C函数间指针传递演示

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#define SLEN 81

struct namect {
    char * fname; //定义字符指针
    char * lname;
    int letters;
};

void getinfo(struct namect *); //传指针分配内存
void makeinfo(struct namect *);
void showinfo(const struct namect *); //只显示结构内容不能修改结构变量
void cleanup(struct namect *);
char * s_gets(char * st, int n);

int main(void)
{
    struct namect person;
    getinfo(&person);
    makeinfo(&person);
    showinfo(&person);
    cleanup(&person);

    return 0;
}

void getinfo(struct namect * pst)
{
    char temp[SLEN];
    printf("输入英文的姓\n");
    s_gets(temp, SLEN);
    //分配内存
    pst->fname = (char *) malloc(strlen(temp) + 1);
    //把名子拷贝到分配的内在中
    strcpy(pst->fname, temp);
    printf("输入英文的名\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, 你的 %d 字母\n", pst->fname, pst->lname, pst->letters);
}

void cleanup(struct namect * pst)
{
    free(pst->fname);
    free(pst->lname);
}

char * s_gets(char * st, int n)
{
    char * ret_val;
    char * find;

    ret_val = fgets(st, n, stdin);
    if(ret_val) {
        find = strchr(st, '\n');
        if(find) {
            *find = '\0';
        } else {
            while(getchar() != '\n') {
                continue;
            }
        }
    }
    return ret_val;
}