C Language String

C Language String

First, the string basis

Note: The string must end with a.

Printf ("yang\n");

Where Yang is a string constant, "yang" = ' y ' + ' a ' + ' n ' + ' g ' + '. Strings consist of a number of characters, usually using a character array to store strings, such as Char name[10]= "Yang", or in the form of printf (name), which is the way to access strings through an array, but there is a warning. Because by default, the printf function accepts only string constants as arguments (not the variables).

Three ways to type a string:

1. Char name[8]= "Yang";//Arrays occupy 8 bytes of storage space, but contain only 5 characters.
2. Char name[8]={' y ' + ' a ' + ' n ' + ' g ' + ' \o '};
3. Char name[8]={' y ' + ' a ' + ' n ' + ' G ' + ' 0 '};

These three types of writing are the same in memory.

Char name[]={' y ' + ' a '}; The preceding number is not written, it is not a string, it can only be said to be an ordinary character array.

Char name[]= "Yang";

name[1]= ' o '; change the value of the second element of the string from a to O.

Second, the use of the string note points

(1) Analyze the code to understand the role of the.

Char name[]= "Yang";

Char name2[]={' o ' + ' k '};

Printf ("name2=%s", name2);

%s: Print the string according to the parameters on the right (until you have encountered a)

The above code prints the result: Okyang

The following is an analysis of memory conditions:

Ask 1:char name[]= "y\0ng"; print the result why? (Oky)

Q 2: Print the value of name at this time, what is the use of%s? Y\0ng or Y?

(2) Strlen function

The Strlen function calculates the length of a string (the number of characters) but does not include the number of characters. For example, a Chinese character occupies three characters.

Strlen ("haha");//Length of 4

Strlen ("ha haha");//Length 7 instead of 5

Set

Char name[]= "It\0cast";

Strlen (name); The value is 2 because Strlen is calculated from the address of the string until it encounters a.

Assume

Char name[]= "Itcast";

Char name2[]={' o ' + ' k '};

Int Size=strlen (name);

The value of size at this time is 8.

(3) Practice, write a function char_contains (char Str[],char c), if the string contains the character C, then return 1, otherwise return 0.

Int Char_contains (char Str[],char c)

{

Traverse the entire string

for (int i=0,i<strlen (str); i++)

{

If (STR[I]==C)

Return 1;

}

Return 0;

}

Invoke statement

Int result=char_contains ("Yang", ' a ');

Using the While loop

①. while (I<strlen (str))

②. while (str[i]!= ')

③. while (Str[i])

④. Int i=-1;while (str[i++])

Three, a string array

A two-dimensional character array that stores two string arrays, each with a length of 1, and the following two types of notation, but the storage is the same.

Char name[2][10]={"Jack", "Rose"};

Char name2[2][10]={

{' J ' + ' a ' + ' C ' + ' K ' + ' + '},

{' R ' + ' O ' + ' s ' + ' e ' + ' + '}

}

Output Rose: printf ("%s", name2[1]);

Output k:printf ("%c", name2[0][3]);

C Language String