Detailed explanation of typical application code of C language array - master enters by mistake (step-by-step code explanation)

Preface ：

        This article is self-study C Learning code summarized by oneself in the language process , Gradually elaborate on the instructions , Suitable for learning zero basic programming 、 Foundation to consolidate memories , Not suitable for masters to learn , The purpose of sending this is also to exchange and learn C Language experience , All say C Language is the basic language of all languages , By knowing one method you will know all , I believe the topic that countless leaders in front have proved ,C Language is the cornerstone of all programming languages . The learning of programming will not be stingy with the knowledge points summarized by staying up late , I hope it can help you who are reading .

Catalog

Preface ：

1. One dimensional array definition ：

1.1 Basic code cases ：

2. Detailed code explanation case ：

2.1 Detailed code case + explain

2.2 Typical cases bubble sort detailed code + Explain

 2.3 Explanation of typical application code — recursive ：

2.4 Typical application code + Explain in detail ：

3. matters needing attention ：

---

1. One dimensional array definition ：

stay C The use of arrays in languages must be defined first .

One dimensional arrays are defined as ： Type specifier Array name [ Constant expression ].

among , A type specifier is any basic or constructive data type . The array name is a user-defined array identifier .

The constant expression in square brackets represents the number of data elements , Also known as the length of an array .

1.1 Basic code cases ：

int a[10]; /*  Description integer array a, Yes 10 Elements  */

float b[10], c[20]; /*  Explain real arrays b, Yes 10 Elements , Real array c, Yes 20 Elements  */

char ch[20]; /*  Description character array ch, Yes 20 Elements  */

2. Detailed code explanation case ：

#include <stdio.h>
#include <stdlib.h>
/* Array ：
   1. Arrays have the same data type , And the address is continuous —— For storage needs 
   2. Arrays are ordered —— Convenient for us to use （ Storage is stored in sequence ）
   3. The number of subscripts of array elements is called dimension . According to different dimensions , Can be divided into one-dimensional arrays 、 Two dimensional array 、 Multidimensional arrays 
   [] A few brackets have several dimensions 

    Definition ：
    One dimensional array 
   1）
    Definition ： Type character   Array name [ Constant expression ]
    Type character  —  Specify what kind of data the array stores 
    Array name  —  It can be similarly understood as variable name 
    Constant expression  —  Specify the number of array elements 
   2） Array names are similar to variable names , All need to follow the identifier rules 
    When defining an array, we need to specify the number of elements in the array , That is, numbers are required in square brackets 
    When using an array, it can be a variable , It can also be a constant 
    Elements in an array can be used like variables 
    Don't cross the bounds when using arrays （ Array subscripts and constants are equal , There are as many elements as there are , Subscript from 0 Start ）

*/
// Define an integer one bit array , The subscript of array element is from 0 Start 
/*
   problem ：int a[10],a[0]—a[9] Assign values in sequence 0-9, How to realize this method ？
  int main()
{
int a[10];
int i;
for(i=0;i<10;i++){
    a[i] = i;
printf(" %d\n",a[i]);
}
for(i=9;i>=0;i--){
    a[i] = i;
  printf(" %d\n",a[i]);
}
    return 0;
}


*/
/*
  1） Assign values while defining a one-dimensional array , It's called array initialization 
  2） If the global array is not initialized , By default, the system considers it to be assigned a value 0
  3） When assigning initial values to all array elements , You can not specify the array length 
  4) Local initialization , front 5 Each element has its initial value , The following elements are assigned a value of 0


 Initialization of one dimensional array ：
    initialization ： That is, assign initial values while defining    Such as ： int a=[10]={1,2,3,4,5,6,7,8,9,10}
*/
//1. All arrays are initialized （ Global initialization ）

int main(){
   int a[10]= {1,2,3,4,5,6,7,8,9,10};
   int i;
   for(i=0;i<10;i++){
    printf("%d \n",a[i]);
   }

