C-language arrays (one-dimensional, character)

Main.m

1-16 class Notes

Lecturer: Xiao Hui

Author: Wang Xuewen

Created by Lanouhn on 15/1/16.

Copyright (c) 2015 Lanouhn. All rights reserved.

Array (one-dimensional, character)

#import <Foundation/Foundation.h>

int main (int argc, const char * argv[]) {

Arrays: Ordered queues for storing the same data types

Format of the array definition

Data type variable name [number of elements] = {value 1, value 2, Value 3, ...}

Array of integral type

int array[5] = {1, 2, 3, 4, 5};

//

Floating-point arrays

Float Array1[5] = {1.0, 2.0, 3.0, 4.0, 5.0};

//

Array out of bounds, very dangerous

int a[2] = {1, 2, 3};

//

How arrays are defined

int b[4] = {1, 2, 3};//1, 2, 3, 0

//

int c[4] = {1};//1, 0, 0, 0

//

int d[4] = {0};//is all 0

//

The number of array elements is omitted, but the initial value must be assigned, otherwise there is no way to determine the number of elements

int e[] = {1, 2, 3, 4};//has four elements

//

int g[] = {0};//has an element

//

int h[] = {};//0 elements, meaningless

//

sizeof (); Calculate the number of bytes that the data type or variable occupies

/*

Calculate the number of bytes in a data type

unsigned long length = sizeof (short);

printf ("short:%lu\n", length);

Calculate the number of bytes in a variable

int i = 0;

printf ("int:%lu\n", sizeof (i));

printf ("short:%lu\n", sizeof (short));//value range: -2^15 to 2^15-1

printf ("int:%lu\n", sizeof (int));//value range: -2^31 to 2^31-1

printf ("char:%lu\n", sizeof (char)); Range of values: -2^7 to 2^7-1

printf ("long:%lu\n", sizeof (long));//value range: -2^63 to 2^63-1

printf ("float:%lu\n", sizeof (float));//value range: -2^31 to 2^31-1

printf ("double:%lu\n", sizeof (double));//value range: -2^63 to 2^63-1

Number of bytes in the array = number of bytes in the data type + number of array elements

int a[5] = {1, 2, 3, 4, 5};

printf ("%lu\n", sizeof (a));

Use of arrays

int k = 2, j = 3;

K + J;

Arrays cannot participate directly in operations, and elements in an array can participate in operations

int arr1[2] = {1, 2};

int arr2[2] = {4, 5};

ARR1 + arr2

Gets the elements in the array

Format: array name [element subscript]

(*) element subscript starts from zero

The range of the original acid subscript {0, number of array elements-1}

int a[5] = {1, 2, 3, 4, 5};

printf ("%d\n", a[0]);//The first element of an array

Array out of bounds

A[5]

Define the difference between an array and an array element

1. Defining an array must have a data type

2. When defining an array, the number of elements can be omitted; When you take an array element, the subscript of the element cannot be omitted.

Iterate through each element in the array and print

for (int i = 0; I <= 4; i++) {

printf ("a[%d] =%d\n", I, a[i]);

}

Assign a value to an array of elements

A[2] = 6;

Defines an integer array with 20 elements, with each element having a value range of 30-70

int a[20] = {0};

int sum = 0;

for (int i = 0; i <; i++) {

int temp = arc4random ()% 41 + 30;

int n = 0;

if (n < 20) {

A[n] = temp;

n++;

//}

A[i] = temp;

Sum =sum + temp;

printf ("a[%d] =%d\n", I, a[i]);

}

printf ("sum =%d\n", sum);

Copy an array, which is two array capacity, to copy the elements of one of the arrays into another array

int b[20] = {0};

for (int i = 0; i <; i++) {

B[i] = A[i];

printf ("b[%d] =%d\n", I, b[i]);

}

Generates 2 arrays, each with 10 elements, an element with a value range of 20-40, an array of corresponding elements added, and placed in another array

int a[10] ={0};

int b[10] = {0};

int c[10] = {0};

for (int i = 0; i < i++) {

A[i] = arc4random ()% 21 + 20;

B[i] = arc4random ()% 21 + 20;

C[i] = A[i] + b[i];

printf ("a[%d] =%d b[%d] =%d c[%d] =%d\n", I, a[i], I, b[i], I, c[i]);

