判断一个字符串是否base64编码

isBase64.cpp

bool isBase64(std::string s) {
	int len = s.length();
	//长度必须是4的倍数 
	if (len % 4 != 0) {
		return false;
	}
	//去掉末尾= 
	while (s[len-1] == '=') len--;
	//所有的字符必须是 0-9 a-z A-Z + / 
	for (int i = 0; i < len; i++) {
		if ((s[i] >= '0' && s[i] <= '9') || (s[i] >= 'a' && s[i] <= 'z') || (s[i] >= 'A' && s[i] <= 'Z') || s[i] == '+' || s[i] == '/') {
			continue;
		}
		return false;
	}
	return true;
}

isXXX.cpp

#define ISWS(c) ((c)==' '||(c)=='\t'||(c)=='\n')
#define ISPUNCT(c) (strchr("!\"#$%&'()*+,-./:;<=>?@[\\]^_`{|}~",(c))!=NULL)
#define ISUPPER(c) ('A' <= ((unsigned) (c)) && ((unsigned) (c)) <= 'Z')
#define ISLOWER(c) ('a' <= ((unsigned) (c)) && ((unsigned) (c)) <= 'z')
#define ISALPHA(c) (ISUPPER(c) || ISLOWER(c))
#define ISDIGIT(c) ('0' <= ((unsigned) (c)) && ((unsigned) (c)) <= '9')
#define ISXDIGIT(c) (strchr("abcdefABCDEF", c)!=NULL)
#define ISALNUM(c) (ISALPHA(c) || ISDIGIT(c))
#define ISPRINT(c) (' ' <= ((unsigned) (c)) && ((unsigned) (c)) <= 127)
#define ISVARBEG(c) (ISALPHA(c) || c == '_')
#define ISVARCHR(c) (ISALNUM(c) || c == '_')

logSwitch.cpp

#define SW_LOGINIT(sw_file) \
bool sw_can_log() { \
    static time_t last_check_time = 0; \
    static bool b_canLog = false; \
    time_t cur_time = time(nullptr); \
    if (cur_time - last_check_time > 10) { \
        if (0 == access(sw_file, F_OK)) { \
            b_canLog = true; \
        } else { \
            b_canLog = false; \
        } \
        last_check_time = cur_time; \
    } \
    return b_canLog; \
}

#define SW_LOGERR(fmt, args...) if (sw_can_log()) { LogErr(fmt, ##args); }