}// Please correct , thank you ！

 

2.1 Detailed code case + explain

#include <stdio.h>
#include <stdlib.h>

int main()
{
  /*
  // problem ：
  1） Given a one-dimensional array , Find the maximum value in the array .
  // Solution ：“ The arena ”
   Martial arts competition for marriage ：1 People stand on the challenge arena —— Compare the rest ,


  2) Flip the array 
  1 2 3 4 5 6 7
  7 6 5 4 3 2 1


   3) How to sort arrays 
   int a[6] {5,7,9,10,3,1} 1,3,5,7,9,10


  */
      /*
    //1. Define a one-dimensional array , At the same time, you need to initialize 
  int a[10]={7,4,9,8,5,34,28,45,56,97};
  //2. Determine the champion , Given the initial maximum 
  int max=a[0];
  //3. Loop traversal , Compare the values of each element in turn ,
// If the element value ratio max It's worth a lot , be max The value of is updated to this number , Otherwise it doesn't change .
  int i;
  for(i=0;i<10;i++)
  {
      if(a[i]>max){
        max=a[i];
      }

  }
     printf(" The maximum value is ：%d\n",max);
  */

    // Example 2 ： Fallible method ： Use reverse order output （ Not an option ）：
    /*
    int a[6] = {1,2,3,4,5,6};
    // Array considerations ：a[] Brackets indicate that there are several elements ,
    // You need to define the value later , Otherwise, it will be assigned , from “0” Start counting the first number 
    int i;
    for(i=5;i>=0;i--){
        printf("%d ",a[i]);// Output ：6 5 4 3 2 1

    }
    printf("\n");
    for(i=0;i<6;i++)
    {
        printf("%d ",a[i]);// Output ：1 2 3 4 5 6
    }
    // This method only changes the order of output values , It didn't happen 1 To 6 Reversal of values between values 

    */

    // Example 2 correct solution ： The flip of the array can be realized through the exchange of elements 
    //1 and 6 in ,2 and 5 in ,3 and 4 in ,
    //1 2 3 4 5 6
    //6 5 4 3 2 1
    //a[0] and a[n-1] in  a

    /*
  sizeof()  Is a memory capacity measurement function , The function is to return the size of a variable or type （ In bytes ）;
  stay C In language ,sizeof() It is an operator to judge the data type or expression length .
    */



    /*
    int a[6]= {1,2,3,4,5,6};
    int i=0;
    int tmp;// Use an idle variable to exchange 
    int j=sizeof(a)/sizeof(int)-1;// The elements in the computer are from 0 Starting number ,0 It's the first element 
    while(i<j){


         tmp = a[i];
         a[i] = a[j];
         a[j] = tmp;
         i++;
         j--;
    }
    for(i=0;i<6;i++)
    {
        printf("%d ",a[i]);
    }
   printf("\n");
   */

   /*
   //3) How to sort arrays 
   int a[6] {5,7,9,10,3,1} 1,3,5,7,9,10


   // Using bubble sort 
   */
   int a[6] =  {5,7,9,10,3,1};

   /*
   // Bubble sorting process , Compare the size several times 
   int a[6] =  {5,7,9,10,3,1};
   1   5=n-1   5 7 9 3 1 10
   2   4=n-2   5 7 3 1 9 10
   3   3=n-3   5 3 1 7 9 10
   4   2=n-2   3 1 5 7 9 10
   5   5=n-1   1 3 5 7 9 10

   */


   int i;// Number of sortings 
   int j;// Compare the values of two adjacent numbers 
   int tmp;// Define an exchange variable for temporary Exchange 
   int n = sizeof(a)/sizeof(int);
   for(i=0;i<n;i++){
    for(j=0;j<n-1-i;j++)
    // Exchange of elements （ The premise is that two adjacent numbers , The former is bigger than the latter ）
        {
        if(a[j]>a[j+1]){
            tmp = a[j];
            a[j] = a[j+1];
            a[j+1] = tmp;
        }
    }
   }
// Output results 
for(i=0;i<n;i++)
{
    printf("%d ",a[i]);
}
    return 0;
}
// If there is any mistake, please correct it , thank you .

