[问题]C程序课后题

robert870119 · #1

题目是：给一个不多于5位的正整数，要求：1，求出它是几位数；2，分别打印出每一位数字；3，按逆序打印出各位数字，例如原数是321，应输出321。

我是初学者，写的代码为：

#include<stdio.h>
main()
{
int sz,ww,qw,bw,sw,gw,i,n,t;
printf("请输入不多于5位的正整数\n");
scanf("%d",&sz);
{{i=sz/10000;
if(i!=0)n=5;
else i=sz/1000;
if(i!=0)n=4;
else i=sz/100;
if(i!=0)n=3;
else i=sz/10;
if(i!=0)n=2;
else n=1; }
printf("这是%d位数\n",n);
}
if(n=5)
{ww=sz/10000;
qw=sz%10000/1000;
bw=sz%1000/100;
sw=sz%100/10;
gw=sz%10;
printf("%d%d%d%d%d\n",ww,qw,bw,sw,gw);
{printf("逆序打印？\n'y'是,'n'不是\n");
scanf("%c",&t);
if(t='y')printf("%d%d%d%d%d\n",gw,sw,bw,qw,ww);
else return 0;}}
else if(n=4)
{qw=sz/1000;
bw=sz%1000/100;
sw=sz%100/10;
gw=sz%10;
printf("%d%d%d%d\n",qw,bw,sw,gw);
{printf("逆序打印？\n'y'是,'n'不是\n");
scanf("%c",&t);
if(t='y')printf("%d%d%d%d%d\n",gw,sw,bw,qw);
else return 0;}}
else if(n=3)
{bw=sz/100;
sw=sz%100/10;
gw=sz%10;
printf("%d%d%d\n",bw,sw,gw);
{printf("逆序打印？\n'y'是,'n'不是\n");
scanf("%c",&t);
if(t='y')printf("%d%d%d%d\n",gw,sw,bw);
else return 0;}}
else if(n=2)
{sw=sz/10;
gw=sz%10;
printf("%d%d\n",sw,gw);
{printf("逆序打印？\n'y'是,'n'不是\n");
scanf("%c",&t);
if(t='y')printf("%d%d%d\n",gw,sw);
else return 0;}}
else
{gw=sz;
printf("%d\n",gw);
}
}

运行后出现的问题是：不管输入几位数，都打印说是2位数。但打印出的都为5位数（前面补0了）。且，不等输入t的值就打印出了逆序。

请教问题在哪，如何修改。

aitilang · #2

.......
好多重复的代码啊。。

aitilang · #3

{i=sz/10000;
if(i!=0)n=5;
else i=sz/1000;
if(i!=0)n=4;
else i=sz/100;
if(i!=0)n=3;
else i=sz/10;
if(i!=0)n=2;
else n=1; }
printf("这是%d位数\n",n);
}

这里不对，假设sz=99999，在最前面i！=0，n=5，但是后面又把n的值给改了，所以最后n会=2

robert870119 · #4

aitilang 写了：.......
好多重复的代码啊。。

是啊，我，刚学啊。。用的谭浩强的书。
现在宁愿多重复也不敢冒险啊。。慢慢会好起来吧。

robert870119 · #5

aitilang 写了：{i=sz/10000;
if(i!=0)n=5;
else i=sz/1000;
if(i!=0)n=4;
else i=sz/100;
if(i!=0)n=3;
else i=sz/10;
if(i!=0)n=2;
else n=1; }
printf("这是%d位数\n",n);
}

