11- character array and string functions

An array of int float double

char array of characters

First, the array of characters

1 , generally in the form of an array of characters

char array name [ constant expression ]

char cArray[5];

2 , reference character array is the same as with other types, with the subscript.

char cArray[5];

cArray[0]='H';

CArray [1] = 'and';

cArray[2]='l';

cArray[3]='l';

CArray [4] = 'a';

3 , initialize the array of characters

(1) to initialize the elements one by one can be omitted index initialization.

CArray char [5] = {H ',' e ',' l ',' l ',' o '};

CArray char [] = {H ',' e ',' l ',' l ',' o '};

(2) a string for array assignment, initialization can be omitted subscripts

char cArray[5] = {"hello"};

char cArray[]={"hello"};

char cArray [] = "hello" ; ( most common )

Note: 1 , the use of strings is initialized, the system will automatically add an array inside a '\ 0' , as the end of the string flag

char cArray [] = "hello" ; equivalent to char cArray [] = { 'H ', 'e', 'l', 'l', 'o', '\ 0'};

printf("%d\n", sizeof(cArray));

printf("%d\n", sizeof(cArray1));

Note: 2 , a string of bytes Chinese Chinese is 2.

printf("%d", sizeof("九夏"));// \0

3, the initialization string, array sizes large number of elements than we need.

For example, the length of the name is not the same

4 , the input and output array of characters

( 1 ) a % c input by one output

Enter the number of characters greater than the number of array size, only accept the front.

 1 #include <stdio.h>
 2 
 3 int main()
 4 {
 5     char cArray[5];
 6     for (int i = 0; i < 5; i++)
 7     {
 8         scanf("%c", &cArray[i]);
 9     }
10 
11     for (int i = 0; i < 10; i++)
12     {
13         printf("%c", cArray[i]);
14     }
15 
16     printf("\n");
17     return 0;
18 }

( 2 ) with a % s overall input and output, the input space is truncated

 1 #include <stdio.h>
 2 
 3 int main()
 4 {
 5     char cArray[20];
 6     scanf("%s", &cArray);
 7 
 8     printf("%s", cArray);
 9     return 0;
10 }

 1 #include <stdio.h>
 2 
 3 int main()
 4 { 
 5     //%c
 6 
 7     /*int Row, Col;
 8     char cArray[2][5]; 
 9 
10     for (Row = 0; Row < 2; Row++)
11     {
12         for (Col = 0; Col < 5;Col++)
13         {
14             scanf("%c", &cArray[Row][Col]);
15         }
16     } 
17 
18     for (Row = 0; Row < 2; Row++)
19     {
20         for (Col = 0; Col < 5; Col++)
21         {
22             printf("%c", cArray[Row][Col]);
23         }
24     }*/
25 
26      
27     //%s
28     int Row, Col;
29     char cArray[11];     
30     scanf("%s", &cArray);
31     printf("%s", cArray);
32 
33     return 0;
34 }

Second, String Functions

First you need to include the header file strings: string.h

1 copy

strcpy ( target string, the source string );

Copy the source string into the target string.

( 1 ) the target must be a string variable.

( 2 ) the source string is not necessarily.

( 3 ) Even '\ 0' copy together , the first '\ 0' end

1  Code:
 2  // copy string Assume a string of character array str1 [] str2 []
 . 3  
. 4  // char str1 [30] = {0}; // 0 27 months \ 0 \ 0 \ 0
 . 5  / / char str2 [30] = "hellosadfsadfgoisdfgsdkfg";   // . 6 characters
 . 6  
. 7  // the printf ( "% D", the sizeof (str2));
 . 8  
. 9   
10  // for (int I = 0; I <the sizeof (str2 ); I ++)
 . 11  // {
 12 is      // str1 [I] = str2 [I];
 13 is  // }
 14  
15  // the printf ( "% S \ n-", str1);
 16  
. 17   
18 is  
. 19 // char str1 [] = "ABCDEFG";   // index memory for the decision variables   //   \ 0 End
 20 is  @ 
21 is  
22 is  // strcpy (str1, "FGH");   // \ 0
 23 is  
24  // the printf ( "C% \ n-", str1 [0]);
 25  // the printf ( "% C \ n-", str1 [. 1]);
 26 is  // the printf ( "% C \ n-", str1 [2]);
 27  // the printf ( "% C \ n-", str1 [. 3]);
 28  // the printf ( "% C \ n-", str1 [. 4]);
 29  // the printf ( "% C \ n-", str1 [ . 5]);
 30  // the printf ( "% C \ n-", str1 [. 6]);
31 
32  
33 //printf("%s\n", str1);

2 , more

strcmp ( string 1 and string 2);

( 1 ) String 1 == string 2 returns 0

( 2 ) string 1> string 2 return 1

( 3 ) string 1 < string 2 returns -1

 1 //字符串的比较
 2 //char str1[100], str2[100];
 3 
 4 //while (1)
 5 //{
 6     // int i = 0, re;
 7     // scanf("%s", &str1);
 8     // scanf("%s", &str2);
 9 
10     // while (str1[i])
11     // {
12         // if (str1[i] != str2[i])  //str1[0]----->str1[99]  
13             // break;
14         // else
15             // i++;
16     // }
17 
18     // if (str1[i] > str2[i])
19     // {
20         // printf("str1>str2\n");
21     // }
22     // else if (str1[i] < str2[i])
23     // {
24         // printf("str1<str2\n");
25     // }
26     // else
27     // {
28         // printf("str1=str2\n");
29     // }
30 //}
31 
32  
33 
34 /*int num = 1;
35 
36 char str1 [30] = "Hello";
 37 [  char str2 [30];
 38 is  
39  the printf ( "To enter the system Enter password: \ n-");
 40  the while (. 1)
 41 is  {
 42 is      Scanf ( "% S", & str2 );
 43 is      IF (strcmp (str1, str2) == 0)
 44 is      {
 45          the printf ( "Welcome to the system, although the system is still in development ...");
 46 is      }
 47      the else IF (strcmp (str1, str2 !) = 0)
 48      {
 49          NUM ++;
 50          the printf ( "wrong password, this is the% d warnings \ n-", NUM);
 51 is          IF (NUM ==. 4)
 52 is          {
 53 is              the printf ( ". 3 times error, Contact People's Liberation Army \ n ");
54             break;
55         }
56 
57         continue;
58     }
59 
60 }

3, Get string length

// sizeof (); // byte

// strlen (); // true ( effective ) length

char a[30] = "hello";

printf("%d\n", sizeof(a));//30

printf("%d\n", strlen(a)); //5

11- character array and string functions

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