Function and usage of malloc function in C language

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About C Language malloc function

• Function introduction
• Application, for example, 1
• Application, for example, 2

Function introduction

malloc（memory allocation） Chinese name ： Dynamic memory allocation It is used to apply for a continuous memory block area of specified size to void* Type returns the address of the allocated memory area , When you can't know the exact location of memory , Want to bind real memory space , We need to use dynamic memory allocation .

Application, for example, 1

About C Language dynamic application array （ The type of shaping data ） Application of space

#include<stdio.h>
#include<malloc.h>

void A()
{ 
   
	int n;// Number of array elements 
	int *add;
	scanf("%d",&n);
	add=(int *)malloc(sizeof(int)*n);// Memory application 
	for(int i=0;i<n;i++)
	{ 
   
		scanf("%d",&add[i]);
	}
	for(int i=0;i<n;i++)
	{ 
   
		printf("%d",add[i]);
	}
}

int main()
{ 
   
	A();
	return 0;
}

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Application, for example, 2

C Language dynamic application array （ Structure ） Application of space

#include<stdio.h>
#include<stdlib.h>
#include<malloc.h>// contain malloc Function header file 

struct Item// Defining structure 
{ 
   
	char name[20];
	int num;	
};

struct Item *I;// apply Item Pointer to type 

int A()// Make a memory request 
{ 
   
	int i,j;
	int n;// Number of applications 
	scanf("%d",&n);
	I=(struct Item*)malloc(sizeof(struct Item)*n);
	return n;	
}

int Input()// Data input function 
{ 
   
	int n=A();
	int i,j;
	for(i=0;i<n;i++)
	{ 
   
		printf("%d Name:",i+1);
		scanf("%s",&I[i].name);
		printf("num:\n");
		scanf("%d",&I[i].num);
	}
	return n;	
}

void output()// Data output function 
{ 
   
	int n=Input();
	for(int i=0;i<n;i++)
	{ 
   
		printf("%d |",i);
		printf("Name:%s ",I[i].name);
		printf("num:%d\n",I[i].num);
	}
}

int main()
{ 
   
	output();
	return 0;
}

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