谭浩强 《C程序设计》 第三版 第五章习题答案 （修正）

第五章习题答案
5.1
所谓关系运算实际上是比较运算，例如a>3是一个关系表达式，大于号是一个关系运算符，如果a的值是5，则满足给定的”a>3”条件，因此关系表达式的值“真“。。。
用逻辑运算符将关系表达式或逻辑表达式连接起来的式子就是逻辑表达式。
5.2 C语言编译系统在表示逻辑运算结果时，以数值1代表“真“，以0代表”假“，但在判断一个量是否为”真“时，以0代表”假“，以非0代表”真“，即将一个非零的数值认作为”真“。
5.3

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1
5.4

//practice 5.4
void main()
{
        
int a,b,c,t,max;
        
scanf("%d%d%d",&a,&b,&c);
        
max=a;
        
if(max<b)
        
{
                  
t=max;
                  
max=b;
                  
b=t;
        
}
        
if(max<c)
        
{
                  
t=max;
                  
max=c;
                  
c=t;
        
}
        
printf("%2d/n",max);
}
void main()
{
        
int a,b,c,temp,max;
        
scanf("%d%d%d",&a,&b,&c);
        
temp=(a>b)?a:b;
        
max=(temp>c)?temp:c;
        
printf("%3d/n",max);
}
//practice 5.5
void main()
{
        
double x,y;
        
scanf("%lf",&x);
        
if(x-1<1e-6)
        
{
        
   y=x;   
        
}
        
else if( x-1>=1e-6 && x-10<1e-6)
        
{
                  
y=2*x-1;
        
}
        
else if( x-10>=1e-6)
        
{
                  
y=3*x-11;
        
}
        
printf("%3lf/n",y);
}
//practice 5.6
void main()
{
        
double score;
        
char grade;
        
printf("请输入成绩:/n");
        
scanf("%lf",&score);
        
while(score>100 || score<0)
        
{
                  
printf("/n 输入有误，请重新输入:/n");
                  
scanf("%lf",&score);
        
}
        
switch((int)score/10)
        
{
        
case 9:grade='A';break;
        
case 8:grade='B';break;
        
case 7:grade='C';break;
        
case 6:grade='D';break;
        
default:grade='E';
        
}
        
printf("输入的成绩是%lf,相应的等级是%c/n",score,grade);
}
//pra 5.7
//第一种方法
void main()
{
        
int num,i;
        
char str[200]; 
        
sprintf(str,"%d",num);    
        
printf("the size of the integer is %d/n",strlen(str));
        
puts(str);
        
putchar('/n');
        
i=strlen(str)-1;
        
while(i>=0)
        
{
                  
putchar(*(str+i));
                  
i--;
        
}
   
putchar('/n');
}*/
//第二种方法
//pra 5.7
void main()
{
        
int num,size;
        
int indiv,ten,hundred,thousand,ten_thousand;
        
scanf("%d",&num);
        
while(num>99999 || num<=0)
        
{
                  
printf("/n输入有误，请重新输入:/n");
                  
scanf("%d",&num);
        
}
        
if(num>9999)
        
{
                  
size=5;
        
}
        
else if(num>999)
        
{
                  
size=4;
        
}
        
else if(num>99)
        
{
                  
size=3;
        
}
        
else if(num>9)
        
{
                  
size=2;
        
}
        
else
        
{
                  
size=1;
        
}
        
printf("size=%2d/n",size);
   
printf("每位数字为:/n");
        
ten_thousand=num/10000;
        
thousand=num%10000/1000;
        
hundred=num%10000%1000/100;
        
ten=num%10000%1000%100/10;
        
indiv=num%10000%1000%100%10;
        
switch(size)
        
{
                  
case 5:printf("%2d,%2d,%2d,%2d,%2d/n",ten_thousand,thousand,hundred,ten,indiv);
                           
printf("反序为:/n");
                           
printf("%2d,%2d,%2d,%2d,%2d/n",indiv,ten,hundred,thousand,ten_thousand);
                           
break;
                  
case 4:printf("%2d,%2d,%2d,%2d/n",thousand,hundred,ten,indiv);
                           
printf("反序为:/n");
                           
printf("%2d,%2d,%2d,%2d/n",indiv,ten,hundred,thousand);
                           
break;
                  
case 3:printf("%2d,%2d,%2d/n",hundred,ten,indiv);
                           
printf("反序为:/n");
                           
printf("%2d,%2d,%2d/n",indiv,ten,hundred);
                           
break;
                  
case 2:printf("%2d,%2d/n",ten,indiv);
                           
printf("反序为:/n");
                           
printf("%2d,%2d/n",indiv,ten);
                           
break;
                  
case 1:printf("%2d/n",indiv);
                           
printf("反序为:/n");
                           
printf("%2d/n",indiv);
                           
break;
                  
default :printf("ERROR/n");
        
}
}
//pra 5.8
//IF
语句的写法
/*int main()
{
        

        
double I;//Interest
        
double J;//奖金
        
printf("单位
万元 /n");

        
scanf("%lf",&I);
        
if(I<=10)
        
{
                  
J=10*0.1;
        
}
        
else if((I>10)&&(I<=20))
        
{
        
    J=10*0.1+(I-10)*0.075;
        
}
        
else if((I>20)&&(I<=40))
        
{
                  
J=10*0.1+10*0.075+(I-20)*0.05;
        
}
        
else if((I>40)&&(I<=60))
        
{
                  
J=10*0.1+10*0.075+20*0.05+(I-40)*0.03;
        
}else if((I>60)&&(I<=100))
        
{
                  
J=10*0.1+10*0.075+20*0.05+20*0.03+(I-60)*0.015;
        
}
        
else if(I>100)
        
{
                  
J=10*0.1+10*0.075+20*0.05+20*0.03+40*0.015+(I-100)*0.01;
        
}/
        
printf("%2lf/n",J);
        

        
return 0;
}*/
int main()
{
        

        
double I;//Interest
        
double J;//奖金
        
int c;
        
printf("单位
万元 /n");

        
scanf("%lf",&I);
        
c=(int)I/10;
        
if(c>10)
        
{
                  
c=10;
        
}
        
switch(c)
        
{
                  
case 0:J=10*0.1;break;
                  
case 1:J=10*0.1+(I-10)*0.075;break;
                  
case 2:
                  
case 3:J=10*0.1+10*0.075+(I-20)*0.05;;break;
                  
case 4:
                  
case 5:J=10*0.1+10*0.075+20*0.05+(I-40)*0.03;break;
                  
case 6:
                  
case 7:
                  
case 8:
                  
case 9:J=10*0.1+10*0.075+20*0.05+20*0.03+(I-60)*0.015;break;
                  
case 10:J=10*0.1+10*0.075+20*0.05+20*0.03+40*0.015+(I-100)*0.01;break;
                  
default:printf("error/n");
        
}        printf("%2lf/n",J);
        
return 0;
}
5.9
此题就是两两排序。。。略
5.10

// 5.10
void main()
{
        
double x,y;
        
scanf("%lf%lf",&x,&y);
        
if(fabs(x)>=1 && fabs(x)<=3 && fabs(y)>=1 && fabs(y)<=3)
        
{
                  
printf("height is 10/n");
        
}
        
else
        
{
                  
printf("height is 0/n");
        
}
}