&;b+c>a)
{double s=(a+b+c)/2;
printf("SS=%.10lf\n",sqrt(s*(s-a)*(s-b)*(s-c)));}
else printf("Data error!");}
执行结果:
4 5 6
SS=9.9215674165
6.源程序:
main()
{int a=3,b=4,c=5;float d=1.2,e=2.23,f=-43.56;
printf("a=%3d,b=%-4d,c=**%d\nd=%g\ne=%6.2f\nf=%-10.4f**\n",a,b,c,d,e,f);}
7.源程序:
main()
{int a,b,c,m;
scanf("%d %d %d",&;a,&;b,&;c);
m=a;a=b;b=c;c=m;
printf("%d %d %d\n",a,b,c);}
执行结果:
5 6 7
6 7 5
8.源
程序:
main()
{int a,b,c;
scanf("%d %d %d",&;a,&;b,&;c);
printf("average of %d,%d and %d is %.2f\n",a,b,c,(a+b+c)/3.);
执行结果:
6 7 9
average of 6,7 and 9 is 7.33
9.不能。修改后的源程序如下:
main()
{int a,b,c,x,y;
scanf("%d %d %d",&;a,&;b,&;c);
x=a*b;y=x*c;
printf("a=%d,b=%d,c=%d\n",a,b,c);
printf("x=%d,y=%d\n",x,y);}
6 第5章 选择结构程序设计
一、单项选择题(第113页)
1-4.DCBB 5-8.DABD
二、填空题(第115页)
1.非0 0 2.k==0
3.if (abs(x)>4) printf("%d",x);else printf("error!");
4.if((x>=1&;&;x<=10||x>=200&;&;x<=210)&;&;x&;1)printf("%d",x);
5.k=1 (原题最后一行漏了个d,如果认为原题正确,则输出k=%。)
6. 8! Right!11 7.$$$a=0 8.a=2,b=1
三、编程题(第116页)
1.有错。正确的程序如下:
main()
{int a,b,c;
scanf("%d,%d,%d",&;a,&;b,&;c);
printf("min=%d\n",a>b?b>c?c:b:a>c?c:a);}
2.源程序:
main()
{unsigned long a;
scanf("%ld",&;a);
for(;a;printf("%d",a%10),a/=10);}
执行结果:
12345
54321
3.(1)源程序:
main()
{int x,y;
scanf("%d",&;x);
if (x>-5&;&;x<0)y=x;
if (x>=0&;&;x<5)y=x-1;
if (x>=5&;&;x<10)y=x+1;
printf("%d\n",y);}
(2)源程序:
main()
{int x,y;
scanf("%d",&;x);
if(x<10) if(x>-5) if(x>=0) if(x>=5)y=x+1;
else y=x-1; else y=x;
printf("%d\n",y);}
(3)源程序:
main()
{int x,y;
scanf("%d",&;x);
if(x<10) if(x>=5)y=x+1;
else if(x>=0)y=x-1;
else if(x>-5)y=x;
printf("%d\n",y);}
(4)源程序:
main()
{int x,y;
scanf("%d",&;x);
switch(x/5)
{case -1:if(x!=-5)y=x;break;
case 0:y=x-1;break;
case 1:y=x+1;}
printf("%d\n",y);}
4.本题为了避免考虑每月的天数及闰年等
问题,故采用面向对象的程序设计。
现给出Delphi
源程序和C++ Builder源程序。
Delphi源程序:
procedure TForm1.Button1Click(Sender: TObject);
begin
edit3.Text:=format('%.0f天',[strtodate(edit2.text) -strtodate(edit1.text)]);
end;
procedure TForm1.FormCreate(Sender: TObject);
begin
Edit2.Text:=datetostr(now);
button1click(form1)
end;
C++ Builder源程序:
void __fastcall TForm1::Button1Click(TObject *Sender)
{
Edit3->Text=IntToStr(StrToDate(Edit2->Text)-StrToDate(Edit1->Text))+"天";
}
void __fastcall TForm1::FormCreate(TObject *Sender)
{
Edit2->Text=DateToStr(Now());
Button1Click(Form1);
}
执行结果:(运行于Windows下) img378.photo.163/nxgt/41463572/1219713927.jpg
5.源程序:
main()
{unsigned a,b,c;
printf("请输入三个整数:");
scanf("%d %d %d",&;a,&;b,&;c);
if(a&;&;b&;&;c&;&;a==b&;&;a==c)printf("构成等边三角形\n");
else if(a+b>c&;&;a+c>b&;&;b+c>a)
if(a==b||a==c||b==c)printf("构成等腰三角形\n");
else printf("构成一般三角形\n");
else printf("不能构成三角形\n");}
执行结果:
请输入三个整数:5 6 5
构成等腰三角形
6.源程序:
main()
{int x,y;
scanf("%d",&;x);
if(x<20)y=1;
else switch(x/60)
{case 0:y=