • i,which is the number of hex digits in mac, is initialized to 0.
  • The while loops over every character in the input string until either the string ends, or 12 hex digits have been detected.
    • If the current character (*mac) is a valid hex digit, then i is incremented, and the loop examines the next character.
    • Otherwise, the loop checks if the current character is a separator (colon or a dash); if so, it verifies that there is one separator for every pair of hex digits. Otherwise, the loop is aborted.

    如果您不想接受分隔符，只需将return语句更改为:

    If you don't want to accept separators, simply change the return statement to:

    return (i == 12 && s == 0);
    

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