程序代码：

#include <stdio.h>
#include <stdlib.h>
float sum;
void lock()
{
    long int a;
    printf("请输入密码!\n");
    scanf("%d",&a);
    if(a==123456)
    {printf("密码输入正确，欢迎进入家庭理财系统!\n\n\n\n\n");}
    else
    {printf("密码输入错误!\n");return;}
}
void calculator()
{int ri, repeat;
int op1, op2, res;
char open;
scanf("%d", &repeat);
for(ri=1; ri<=repeat; ri++){
scanf("%d", &op1);
open= getchar();
res=op1;
while(open!='='){
scanf("%d",&op2);
if(open=='+')
res=res+op2;
if(open=='-')
res=res-op2;
if(open=='*')
res=res*op2;
if(open=='/')
res=res/op2;
open=getchar();}
printf("%d\n", res);
}
void inquire about()
{printf("当前余额为:%d元:\n",sum);}
void ncome();
{float x;

 printf("请输入进账数额:\n");

 scanf("%f",&x);

 sum=sum+x;

 printf("按任意键返回......");

 getchar();
}
void disburse()
{float x;

 printf("请输入支出数额:\n");

 scanf("%f",&x);

 sum=sum-x;

 printf("按任意键返回.......");

 getchar();

 return;
}
void account activity()
{int x;

 printf("***********************************\n");

 printf("1.支出 2.进账 3.退出\n");

 printf("***********************************\n");

 scanf("%d",&x);

 switch(x)

 {case 1:  disburse();break;
  case 2:  ncome();break;
  case 3:  printf("欢迎使用，再见!\n");break;break;
  case 4:  inquire about();break;

 }
}
void password()
{
    long int a;
    printf("请输入密码!\n");
    scanf("%d",&a);
    if(a==123456)
    {printf("密码输入正确，欢迎进入家庭理财系统!\n\n\n\n\n");}
    else
    {printf("密码输入错误!\n");break;}
}
void main()
{

 password();

 int x;

 printf("\n******************************\n");

 printf("\n家庭理财系统1.0 by sunyh1999\n");

 printf("\n******************************\n");

 printf("请选择管理项目:\n");

 printf("1.详细账目输入\n");

 printf("2.查询当前余额\n");

 printf("3.小工具（计算器）\n");

 printf("4.锁定管理系统\n");

 printf("5.退出\n");

 scanf("%d",&x);

 switch(x)

 {case 1: account activity();break;
  case 2: inquire about break;
  case 3: calculator();break;
  case 4: lock();break;
  case 5: printf ("欢迎再次使用，再见！");break; break;
  default:printf ("输入错误！");break; break;

 }
}