程序是；
#include<stdio.h>
#include<math.h>
int getBirthdayDate(int* Bmonth,int* Bday,int* Byear);
int getNowDate(int* Nmonth,int* Nday,int* Nyear);
int calculate(int* month,int* day,int* year);
void printInformation();
int main()
{
    int Bmonth,Bday,Byear;
    int Nmonth,Nday,Nyear;
    int month,day,year;

    getBirthdayDate(&Bmonth,&Bday,&Byear);
    getNowDate(&Nmonth,&Nday,&Nyear);
    calculate(&month,&day,&year);
    printInformation();
    return(0);
}
int getBirthdayDate(int* Bmonth,int* Bday,int* Byear)
{
    printf("enter the month;\n");
    scanf("%d",Bmonth);
    printf("enter the day;\n");
    scanf("%d", Bday);
    printf("enter the year;\n");
    scanf("%d", Byear);
    return;
}


int getNowDate(int* Nmonth,int* Nday,int* Nyear);
{
   printf("enter the month;\n");
    scanf("%d",Nmonth);
    printf("enter the day;\n");
    scanf("%d", Nday);
    printf("enter the year;\n");
    scanf("%d", Nyear);
    return;
}

int calculate(int* month,int* day,int* year);
{
   int Bmonth,Bday,Byear;
   int Nmonth,Nday,Nyear;
   if(Nday>=Bday)
       *day=Nday-Bday;
   else
   {
       day=(Nday+30)-Bday;
       Nmonth=Nmonth-1;
   }
   if(Nmonth>=Bmonth)
       *month=Nmonth-Bmonth;
   else
   {
       *month=(Nmonth+12)-Bmonth;
       Nyear=Nyear-1;
   }
   if(Nyear>=Byear)
       *year=Nyear-Byear;
   else
        printf("it's error!");
}

void printInformation()
{
    int Bmonth,Bday,Byear;
    int Nmonth,Nday,Nyear;
    int month,day,year;
    printf("this people Birthday is; %d-&d-%d!",Bmonth,Bday,Byear);
    printf("today is;%d-%d-%d!",Nmonth,Nday,Nyear);
    printf("his age is;%dold%dmonth%dday;",year,month,day);
    return;

}
错误提示是；

计算年龄.cpp
C:\Documents and Settings\Administrator\桌面\计算年龄.cpp(27) : error C2561: 'getBirthdayDate' : function must return a value
        C:\Documents and Settings\Administrator\桌面\计算年龄.cpp(3) : see declaration of 'getBirthdayDate'
C:\Documents and Settings\Administrator\桌面\计算年龄.cpp(32) : error C2447: missing function header (old-style formal list?)
C:\Documents and Settings\Administrator\桌面\计算年龄.cpp(43) : error C2447: missing function header (old-style formal list?)
执行 cl.exe 时出错.

计算年龄.exe - 1 error(s), 0 warning(s)

如果你都不愿意自己翻翻字典查查错误提示中的那几个单词是什么意思，那你还是别学编程了，这是在浪费时间。

+65535

我查了，就是不知道怎回事
'getBirthdayDate' : function must return a value
“getBirthdayDate”:函数必须返回一个值
see declaration of 'getBirthdayDate'
看到“getBirthdayDate”宣言
missing function header (old-style formal list?)
失踪的函数header(旧式的正式名单吗?)

我查了，就是不知道怎回事
'getBirthdayDate' : function must return a value
“getBirthdayDate”:函数必须返回一个值
see declaration of 'getBirthdayDate'
看到“getBirthdayDate”宣言
missing function header (old-style formal list?)
失踪的函数header(旧式的正式名单吗?)

连“函数必须返回一个值”这话什么意思都不懂？呵呵，算了。你的分别给我，我不想要。

最简单的改法 对于有返回值的函数 最后写return 0; 就对了

看来你对函数返回值还不了解啊 多看书罢

从简单的学起吧！看<->练！

楼主的代码我没怎么看，但是从报错的信息上看问题好像是出在int getBirthdayDate(int* Bmonth,int* Bday,int* Byear)
处，楼主定义的是一个返回值是int型的函数，那么在函数后就应该有return返回一个整型的数。



另外请教一下两位版主大神像楼主这样getBirthdayDate(&Bmonth,&Bday,&Byear);
    getNowDate(&Nmonth,&Nday,&Nyear);
    calculate(&month,&day,&year);
把变量的地址作为实参传递可以吗？我在编译器上试了好久，都没成功，是这样做不允许还是我没弄好？
请大神解惑

呵呵，原来这样真的可以。
#include<stdio.h>
#include<math.h>
int getBirthdayDate(int* Bmonth,int* Bday,int* Byear);
int getNowDate(int* Nmonth,int* Nday,int* Nyear);
int calculate(int* month,int* day,int* year);
void printInformation();
    int Bmonth,Bday,Byear;
    int Nmonth,Nday,Nyear;
    int month,day,year;
int main()
{


    getBirthdayDate(&Bmonth,&Bday,&Byear);
    getNowDate(&Nmonth,&Nday,&Nyear);
    calculate(&month,&day,&year);
    printInformation();
    return 0;
}
int getBirthdayDate(int* Bmonth,int* Bday,int* Byear)
{
    printf("enter the month;\n");
    scanf("%d",Bmonth);
    printf("enter the day;\n");
    scanf("%d", Bday);
    printf("enter the year;\n");
    scanf("%d", Byear);
    return 0;
}


int getNowDate(int* Nmonth,int* Nday,int* Nyear)
{
   printf("enter the month;\n");
    scanf("%d",Nmonth);
    printf("enter the day;\n");
    scanf("%d", Nday);
    printf("enter the year;\n");
    scanf("%d", Nyear);
    return 0;
}

int calculate(int* month,int* day,int* year)
{

   if(Nday>=Bday)
       *day=Nday-Bday;
   else
   {
       day=(Nday+30)-Bday;
       Nmonth=Nmonth-1;
   }
   if(Nmonth>=Bmonth)
       *month=Nmonth-Bmonth;
   else
   {
       *month=(Nmonth+12)-Bmonth;
       Nyear=Nyear-1;
   }
   if(Nyear>=Byear)
       *year=Nyear-Byear;
   else
        printf("it's error!");return 0;
}

void printInformation()
{
    printf("this people Birthday is; %d-%d-%d!\n",Bmonth,Bday,Byear);
    printf("today is;%d-%d-%d!\n",Nmonth,Nday,Nyear);
    printf("his age is;%dold%dmonth%dday;\n",year,month,day);
    return 0;

}
哈哈，原来地址也可以当做实参的，学习了。。
本人新手，说错勿怪，欢迎指正。。