结构、指针和malloc()

作者：追风剑情发布于：2020-3-9 18:08 分类：C

示例

//Visual Studio中加上这句才可以使用scanf()
//否则只能使用scanf_s()
#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <string.h>
#include <ctype.h>
//malloc()、free()
#include <stdlib.h>
#include <time.h>
 
#define SLEN 81
struct namect {
	char * fname;
	char * lname;
	int letters;
};
 
void getinfo(struct namect *);
void makeinfo(struct namect *);
void showinfo(const struct namect *);
void cleanup(struct namect *);
char * s_gets(char * st, int n);
 
//argc: 参数个数 argv[]: 参数数组
//int main(int argc, char **argv)
int main(int argc, char *argv[])
{
	struct namect person;
 
	getinfo(&person);
	makeinfo(&person);
	showinfo(&person);
	cleanup(&person);
 
	system("pause");
	return 0;
}
 
void getinfo(struct namect * pst)
{
	char temp[SLEN];
	printf("Please enter your first name.\n");
	s_gets(temp, SLEN);
	// 分配内存
	pst->fname = (char *)malloc(strlen(temp) + 1);
	// 把名拷贝到动态分配的内存中
	strcpy(pst->fname, temp);
	printf("Please enter your last name.\n");
	s_gets(temp, SLEN);
	pst->lname = (char *)malloc(strlen(temp) + 1);
	strcpy(pst->lname, temp);
}
 
void makeinfo(struct namect * pst)
{
	pst->letters = strlen(pst->fname) +
		strlen(pst->lname);
}
 
void showinfo(const struct namect * pst)
{
	printf("%s %s, your name contains %d letters.\n",
		pst->fname, pst->lname, pst->letters);
}
 
// 释放内存
void cleanup(struct namect * pst)
{
	free(pst->fname);
	free(pst->lname);
}
 
char * s_gets(char * st, int n)
{
	char * ret_val;
	int i = 0;
	ret_val = fgets(st, n, stdin);
	if (ret_val) //即，ret_val != NULL
	{
		while (st[i] != '\n' && st[i] != '\0')
			i++;
		if (st[i] == '\n')
			st[i] = '\0';
		else
			while (getchar() != '\n')
				continue;
	}
	return ret_val;
}