//    }

Bubble sort

int a[5] = {10, 2, 6, 8, 4};

The number of times the outer loop controls the comparison (number of array elements-1)

for (int i = 0; i < 5-1; i++) {

Inner Loop controls the number of times each trip is compared, 22 comparison

for (int j = 0; J < 5-1-I; j + +) {

if (A[j] > a[j + 1]) {

int temp = A[j];

A[J] = a[j + 1];

A[j + 1] = temp;

}

}

}

Print array elements

for (int i = 0; i < 5; i++) {

printf ("a[%d] =%d\n", I, a[i]);

}

Randomly generates 10 [20,40] numbers and sorts 10 numbers from small to large

int a[10] = {0};

for (int i = 0; i < i++) {

int temp = arc4random ()% 21 + 20;

A[i] = temp;

printf ("a[%d] =%d", I, a[i]);

}

printf ("\ n");

for (int i = 0; i < 9; i++) {

for (int j = 0; J < 10-1-I; j + +) {

if (A[j] > a[j + 1]) {

int temp = A[j];

A[J] = a[j + 1];

A[j + 1] = temp;

}

}

}

printf ("Post-order \ n");

for (int i = 0; i < i++) {

printf ("a[%d] =%d", I, a[i]);

}

printf ("\ n");

Character array

The wording of a

Char string[6] = {' I ', ' P ', ' h ', ' o ', ' n ', ' e '};

Two

Char string1[6] = "iphone";

Live: Two types of writing are completely equivalent

No assignment when defined

int a[5] = {1}; The integer type defaults to 0

Char s[5] = {' I '}; Character type default is ' + '

Use of character arrays

STRING[2] = ' s ';

Iterate through each element of the array and print

Char String[8] = {' I ', ' P ', ' h ', ' o ', ' n ', ' e ', ' 5 ', ' s '};

for (int i = 0; i < 8; i++) {

printf ("string[%d] =%c\n", I, string[i]);

}

%s Print character array (usually add ' + ' at the end of the array)

String has 6 elements that need to be manually added at the end of the array

The string1 has 7 elements, and the system automatically adds '/' at the end of the array

If you print a string with%s, the array will be out of bounds because there is no '. '

Char string[] = {' I ', ' P ', ' h ', ' o ', ' n ', ' e '};

Char string1[] = "1phone";

Char string3[6] = {' I ', ' P ', ' h ', ' o ', ' n ', ' E '};//have 6 elements

Char string4[6] = "4phone";//There are 6 elements

printf ("String:%s\nstring1:%s\nstring3:%s\nstring4:%s\n", String, string1, string3, String4);

%s stops when it encounters '/'

STRING[2] = ' + ';

printf ("String:%s\n", string);

strlen (const char *)

Calculating the length function of a character

It's over, and ' I ' don't count into length.

Char string[10] = "I love U";

STRING[2] = ' + ';

unsigned long length = strlen (string);

printf ("Length =%lu\n", length);

strcpy (String 1, String 2)

Copy of the string

Copy each element in string 2 to string 1 until the string 2 encounters the end of

(*) string 1 to be large enough to prevent cross-border

Char str1[10] = "I love";

Char str2[10] = "You";

strcpy (str1, str2);

printf ("str1:%s\n", str1);

printf ("str2:%s\n", str2);

*/

strcat (String 1, String 2)

string concatenation function

Start with string 1 from the first ' + ' to stitch each element of string 2 into string 1 until the string 2 encounters the end

Note: The space for string 1 must be large enough to prevent out-of-bounds

Char str1[10] = "I love";

STR1[2] = ' + ';

Char str2[10] = "You";

strcat (str1, str2);

printf ("str1:%s\n", str1);

printf ("str2:%s\n", str2);

//

strcmp (String 1, String 2)

string comparison function

Subtract from the ASCII value of the element in string 1 for each element and the corresponding position string 2, if 0, to continue the comparison, and if not 0, to stop the comparison and return the difference; when the corresponding element is ' + ', the comparison stops and the result is 0.

Char str1[10] = "ABC";

Char str2[10] = "ABC";

int result = strcmp (str1, str2);

printf ("result =%d\n", result);

//

return 0;

}

C-language Array (one-dimensional, character)