Chapter5

//例5.4 #include<stdio.h>#define MAXNUM 100000int main(){float sum,amount,ave;sum = 0;int i;for(i = 1;i<=1000;i++) {printf("请输入第%d位同学的捐款数额：",i);scanf ("%f",&amount);sum += amount;if (sum>MAXNUM)break;}ave = sum/i;printf("捐款人数%d\n平均金额%f",i,ave);return 0; } //例5.5输出100-200之间不能被3整除的数#include<stdio.h>int main(){int i;for (i = 100;i<=200;i++)//1 //if (i%3 != 0)//printf("%d\n",i);//2{if (i%3 == 0)continue;  //如果可以被3整除，在这里跳出循环 ，不执行下一步的打印操作 printf("%d\n",i);}return 0; } //例5.6输出4*5的矩阵#include<stdio.h>int main(){int i,j,k;for(i = 1;i<=4;i++)for(j = 1,k = 1;j<=5;j++,k++){printf("%d\t",i*j);if (k%5 == 0)printf("\n");}return 0; }  //break结束整个循环，continue结束当前执行的循环 //例5.7#include<stdio.h>#include<math.h> int main(){int sign;float i,sum,temp;sum = 0,i = 1,temp = 1,sign = 1;while (fabs(temp)>=1e-6){sum += temp;i += 2;sign *= -1;temp = sign/i;}printf("%f",sum*4.0);return 0; } //例5.8 斐波那契数列#include<stdio.h>int main(){int a,b,t,i;a = 1,b = 1;printf("%d\n%d\n",a,b);for (i = 2;i<=40;i++){t = a + b;printf("%d\n",t);a = b;b = t;}return 0; } //例5.8改进#include<stdio.h>int main(){int f1 = 1,f2 = 1;int i;for (i = 1;i<=20;i++){printf("%12d%12d",f1,f2);if(i%2 == 0)printf ("\n");f1 = f1 + f2;f2 = f1 + f2;}return 0; } //例5.9输入一个大于3的整数n,判断它是否为素数#include<stdio.h>int main(){int i,num,FLAG;FLAG=0;printf("请输入一个大于3的整数：");scanf("%d",&num);for (i = 2;i<num;i++)if (num % i == 0)FLAG = 1;if (FLAG == 1)printf("%d不是素数",num);elseprintf("%d是素数",num);return 0; } //不必判断num被2-（num-1）之间的数整除，只需判断（2-1/2*num或者2-sqrt(num)之间的数即可）//例5.10 100-200之间的素数#include<stdio.h>#include<math.h>int main(){int i,j,FLAG;FLAG = 0;for (i = 101;i<200;i+=2){FLAG = 0;for (j = 2;j<=sqrt(i);j++)if(i%j == 0)FLAG = 1; if (FLAG == 0)printf("%d\n",i);}return 0; } //!只对奇数进行检查 //例5.11译密码,从键盘输入一行字符，要求输出其相应的密码 #include<stdio.h> int main() { char s;  while ((s = getchar() ) != '\n') {if ((s>='a'&&s<='v')||(s>='A'&&s<='V')) s += 4;else if ((s>='w'&&s<='z')||(s>='W'&&s<='Z'))s -= 22;printf("%c",s);}return 0;  }     //5.3 输入两个正整数m和n，求其最大公约数和最小公倍数 #include<stdio.h> int main() { int m,n,t; printf("请输入两个正整数:");scanf("%d %d",&m,&n);if (m>n){t = m;m = n;n = t;}//最大公约数for(t = m;t>=0;t--){if ((m%t==0)&&(n%t==0)){printf("最大公约数%d",t);break;}} //最小公倍数for(t = n;t<=m*n;t++){if ((t%m==0)&&(t%n==0)){printf("最小公倍数%d",t);break;} }   return 0;  } //5.4 输入一行字符，分别统计出其中英文字母，空格，数字和其他字符的个数#include<stdio.h>int main(){char ch;int num_char,num_tab,num_num,num_others;num_char = 0,num_tab = 0,num_num = 0,num_others = 0;while ((ch = getchar()) != '\n'){if (((ch>='a')&&(ch<='z'))||((ch>='A')&&(ch<='Z'))) num_char++;else if (ch==' ')num_tab++;else