C语言基础练习3

1.输入一行字符，分别统计出其中英文字母、空格、数字和其它字符的个数

#include<stdio.h>  #include<string.h> int main(){int letter = 0, space = 0, number = 0, other = 0, i;char ch[100];gets_s(ch);for (i = 0;i<strlen(ch); i++){if (ch[i] >= 'A'&&ch[i] <= 'Z' || ch[i] >= 'a'&&ch[i] <= 'z')letter++;else if (ch[i] == ' ')space++;else if (ch[i] <= '9'&&ch[i] >= '0')number++;elseother++;}printf("letter=%d\nspace=%d\nnumber=%d\nother=%d\n", letter, space, number, other);}

2.求Σ(k=1~100)k+Σ(k=1~50)k^2+Σ(k=1~10)1/k

#include<stdio.h>int main(){int k,a=0,b=0,c=0;for (k = 1; k <= 100; k++)a = a + k;for (k = 1; k <= 50; k++)b = b + k*k;for (k = 1; k <= 10;k++)c = c + 1 / k;printf("%d\n", a + b + c);    return 0;}

3.输出所有的“水仙花”数

#include<stdio.h>int main(){int n,i,j,k;for (n = 100; n <= 999; n++){i = n / 100;j = (n - i * 100) / 10;k = n % 10;if (n == i*i*i + j*j*j + k*k*k)printf("%d ", n);}printf("\n");    return 0;}