这里不对，假设sz=99999，在最前面i！=0，n=5，但是后面又把n的值给改了，所以最后n会=2

哦。。我想从高位排除啊，要各各if else 都加上花括号吗？

内嵌if else没搞明白看来。。

robert870119 · #6

现在改了部分代码，已经能正确判断位数了，打印出的数字也是会打印出相应的位数了，但还是有问题。

在C中，一个程序是否只允许一个scanf函数呢？现在的代码运行出来的，还是不等输入t值就按逆序打印了。

代码：全选

#include<stdio.h>
main()
{
 int sz,ww,qw,bw,sw,gw,i,n,t;
 printf("请输入不多于5位的正整数\n");
 scanf("%d",&sz);
{ if(sz/10000!=0)n=5;
 else if(sz/1000!=0)n=4;
 else if(sz/100!=0)n=3;
 else if(sz/10!=0)n=2;
 else n=1;
  printf("这是%d位数\n",n);
}
{if(n==5)
{ww=sz/10000;
qw=sz%10000/1000;
bw=sz%1000/100;
sw=sz%100/10;
gw=sz%10;
printf("%d%d%d%d%d\n",ww,qw,bw,sw,gw);
{printf("逆序打印？\n'y'是,'n'不是\n");
scanf("%c",&t);
if(t='y')printf("%d%d%d%d%d\n",gw,sw,bw,qw,ww);
else printf("不逆序打印\n");}}
else if(n==4)
{qw=sz/1000;
bw=sz%1000/100;
sw=sz%100/10;
gw=sz%10;
printf("%d%d%d%d\n",qw,bw,sw,gw);
{printf("逆序打印？\n'y'是,'n'不是\n");
scanf("%c",&t);
if(t='y')printf("%d%d%d%d\n",gw,sw,bw,qw);
else printf("不逆序打印\n");}}
else if(n==3)
{bw=sz/100;
sw=sz%100/10;
gw=sz%10;
printf("%d%d%d\n",bw,sw,gw);
{printf("逆序打印？\n'y'是,'n'不是\n");
scanf("%c",&t);
if(t='y')printf("%d%d%d\n",gw,sw,bw);
else printf("不逆序打印\n");}}
else if(n==2)
{sw=sz/10;
gw=sz%10;
printf("%d%d\n",sw,gw);
{printf("逆序打印？\n'y'是,'n'不是\n");
scanf("%c",&t);
if(t='y')printf("%d%d%d\n",gw,sw);
else printf("不逆序打印\n");}}
else {gw=sz;
printf("%d\n",gw);
}}
}

robert870119 · #7

搞定了。。。

代码：全选

#include<stdio.h>
main()
{
 int sz,ww,qw,bw,sw,gw,i,n,t;
 printf("请输入不多于5位的正整数\n");
 scanf("%d",&sz);
{ if(sz/10000!=0)n=5;
 else if(sz/1000!=0)n=4;
 else if(sz/100!=0)n=3;
 else if(sz/10!=0)n=2;
 else n=1;
  printf("这是%d位数\n",n);
}
{if(n==5)
{ww=sz/10000;
qw=sz%10000/1000;
bw=sz%1000/100;
sw=sz%100/10;
gw=sz%10;
printf("%d%d%d%d%d\n",ww,qw,bw,sw,gw);
{printf("逆序打印？\n1 是,2 不是\n");
scanf("%d",&t);
if(t==1)printf("%d%d%d%d%d\n",gw,sw,bw,qw,ww);
else printf("不逆序打印\n");}}
else if(n==4)
{qw=sz/1000;
bw=sz%1000/100;
sw=sz%100/10;
gw=sz%10;
printf("%d%d%d%d\n",qw,bw,sw,gw);
{printf("逆序打印？\n 1 是,2 不是\n");
scanf("%d",&t);
if(t==1)printf("%d%d%d%d\n",gw,sw,bw,qw);
else printf("不逆序打印\n");}}
else if(n==3)
{bw=sz/100;
sw=sz%100/10;
gw=sz%10;
printf("%d%d%d\n",bw,sw,gw);
{printf("逆序打印？\n 1 是,2 不是\n");
scanf("%d",&t);
if(t==1)printf("%d%d%d\n",gw,sw,bw);
else printf("不逆序打印\n");}}
else if(n==2)
{sw=sz/10;
gw=sz%10;
printf("%d%d\n",sw,gw);
{printf("逆序打印？\n 1 是,2 不是\n");
scanf("%d",&t);
if(t==1)printf("%d%d%d\n",gw,sw);
else printf("不逆序打印\n");}}
else {gw=sz;
printf("%d\n",gw);
}}
}