2.2 Typical cases bubble sort detailed code + Explain

#include<stdio.h>
void main()
{
 int n[10] = { 25,35,68,79,21,13,98,7,16,62 };// Define a size as 10 Array of 
 int i, j,k,temp;
 for (i = 1; i <= 9; i++)// The outer cycle is the number of rounds compared , There are... In the array 10 Number , Then it should be more 10-1=9 round 
 {
  for (j = 0; j <= 9 - i; j++)// The inner loop compares the number of comparisons in the current round , for example ： The first round of comparison 9-1=8 Time , The second round of comparison 9-2=7 Time 
  {
   if (n[j] > n[j + 1])// If two adjacent numbers are in reverse order , Then switch places 
   {
    temp = n[j];
    n[j] = n[j + 1];
    n[j + 1] = temp;
   }
  }
  printf(" The first %d The data sorting after the sorting is completed :\n",i);
  for (k = 0;k < 10; k++)
   printf("%-4d", n[i]);
  printf("\n");
 }
 printf(" The order of numbers after sorting :\n");
 for (i = 0; i < 10; i++)
  printf("%-4d", n[i]);
 printf("\n");
}
// Please correct 

 2.3 Explanation of typical application code — recursive ：

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

void PrintN(int N)
{
 if (N)
 {
 PrintN(N-1);
 printf("%d\n",N);
 }
 return;
}

void main()
{
 int N;
 clock_t start,finish;
 double duration;
 printf("please input N:\n");
 scanf("%d",&N);
 start = clock();
 PrintN(N);
 finish = clock();
 duration = (double)(finish - start) / CLOCKS_PER_SEC;
 printf("%f seconds\n",duration );
 return;
}
// Please correct 

2.4 Typical application code + Explain in detail ：

#include <stdio.h>


#include <stdlib.h>
/*
    One dimensional array initialization 
    initialization ： Is to assign initial values while defining , Such as 
   int a[10] = {1,2,3,4,5,6,7,8,9,10}
    If you don't assign a value, it will be assigned automatically 

    The array name of a one-dimensional array 
   1. Array name is a constant 
   2. Array name is the first address of an array element 
   3.sizeof（ Array name ） In fact, the total size of the array is calculated 

 problem ：
    1） Given an array , Find the maximum value of the array 
     resolvent ： Given an initial value , Compare the size 
     Definition ：i  and  max To compare 

  int a[10] = {10,20,90,31,32,44,55,66,10,23};
    int max = a[0];
    int i;
    for(i=0;i<10;i++){
        if(a[i]>max){
        max = a[i];
    }
    }
    printf(" The larger number in the array is ： %d\n",max);


     problem 2 ： Realize array flip 、
     Use the exchange method to realize the element position exchange in the array , Array flip .

*/


int main()
{
int a[10] = {1,2,3,4,5,6,7,8,9,10};
int i=0;
int tmp;
int j = sizeof(a)/sizeof(int)-1;
while (i<j){
    tmp  = a[i];
    a[i] = a[j];
    a[j] = tmp;
    i++;
    j--;
}
for(i=0;i<10;i++){
    printf("%d ",a[i]);
}



    return 0;
}

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Refined programming development partner .

3. matters needing attention ：

For the array type description, the following points should be noted ：

• The type of array actually refers to the value type of array elements .
• For the same array , All data elements of the same type .
• The writing rules of array name should conform to the writing rules of identifier .
• Array names cannot be the same as other variable names .

C Language learning begins with arrays and becomes more and more difficult , Good programmers = talent + Practice hard

Less lofty pursuit , More down-to-earth persistence .