第二次作业：编写一个四则运算的"软件"

#include <stdlib.h>
#include <stdio.h>
#include <time.h>int question_get();
int type;void main( void )
{
int r=0;
int e=0;
int answer;
int n;
srand( (unsigned)time( NULL ) );
loop:printf( "请选择要进行测试的题目种类：" );
printf( "\n1.加法运算\n2.减法运算\n3.乘法运算\n4.除法运算\n5.退出运算\n" );
printf("\t\t\t请选择(1-5):");
scanf( "%d", &type ); while( 1 )
{
int temp;
int flag;
answer = question_get();
printf( "请回答：\n" );
scanf( "%d", &temp ); while( temp!=answer )
{
e++;
printf( "\n答案错误,再接再厉，请您重做\n" ); scanf( "%d", &temp ); }
r++;
printf( "\n恭喜你！回答正确\n" ); printf( "若继续请按1，退出请按0\n" );
scanf( "%d", &flag ); while( flag!=0&&flag!=1 )
{
printf( "按其它键无效\n" );
scanf( "%d", &flag );
}
if( flag==0 )
break;
else
printf("您共回答了%d道题，其中正确的有%d道，错误的有%d道\n",e+r,r,e);
goto loop;
}
} int question_get()
{
int a,b,c;
loop: if( type==1 )
{
a=rand()%99;
b=99-a;
b=rand()%b;
printf( "%d + %d = ?", a, b );
return (a+b); }
else if( type==2 )
{
b=rand()%99;
c=99-b;
c=rand()%c;
printf( "%d - %d = ?", b+c, b );
return(c);
}
else if( type==3 )
{
a=rand()%10;
b=50-a;
b=rand()%b;
printf( "%d * %d = ?", a, b );
return(a*b);
}
else if( type==4 )
{
b=rand()%50;
c=100/b;
while( 1 )
{
c=rand()%c;
if( c!=0 )
break;
}
printf( "%d / %d = ?", b*c, b );
return(c);
}
else if( type==5 )
{
printf("\t\t\t退出系统\n");
system("pause");
exit(0);
}
else if( type==0||type>5 )
{
printf("\t\t\t输入错误，请输入1-5内的数字\n");
printf("\t\t\t请选择(1-5):");
scanf( "%d", &type );
goto loop;
} }