编写一个C程序以使用动态内存分配功能来显示和添加元素。
在C语言中,库函数malloc在运行时以字节为单位分配一个内存块。它返回一个空指针,该指针指向已分配内存的基地址,并且使该内存未初始化。
void *malloc (size in bytes)
例如,
int * ptr;
ptr =(int *)malloc(1000);
int * ptr;
ptr =(int *)malloc(n * sizeof(int));
注–如果内存不是空闲的,则返回NULL。
#include<stdio.h> #include<stdlib.h> void main(){ //Declaring variables and pointers,sum// int numofe,i,sum=0; int *p; //Reading number of elements from user// printf("输入元素数: "); scanf("%d",&numofe); //Calling malloc() function// p=(int *)malloc(numofe*sizeof(int)); /*Printing O/p - We have to use if statement because we have to check if memory has been successfully allocated/reserved or not*/ if (p==NULL){ printf("Memory not available"); exit(0); } //Printing elements// printf("Enter the elements : \n"); for(i=0;i<numofe;i++){ scanf("%d",p+i); sum=sum+*(p+i); } printf("\nThe sum of elements is %d",sum); free(p);//Erase first 2 memory locations// printf("\nDisplaying the cleared out memory location : \n"); for(i=0;i<numofe;i++){ printf("%d\n",p[i]);//Garbage values will be displayed// } }输出结果
输入元素数: 5 Enter the elements : 23 45 65 12 23 The sum of elements is 168 Displaying the cleared out memory location : 10753152 0 10748240 0 23