来自马的口

None of BCPL, B, or C supports character data strongly in the language; each treats strings much like vectors of integers and supplements general rules by a few conventions. In both BCPL and B a string literal denotes the address of a static area initialized with the characters of the string, packed into cells. In BCPL, the first packed byte contains the number of characters in the string; in B, there is no count and strings are terminated by a special character, which B spelled *e. This change was made partially to avoid the limitation on the length of a string caused by holding the count in an 8- or 9-bit slot, and partly because maintaining the count seemed, in our experience, less convenient than using a terminator.

Dennis M Ritchie, C语言的开发

C语言中没有字符串。C语言中的“string”只是一个指向char的指针。所以也许你问错问题了。

“省略字符串类型的基本原理是什么”可能更相关。对此，我要指出C不是面向对象的语言，只有基本的值类型。字符串是一个更高级别的概念，必须以某种方式组合其他类型的值来实现。C处于较低的抽象级别。

鉴于下面的狂风暴雨

我只是想指出，我并不是想说这是一个愚蠢或糟糕的问题，或者C语言表示字符串的方式是最好的选择。我试图澄清的是，如果考虑到C语言没有区分字符串作为数据类型与字节数组的机制这一事实，那么这个问题就会更简洁。考虑到今天计算机的处理和存储能力，这是最好的选择吗?可能不会。但事后诸葛总是20/20之类的。

懒惰、寄存器节俭和可移植性考虑到任何语言的汇编核心，尤其是C语言，它比汇编高出一步(因此继承了大量汇编遗留代码)。 你会同意null字符在那些ASCII的日子里是无用的，它(可能和EOF控件字符一样好)。

让我们看看伪代码

function readString(string) // 1 parameter: 1 register or 1 stact entries
    pointer=addressOf(string) 
    while(string[pointer]!=CONTROL_CHAR) do
        read(string[pointer])
        increment pointer

共使用1个寄存器

案例2

 function readString(length,string) // 2 parameters: 2 register used or 2 stack entries
     pointer=addressOf(string) 
     while(length>0) do 
         read(string[pointer])
         increment pointer
         decrement length

共使用2个寄存器

这在当时似乎是短视的，但考虑到代码和寄存器的节俭(这在当时是PREMIUM，那时你知道，他们使用穿孔卡)。因此，更快(当处理器速度可以以kHz计)，这个“黑客”是相当不错的，可轻松移植到无寄存器处理器。

为了便于讨论，我将实现2个常见的字符串操作

stringLength(string)
     pointer=addressOf(string)
     while(string[pointer]!=CONTROL_CHAR) do
         increment pointer
     return pointer-addressOf(string)

复杂度O(n)，在大多数情况下PASCAL字符串是O(1)，因为字符串的长度是预先挂起的字符串结构(这也意味着该操作必须在更早的阶段进行)。

concatString(string1,string2)
     length1=stringLength(string1)
     length2=stringLength(string2)
     string3=allocate(string1+string2)
     pointer1=addressOf(string1)
     pointer3=addressOf(string3)
     while(string1[pointer1]!=CONTROL_CHAR) do
         string3[pointer3]=string1[pointer1]
         increment pointer3
         increment pointer1
     pointer2=addressOf(string2)
     while(string2[pointer2]!=CONTROL_CHAR) do
         string3[pointer3]=string2[pointer2]
         increment pointer3
         increment pointer1
     return string3

复杂度O(n)和预先设置字符串长度不会改变操作的复杂性，而我承认它会减少3倍的时间。

另一方面,如果你使用PASCAL字符串将不得不重新设计您的API来考虑在长度和bit-endianness注册,帕斯卡字符串的众所周知的限制255字符(0 xff)因为中存储的长度是1个字节(8位),而且你想要更长的字符串(16位- >任何)你必须考虑在一层的架构代码,这意味着在大多数情况下不相容的字符串API如果你想要更长的字符串。

例子:

One file was written with your prepended string api on an 8 bit computer and then would have to be read on say a 32 bit computer, what would the lazy program do considers that your 4bytes are the length of the string then allocate that lot of memory then attempt to read that many bytes. Another case would be PPC 32 byte string read(little endian) onto a x86 (big endian), of course if you don't know that one is written by the other there would be trouble. 1 byte length (0x00000001) would become 16777216 (0x0100000) that is 16 MB for reading a 1 byte string. Of course you would say that people should agree on one standard but even 16bit unicode got little and big endianness.

当然，C也有它的问题，但它不会受到这里提出的问题的影响。

在很多方面，C语言是原始的。我很喜欢。

它比汇编语言高了一步，用一种更容易编写和维护的语言提供了几乎相同的性能。

空结束符很简单，不需要语言的特殊支持。

现在回想起来，似乎并不是那么方便。但我在80年代使用汇编语言，当时它似乎非常方便。我只是认为软件在不断地发展，平台和工具也在不断地变得越来越复杂。

我认为，这是有历史原因的，我在维基百科上找到了这个:

At the time C (and the languages that it was derived from) were developed, memory was extremely limited, so using only one byte of overhead to store the length of a string was attractive. The only popular alternative at that time, usually called a "Pascal string" (though also used by early versions of BASIC), used a leading byte to store the length of the string. This allows the string to contain NUL and made finding the length need only one memory access (O(1) (constant) time). But one byte limits the length to 255. This length limitation was far more restrictive than the problems with the C string, so the C string in general won out.

GCC接受以下代码:

Char s[4] = "abcd";

如果我们把is当作字符数组，而不是字符串数组，这是可以的。也就是说，我们可以使用s[0]， s[1]， s[2]和s[3]，甚至使用memcpy(dest, s, 4)访问它。但是当我们尝试使用put (s)时，我们会得到混乱的字符，或者更糟糕的是使用strcpy(dest, s)。