C Peimer 第16章编程习题

宏macro，这部分从前欠缺的也相当厉害，就知道个define与include，条件编译果然强大。最让我佩服的大概就是设计这些编程范式的人了，竟然想到用一个#define NDEBUG等可以截阻测试句。虽然我用的还不太熟，但真的让人思路大开……

这次的题少，仅七道，但我是分文件写的，也算熟练一下include等技术。

1.

#include <stdio.h>#include "Ch16_1.h"#include <time.h>#include <stdlib.h>int main(void) {//1//创建头文件——成功！//2/*double x1 = 3;double x2 = 2;double modi;modi = MODIFYFUN(x1, x2);printf("the final result:%lf", modi);*///3/*struct Polar polarP;struct Rect rectP;polarP.len = 2;//由1：sqrt（3）:2三角形测试成功！polarP.ang = 3.14/3;rectP = Polar2Rect(&polarP);printf("x = %lf,y = %lf", rectP.x, rectP.y);*///4/*int x = 10;TimeDelay(10);//自定义延迟函数，声明于头文件，定义于独立.cprintf("success! Function has delayed %ds", x);*///5/*int arr[NAMELEN];int times = 9;int count = 0;for (int i = 0; i < NAMELEN; i++){//初始化数组，组内元素为是否被选择arr[i] = 0;}ChooseMem(arr, NAMELEN, 9);printf("total number:%d, choose times:%d, final results:\n", NAMELEN, times);for (int i = 0; i < NAMELEN; i++){if (arr[i]==1){count++;printf("The %dth number is %d!\n", count, i + 1);}}*///6/*struct name list[12];int size = 12;fillarray(list,size);//fill letters in a random ordershowarray(list, size);qsort(list, size, sizeof(struct name), mycomp);printf("\nin an order\n\n");showarray(list, size);*///7double *p1;double *p2;p1 = new_d_array(6, 1.2, 2.3, 3.2, 4.2, 4.5, 5.6);p2 = new_d_array(4, 100.3, 5.5, 3.5, 3.1);show_array(p1, 6);printf("\nnew line\n\n");show_array(p2, 4);free(p1);free(p2);return 0;}

2.头文件

#pragma once#include <stdio.h>#include <stdlib.h>#include <stdarg.h>#define MODIFYFUN(x1,x2) 1/((1/(x1)) + (1/(x2)))#define NAMELEN 20struct Polar{double len;double ang;};struct Rect{double x;double y;};struct name{char first[NAMELEN];char last[NAMELEN];};struct Rect Polar2Rect(const struct Polar *temp);void TimeDelay(int);//5void ChooseMem(int *temp, int size, int times);//6void fillarray(struct name *ar, int n);void showarray(struct name *ar, int n);int mycomp(const void *p1, const void *p2);//7void show_array(const double ar[], int n);double * new_d_array(int n, ...);

3.

#include <stdio.h>#include "Ch16_1.h"void ChooseMem(int *temp, int size, int times) {int choice;int count = 0;srand(time(NULL));while (count < times){choice = rand() % size;if (*(temp + choice) != 1){*(temp + choice) = 1;count++;}}}

4.

#include "Ch16_1.h"#include <stdio.h>#include <stdlib.h>#include <string.h>void fillarray(struct name *ar, int n) {char temp1[NAMELEN];char temp2[NAMELEN];srand(time(NULL));int i;for (int j = 0; j < n; j++){for (i = 0; i < rand() % (NAMELEN - 5) + 3; i++){temp1[i] = rand() % 26 + 'a';}temp1[i] = '\0';strcpy((*(ar+j)).first, temp1);for (i = 0; i < rand() % (NAMELEN - 5) + 3; i++){temp2[i] = rand() % 26 + 'a';}temp2[i] = '\0';strcpy((*(ar + j)).last, temp2);}}void showarray(struct name *ar, int n) {for (int i = 0; i < n; i++){printf("%s %s\n", ar[i].first, ar[i].last);}}int mycomp(const void *p1, const void *p2) {const struct name *a1 = (const struct name *)p1;const struct name *a2 = (const struct name *)p2;if (strcmp((*a1).first,(*a2).first) > 0){return 1;}else if (strcmp((*a1).first, (*a2).first) < 0){return -1;}else{if (strcmp((*a1).last, (*a2).last) > 0){return 1;}else{return -1;}}}

5.

#include <stdio.h>#include <stdlib.h>#include <stdarg.h>void show_array(const double ar[], int n) {for (int i = 0; i < n; i++){printf("%lf\n", ar[i]);}}double * new_d_array(int n, ...) {double *p1;p1 = malloc(sizeof(double)*n);va_list temp;va_start(temp, n);for (int i = 0; i < n; i++){*(p1 + i) = va_arg(temp, double);}return p1;}

6.

#include "Ch16_1.h"#include <math.h>struct Rect Polar2Rect(const struct Polar *temp) {struct Rect rectP;rectP.x = (*temp).len*cos((*temp).ang);rectP.y = (*temp).len*sin((*temp).ang);return rectP;}

7.

#include "Ch16_1.h"#include <stdio.h>#include <time.h>void TimeDelay(int x) {double start;double divide = 0;start = clock();while (divide<x){divide = (clock() - divide) / CLOCKS_PER_SEC;}}