if (ch>='0'&&ch<='9')num_num++;else num_others++;}printf("英文字母数量：%d\n空格数量：%d\n数字数量:%d\n其他字符数量:%d\n",num_char,num_tab,num_num,num_others);return 0; } //5.5求n个a的和,a是一个数字，n表示a的位数#include<stdio.h>int main(){int i,a,n,sum,temp;sum = 0,temp = 0;printf("请输入数字、位数并以空格隔开\n");scanf("%d %d",&a,&n);for(i = 1;i <= n;i++){temp =  temp * 10 + a;sum += temp;}printf("和为%d",sum);return 0;  } //5.6求阶乘之和#include<stdio.h>int main(){int i,sum,temp;sum = 0,temp = 1;for (i = 1;i<=20;i++){temp = temp*i;sum += temp;}printf("和为%d",sum);return 0; }  //5.7     ???#include<stdio.h>int main(){int i;float sum;sum = 0;for(i=1;i<=100;i++){sum += i;while (i>50)//continue;break;printf("%d\n",i);sum += i*i;while(i>10)//continue;break;printf("hello1\n");sum += 1.0/i;}printf("和为%f",sum);return 0; } //5.8水仙花数#include<stdio.h>int main(){int i;for (i = 100;i<=999;i++){if (i ==  (i/100)*(i/100)*(i/100)+ (i/10%10)*(i/10%10)*(i/10%10) + (i%10)*(i%10)*(i%10) )printf("%d\n",i);}return 0; }   //5.9完数 #include<stdio.h>int main(){int i,j,factor,sum;for (i = 1;i <= 1000;i++){sum = 0;for(j = 1;j < i ;j++){if (i % j == 0)sum += j;}if (i == sum){printf("%6dfactors are:",i);for(j = 1;j < i ;j++){if (i % j == 0)printf("%6d",j);}printf("\n");}    }    return 0; }   //5.10 求分数数列的前20项之和#include<stdio.h>int main(){int i,t;float a,b,sum;sum = 0,a = 1, b = 2;;for (i = 1;i<=20;i++){sum += b/a;    //分母为a,分子为bt = b;b = a + b;a = t;}printf("%f",sum); }  //5.11 一个球从100高度自由落下，每次落地后反跳为原高度的一半，再落下，//再反弹，求它在第10次落地时，共经过多少米，第10次反弹多高 #include<stdio.h>int main(){int i;float sum,temp;sum = 0,temp = 100;for(i = 1;i<=10;i++){sum += temp * 2;temp /= 2.0;}printf("总高度%f\n第十次%f\n",sum,temp);return 0;}//5.12猴子吃桃问题 #include<stdio.h>int main(){int day,peach_num;peach_num = 1;for(day = 9;day>0;day--)peach_num = (peach_num+1)*2;printf("%d",peach_num); } //5.13 用迭代法求x=根号下a。#include<stdio.h>#include<math.h>int main(){float x1,x2,a;x2 = 1.0;printf("请输入a的值：");scanf("%f",&a); do{x1 = x2;x2 = (x1+a/x1)/2; }while(fabs(x2-x1)>=0.000001) ;printf("%f",x2); } //5.14牛顿迭代法求下面方程在1.5附近的根#include<stdio.h>int main(){float f,f1,x0,d;x0 = 1.5;do{f = 2*x0*x0*x0 - 4*x0*x0 + 3*x0 -6;f1 = 6*x0*x0 -8*x0 + 3;d = f/f1;x0 = x0-d;}while (d>0.00001);printf("%f",x0);return 0;}//5.15用二分法求下面方程在（-10,10）之间的根：#include<stdio.h>#include<math.h>int main(){float a,b,c,fa,fb,fc;a = 10,b = -10;do{c = (a + b)/2;fc = 2*c*c*c -4*c*c +3*c -6 ;fa = 2*a*a*a -4*a*a +3*a -6 ;fb = 2*b*b*b -4*b*b +3*b -6 ;//printf("%f",fc);if (fc == 0){ //printf("根为%f\n",c);break; } if (fa*fc<0)b = c;if (fb*fc<0)a = c;}while (fabs(fc)>1e-10);printf("根为%f",c);return 0; }