C language learning log 12.14

One . Escape character

Used to express control characters or special characters that cannot be printed , It's made up of a backslash “\“ start , Followed by another character , These two characters combine , Make up a character .

  Two . character string

It is a 0（ Integers 0） A string of characters at the end ,0 or ”\0" It's the same , But and '0' Different

0 Marks the end of the string , But it's not part of a string , This is not included when calculating the length of the string 0

String exists as an array , Access as an array or pointer , More in the form of pointers

string.h There are many functions to handle strings in .

Tips: C Language strings exist in the form of character arrays

          You cannot operate on a string with an operator

          You can traverse the string through the array

String variable ：                                                                String constant ：

The string can be stored in the following form ：                                    for example ：char* s ="Hello,world!";

char * Variable name = "Hello";                                                  s It's a pointer , Initializes to point to a string char Variable name [] = "Hello";                                                  The amount , Because of where this constant is , actually s yes char Variable name [10] = "Hello";                                             const char* s, But for historical reasons , compile                                                                                            Device not accepted const Writing . But try to s Referred to                                                                                         Writing strings can lead to serious consequences .

If you need to modify the string , You should use arrays ：

char s[] = "Hello,world!";

So use a pointer or an array ？

Array ： This string is here

         The space is automatically reclaimed as a local variable

The pointer ： I don't know where this string is

        Processing parameters

        Dynamically allocate space