经过在下仔细分析，在上次break问题中我的见解是有误的。现在把刚改好的程序拿出来让大家看看顺便也加深一下对break和continue的用法的理解。
一下是以个查询某个日期是当年的第几天以及当年是否是闰年的小程序，仅供大家参考！多多指教
#include<iostream.h>
void sfsrn(int y,int m,int d)
{
    int c;
    if((y%4==0 && y%100!=0) || y%400==0)
    {
        if(m==2&&d>29)
        {
            cout<<"*****"<<"输入的日期有误"<<"*****"<<endl;
        }
        else
        {
            switch (m)
            {
                case 1: c=d;break;
                case 2: c=31+d;break;
                case 3: c=60+d;break;
                case 4: c=91+d;break;
                case 5: c=121+d;break;
                case 6: c=152+d;break;
                case 7: c=182+d;break;
                case 8: c=213+d;break;
                case 9: c=244+d;break;
                case 10: c=274+d;break;
                case 11: c=305+d;break;
                case 12: c=335+d;break;
            }
            cout<<"今年是闰年"<<endl;
            cout<<"今天是第"<<c<<"天"<<endl;
        }
    }
    else
    {
        if(m==2&&d>28)
        {
            cout<<"*****"<<"输入的日期有误"<<"*****"<<endl;
        }
        else
        {
            switch (m)
            {
                case 1: c=d;break;
                case 2: c=31+d;break;
                case 3: c=59+d;break;
                case 4: c=90+d;break;
                case 5: c=120+d;break;
                case 6: c=151+d;break;
                case 7: c=181+d;break;
                case 8: c=212+d;break;
                case 9: c=243+d;break;
                case 10: c=273+d;break;
                case 11: c=304+d;break;
                case 12: c=334+d;break;
            }
            cout<<"今年是平年"<<endl;
            cout<<"今天是第"<<c<<"天"<<endl;
        }
    }
}
void main()
{
    cout<<"想要终止本程序请输入 0 0 0"<<endl;
    cout<<"请输入想要查询的日期"<<endl;
    int y,m,d;
while(1)
{
    cout<<"请输入日期：";
    cin>>y>>m>>d;
    if(y==0&&m==0&&d==0)
        break;
    if(y==0||m>12||d<1||d>31||m==4&&d>30||m==6&&d>30||m==9&&d>30||m==11&&d>30)
    {
        cout<<"输入的日期有误"<<endl;
        continue;
    }
    else
    {
   
        sfsrn(y,m,d);
    }
}
}

说的好!虽然现在还没试但一定可以。我回去试试,

回来试了一下，的确可以，不过你的程序少了一个主函数。主函数需要做的还是挺多的。
你子函数中第一个if(m==2&&d>29)其中29应该改为28平年二月只有28天。我把我改过的程序在贴出原来看看。
#include<iostream.h>
void sfsrn(int y,int m,int d)
{
    int c;
        switch (m)
            {
                case 1: c=d;break;
                case 2: c=31+d;break;
                case 3: c=59+d;break;
                case 4: c=90+d;break;
                case 5: c=120+d;break;
                case 6: c=151+d;break;
                case 7: c=181+d;break;
                case 8: c=212+d;break;
                case 9: c=243+d;break;
                case 10: c=273+d;break;
                case 11: c=304+d;break;
                case 12: c=334+d;break;
            }
        if((y%4==0&&y%100!=0)||(y%400==0))
        {
            cout<<"今年是闰年"<<endl;
            if(m>2)
            {
                cout<<"今天是第"<<c+1<<"天"<<endl;
            }
            else
            {
                cout<<"今天是第"<<c<<"天"<<endl;
            }
        }
        else
        {
            cout<<"今年是平年"<<endl;
            cout<<"今天是第"<<c<<"天"<<endl;
        }

}
void main()
{
    cout<<"想要终止本程序请输入 0 0 0"<<endl;
    int y,m,d;
while(1)
{
    cout<<"请输入要查询的日期：";
    cin>>y>>m>>d;
    if(y==0||m==0||d==0)
    {
        break;
    }
    if(m>12||d<1||d>31||m==4&&d>30||m==6&&d>30||m==9&&d>30||m==11&&d>30)
    {
        cout<<"输入的日期有误"<<endl;
        continue;
    }
    else if(y%4==0&&y%100!=0||y%400==0)
    {
        if(m==2&&d>29)
        {
            cout<<"输入的日期有误"<<endl;
            continue;
        }
        else
        {
            sfsrn(y,m,d);
            continue;
        }

    }
    else if(m==2&&d>28)
    {
        cout<<"输入的日期有误"<<endl;
        continue;
    }
    else
    {
   
        sfsrn(y,m,d);
    }
}
}