C语言的经典习题及程序答案.docx

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1、1.输入一个正整数求出它是几位数；输出原数和位数。#includeintdigit;voidmain(){voidcount(char[]);chartext[80];printf("Pleaseｉｎｐｕｔnumbers:");gets(text);printf("Numbers:");puts(text);digit=0;count(text);printf("digit:%d",digit);}voidcount(charstr[]){inti;for(i=0;str[i]!='';i++)if(str[i]>='0'&&str[i]<='

2、9')digit++;}2.输入一个正整数，输出原数并逆序打印出各位数字。#includevoidinvertLongInt(long);voidmain(){unsignedlongiNumber;printf("Pleaseｉｎｐｕｔanumber:");scanf("%ld",&iNumber);printf("Theｉｎｐｕｔnumberis:%ld",iNumber);printf("Theinversenumberis:");invertLongInt(iNumber);}voidinvertLongInt(longx){if(x>=0&&

3、x<=9)printf("%d",x);else{printf("%d",x%10);invertLongInt(x/10);}}3.求1!+2!+3!+……+20!，将结果输出。#includevoidmain(){floats=0,t=1;intn;for(n=1;n<=20;n++){t=t*n;s=s+t;}printf("1!+2!+3!+……+20!=%e",s);}4.打印以下图案：****************#includevoidmain(){inti,j;printf("Thepictureis:");st

4、aticcharpicture[4][7]={{'','','','*'},{'','','*','*','*'},{'','*','*','*','*','*'},{'*','*','*','*','*','*','*'}};for(i=0;i<=3;i++){for(j=0;j<=6;j++)printf("%c",picture[i][j]);printf("");}}5.打印以下图案：**********#includevoidmain(){inti,j;printf("Thepictureis:");charpicture[4][4]={{'

5、*'},{'*','*'},{'*','*','*'},{'*','*','*','*'}};for(i=0;i<=3;i++){for(j=0;j<=3;j++)printf("%c",picture[i][j]);printf("");}}6.求下列试子的值：1-1/2+1/3-1/4+……+1/99-1/100，将结果输出。#includevoidmain(){floatsum=1.0,t,s=1;inti;for(i=1;i<=100;i++){t=s/i;sum=sum+t;s=-s;}printf("1-1/2+1/3-1/4+……+1/99-

6、1/100=%5.4f",sum);}7.打印出100～999之间的所有水仙花数。#includevoidmain(){inti,j,k,n;printf("100～999之间的所有水仙花数are:");for(n=100;n<1000;n++){i=n/100;j=n/10-i*10;k=n%10;if(n==i*i*i+j*j*j+k*k*k)printf("%d",n);}printf("");}8.求Sn=a+aa+aaa+…+aa…a之值，n,a由键盘输入。#includevoidmain(){inta,n,i=1,sn

7、=0,tn=0;printf("a,n=:");scanf("%d,%d",&a,&n);while(i<=n){tn=tn+a;sn=sn+tn;a=a*10;++i;}printf("a+aa+aaa+…+aa…a=%d",sn);}9.打印以下图案：****************************#includevoidmain(){chara[7]={'*','*','*','*','*','*','*'};inti,j,k;charspace='';p