ygf · #8

我不懂C语言，这里可不可以用数组呢？好象C里也有char*类型的数组的。因为用C++的string类，这道题是非常简单的。

yxm0513 · #9

懒的看，试写了个

代码：全选

#include <stdio.h>

int check_5digit(int num){

        int n5 = num/10000;
        int n4 = (num%10000)/1000;
        int n3 = (num%1000)/100;
        int n2 = (num%100)/10;
        int n1 = num%10;
        if( n5 != 0){
                printf("The is a 5 digit num\n");
                printf("num is %d %d %d %d %d\n", n5, n4, n3, n2, n1);
                printf("backward printing is %d %d %d %d %d \n", n1, n2, n3, n4, n5);
                return 5;
        }
        else if(n4 !=0){
                printf("The is a 4 digit num\n");
                printf("num is %d %d %d %d \n", n4, n3, n2, n1);
                printf("backward printing is %d %d %d %d \n", n1, n2, n3, n4);
                return 4;
        }
        else if(n3 !=0){
                printf("The is a 3 digit num\n");
                printf("num is %d %d %d\n", n3, n2, n1);
                printf("backward printing is %d %d %d \n", n1, n2, n3);
                return 3;
        }
        else if(n2 !=0){
                printf("The is a 2 digit num\n");
                printf("num is %d %d \n", n2, n1);
                printf("backward printing is %d %d \n", n1, n2);
                return 2;
        }
        else{
                printf("The is a 1 digit num\n");
                printf("num is %d \n", n1);
                printf("backward printing is %d \n", n1);
                return 1;
        }
}

int
main(int argc, char *argv[]){
        unsigned int a;
        printf("please input a num in range (1, 100000):");
        scanf("%5d",&a);
        check_5digit(a);
        return 0;
}

newhpzzw · #10

yxm0513 写了：懒的看，试写了个

代码：全选

#include <stdio.h>

int check_5digit(int num){

        int n5 = num/10000;
        int n4 = (num%10000)/1000;
        int n3 = (num%1000)/100;
        int n2 = (num%100)/10;
        int n1 = num%10;
        if( n5 != 0){
                printf("The is a 5 digit num\n");
                printf("num is %d %d %d %d %d\n", n5, n4, n3, n2, n1);
                printf("backward printing is %d %d %d %d %d \n", n1, n2, n3, n4, n5);
                return 5;
        }
        else if(n4 !=0){
                printf("The is a 4 digit num\n");
                printf("num is %d %d %d %d \n", n4, n3, n2, n1);
                printf("backward printing is %d %d %d %d \n", n1, n2, n3, n4);
                return 4;
        }
        else if(n3 !=0){
                printf("The is a 3 digit num\n");
                printf("num is %d %d %d\n", n3, n2, n1);
                printf("backward printing is %d %d %d \n", n1, n2, n3);
                return 3;
        }
        else if(n2 !=0){
                printf("The is a 2 digit num\n");
                printf("num is %d %d \n", n2, n1);
                printf("backward printing is %d %d \n", n1, n2);
                return 2;
        }
        else{
                printf("The is a 1 digit num\n");
                printf("num is %d \n", n1);
                printf("backward printing is %d \n", n1);
                return 1;
        }
}

int
main(int argc, char *argv[]){
        unsigned int a;
        printf("please input a num in range (1, 100000):");
        scanf("%5d",&a);
        check_5digit(a);
        return 0;
}

这么多的if、else
为什么不用switch.....case来控制呢？？

liway · #11

试一下这个

代码：全选

#include <stdio.h>

int main(int argc, char *argv[])
{
	int a,i,n;
	int b[10]; 
	printf("请输入不多于5位的正整数\n");
	scanf("%d",&a);
	for(i = 0;a != 0;i++) {
		b[i] = a % 10;
		a /= 10;
	};
	printf("这是个%d位数\n",i);
	n = i;
	printf("顺序:");
	for(i = n - 1;i >= 0;i--) printf("%d ",b[i]);
	printf("\n");
	printf("逆序:");
	for(i = 0;i < n;i++) printf("%d ",b[i]);
	printf("\n");
	return 0;

}