C语言_结构体

结构体用作函数参数

传递结构体指针

传递结构体的数值

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#include<stdio.h>
#include<string.h>

struct namect{

    char fname[20];
    char lname[20];
    int letters; 
}; 

struct namect getinfo(void);
struct namect makeinfo(struct namect);
void showinfo(struct namect);

int main(void)
{
    struct namect person;
    person=getinfo();
    person=makeinfo(person);
    //makeinfo(person);
    showinfo(person);
    return 0;
}

struct namect  getinfo(void)
{
    struct namect temp;
    printf("please enter you first name.\n");
    gets(temp.fname);
    printf("please enter you last name.\n");
    gets(temp.lname);
    return temp; 
}

struct namect makeinfo(struct namect info)
{
    info.letters=strlen(info.fname)+strlen(info.lname);
    return info;

}
void showinfo (struct namect info)
{
    printf("%s %s ,your name contains %d letters .\n",info.fname,info.lname,info.letters);

}

程序的运行结果图如下：
     [正确的改变了letters的值](http://img.blog.csdn.net/20150905160652097)

情形2：
    如果将person=makeinfo(person)改为makeinfo(person),则运行结果如下：
     [letters得到一个随机的值](http://img.blog.csdn.net/20150905161005090)

3.结构体指针作为参数
    将结构体指针作为函数的参数，从而直接去改变letters的值，相关代码如下：

#include<stdio.h>
#include<string.h>

struct namect{

    char fname[20];
    char lname[20];
    int letters; 
}; 

struct namect getinfo(void);
void  makeinfo(struct namect *pst);
void showinfo(struct namect);

int main(void)
{
    struct namect person;
    person=getinfo();
    //person=makeinfo(person);
    //makeinfo(person);
    makeinfo(&person);   //取地运算
    showinfo(person);   、、
    return 0;
}

struct namect  getinfo(void)
{
    struct namect temp;
    printf("please enter you first name.\n");
    gets(temp.fname);
    printf("please enter you last name.\n");
    gets(temp.lname);
    return temp; 
}

 void makeinfo(struct namect *pst)
{
    pst->letters=strlen(pst->fname)+strlen(pst->lname);

}
void showinfo (struct namect info)
{
    printf("%s %s ,your name contains %d letters .\n",info.fname,info.lname,info.letters);

}