算法设计与问题分析

计算从20100101日起开始"三天打鱼两天晒网"，求出在以后的某一天是"打鱼"or"晒网"

即1.计算从20100101日起至指定日期的天数，分别求从2010至指定日期前一年的天数(day_year)+从该年一月到前一月的天数(day_month)+该月指定日期的天数(today.day)=相差日期(diff);

2,用相差日期(diff)%5计算余数判断该天是"打鱼"还是"晒网"

流程图

源程序：

#include #include struct Date

{

int year;

int month;

int day;

};

int DateDiff(FILE* in,FILE* out)

{

struct Date today,term;

term.month = 12;

term.day =31;

long date;

while( fscanf(in,"%ld",&date) != EOF)

{

/*针对读in.txt文件做出测试

printf("%ld\n",date);

*/

int diff,day_year,day_month=0;//sum为由20100101至指定日期的总天数

int leap;

int n = 0; //由20100101至指定日期共经过多少个闰年

static int mon[13] = {0,31,28,31,30,31,30,31,31,30,31,30,31};//每月的天数

fscanf(in,"%d",&date);

today.year = date/10000; //将输入日期年,月,日分开

today.month = date/100-today.year*100;

today.day = date%100;

/*对输入的日期年月日分开后的数据进行测试

printf("%d年%d月%d日\n",today.year,today.month,today.day);*/

if(today.year < 2010 || today.month < 1 || today.month > 12) //判断输入的年份和月份是否合理

{

fprintf(out,"输入的日期不合理");

return 0;

}

leap = ( today.year % 4 == 0 && today.year % 100 != 0 )|| today.year % 400 ; //判断输入年份是否为闰年

if(today.day < 1 || (today.day > mon[today.month] && today.month != 2)||(today.month == 2 && today.day > mon[today.month] + leap)) //判断输入日期是否符合当月天数

{

fprintf(out,"输入的日期不合理");

return 0;

}

for(int i = 2010;i < today.year;i++)

{

if(( i % 4 == 0 && i % 100 != 0 )|| i % 400 ==0) //计算由2010年至指定日期经过多少个闰年

{

n++;

}

}

day_year = (today.year - 2010) * 365 + n;

if(leap == 1)

{

for(int j = 0;j < today.month ; j++)

{

day_month += mon[j];

}

if(today.month > 2) //若输入年份为闰年且输入月份大于二计算天数加一

{

day_month += 1;

}

}

else

{

for(int k = 0;k < today.month;k++)

{

day_month += mon[k];

}

}

diff = day_year + day_month + today.day;

switch(diff % 5) //总天数除以5,若余数为1,2,3则为打鱼,其余为晒网

{

case 0:fprintf(out,"晒网 "); break;

case 1:fprintf(out,"打鱼 "); break;

case 2:fprintf(out,"打鱼 "); break;

case 3:fprintf(out,"打鱼 "); break;

case 4:fprintf(out,"晒网 "); break;

}

}

return 0;

}

int main()

{

FILE* in = fopen("in.txt","r");

/*针对文件是否打开且打开是否为空做出测试

if (in != NULL)

{

printf("There are date!\n");

}

else

{

printf("no date!\n");

}*/

FILE* out = fopen("out.txt","w");

DateDiff(in,out);

fclose(in);

fclose(out);

return 0;

}

测试代码：

测试一：针对文件是否打开且打开是否为空做测试

测试二：针对读in.txt文件做出测试

测试三：对输入日期年月日分开后的数据测试