如果没有发生缓冲区溢出，返回值始终是组合字符串的长度；这使得检测缓冲区溢出真正变得容易了。
The return value is always the size of the combined string if no buffer overflow occurred; this makes it really easy to detect an overflow.
如果参数为NULL，则openssl会将字符串写入到一个长度为256字节的静态缓冲区中，并返回指向该缓冲区的指针。
If this parameter is NULL, OpenSSL writes the string to a static buffer that is 256 bytes in length, and returns a pointer to that buffer.
如SQL标准中所述，此函数返回输入字符串的八位字节长度或字节长度。
This function, as mentioned in SQL standard, returns the length of the input string in octets or bytes.
如果参数是空序列，fn：string (seq)将返回长度为零的字符串，另一个函数则返回空白序列。
If the argument is an empty sequence, fn: string (seq) will return a zero-length string, but the other function returns an empty sequence.
如果字符串的长度为零，则返回一个未破坏的空间，否则，返回seed和竞争者的名称。
If the length of the string is zero, return a nonbreaking space; otherwise, return the seed and the name of the contestant.
函数将返回书写的字符串长度。
The fprintf() function returns the length of the written string.
这个函数将返回写入的字符串长度；如果执行失败将返回False。
This function returns the length of the written string, or FALSE on failure.
注意点：如果长度大于字符串长度，那么整个字符串将以单独的元素返回。
Note: If length is larger than the length of string, the entire string will be returned as the only element of the array.
返回改变后的字符串长度。
指定想要得到字符串的长度，(可选，没有指定则返回从指定开始位置到原字符串结束位置)。
The number of characters in the substring. If this argument is omitted, the returned substring includes all characters from the starting position to the end of the string.
返回的字符串可能与输入字符串长度不同。
The returned string might differ in length from the input string.
返回一个新字符串，该字符串通过在此字符串中的字符右侧填充空格来达到指定的总长度，从而使这些字符左对齐。
Returns a new string of a specified length in which the end of the current string is padded with Spaces or with a specified Unicode character.
返回一个新字符串，该字符串通过在此字符串中的字符右侧填充空格来达到指定的总长度，从而使这些字符左对齐。
Returns a new string of a specified length in which the end of the current string is padded with Spaces or with a specified Unicode character.
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