字符串使用、函数指针、内存分配

来源：互联网发布：关系数据库中关系是指编辑：程序博客网时间：2024/06/05 14:34

#include "stdafx.h"#include <stdlib.h>  #include <windows.h>//函数指针int plus(int a, int b) {return a + b;}int minus(int a, int b) {return a - b;}int plus2(int *a, int *b) {return *a + *b;}int minus2(char * a, char *b) {return 0;}int main(){int result;int c = 3;int d = 5;int(*calc)(int a, int b);int(*calc2)(void *a, void *);int * p(int a, int b);//calc = plus;calc = minus;result = calc(3, 5);//-2calc2 = (int(*)(void *, void *))plus2;result = calc2(&c, &d);//8system("pause");return 0;}//内存分配// 40.3M//40M 手动分配，0.3M 哪来的？ 程序的二进制文件void mem(){}int main(){//40M的数组//栈溢出int t = 1000;int aa[10];int ab[100];/*while (1){mem();Sleep(2000);}*/int *a = (int *)malloc(sizeof(int)* 1024 * 1024);if (a == NULL){printf("内存不够，请温柔\n");}a[0] = 5;*a + 1;printf("%d\n", sizeof(a));printf("%#x", a);char *ch = (char *)malloc(sizeof(char)* 1024);ch + 1;a = (int *)malloc(sizeof(int)* 1024 * 1024 * 2);free(a);a = NULL;printf("a address: %#x,", a);// 如果不进行a = NULL;那么，a 就是一个野指针system("pause");}int main() {int * b = (int *)calloc(4, 100 * sizeof(int));if (b == NULL){printf("内存不够，请温柔\n");}//printf("%d\n", sizeof(a));printf("%#x", b);system("pause");return 0;}

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