void main()
{int i = 0;int sum = 0;while (i <= 100) {//求1到100累加和sum = sum + i;i++;}printf("%d\n", sum);
}
void main() {int i = 0;int sum = 0;while (i <= 100) {//求1到100偶数累加和printf("%d\n", i);sum = sum + i;i += 2;}printf("%d\n", sum);
}
void main() {int i = 1;int sum = 0;while (i <= 100) {//求1到100奇数累加和printf("%d\n", i);sum = sum + i;i += 2;}printf("%d\n", sum);
}
void main()
{int i = 1;int sum = 0;int sign = 1;while (i <= 100) {//1-2+3-4+......-100printf("%u\n", i);sum = sum + sign * i;i++;sign = -sign;}printf("%d\n", sum);
}
void  main() {int i = 1;float sum = 0;while (i <= 100) {//1+1/2+1/3+....+1/100sum = sum + 1.0/i;i++;}printf("sum=%f\n", sum);
}

void main() {char i = 'A';while (i <= 'Z') {printf("%c\n", i);i++;   }
}

void main() {int n, f, i;printf("请输入n:");scanf_s("%d", &n);for (i = 1, f = 1; i <= n; i++)f = f * i;printf("%d!=%d\n", n, f);
}

void main(){int x,d;scanf_s("%d", &x);printf("%d的倒序是：", x);while (x != 0) {d = x % 10;x = x / 10;printf("%d",d);}
}

void main() {int i, j;for (i = 1; i <= 9; i++) {for (j = 1; j <= i; j++) {printf("%d*%d=%-4d", i, j, i * j);}printf("\n");}
}

void main() {int i = 0;int sum = 0;while (2) {if (i > 100)break;sum = sum + i;i++;}printf("%d", sum);
}void main() {char c;while (1) {c = getchar();if (c >= 'a' && c <= 'z')putchar(c - 32);elsebreak;}
}
void main() {char c;scanf_s("%c", &c);while (1) {if (c >= 'a' && c <= 'z') {c = c - 32;putchar(c);}elsebreak;}
}

void main() {int i;for (i = 100; i <= 200; i++) {if (i % 3 != 0)printf("%4d", i);}
}
void main() {int i;for (i = 100; i <= 200; i++) {if (i % 3 == 0)continue;printf("%4d", i);}
}

9.求Pi的值，根据

void main() {int sign = 1;double pi = 0, n = 1, term = 1;while (fabs(term) >= 1e-6) {pi = pi + term;n = n + 2;sign = -sign;term = sign / n;}pi = pi * 4;printf("%10.8f", pi);
}

void main() {int f1 = 1;int f2 = 1;int i;int k;scanf_s("%d", &k);    for (i = 1; i <= k; i++) {printf("%12ld%12ld", f1, f2);if (i % 2 == 0)printf("\n");f1 = f1 + f2;f2 = f2 + f1;}
}
void main() {int i, n, k;scanf_s("%d", &k);long a, b, next;a = b = 1;printf("%20ld%20ld", a, b);n = 2;for (i = 3; i <= k; i++) {next = a + b;printf(" % 20ld", next);n++;if (n % 4 == 0)printf("\n");a = b;b = next;}
}

void main() {int i;int n;scanf_s("%d", &n);for (i = 2; i <= n - 1; i++)if (n % i == 0)break;if (i >= n)printf("%d是素数", n);elseprintf("%d不是素数",n);
}
#include <stdio.h>
#include<math.h>
#define _CRT_SECURE_NO_WARNINGS
void main() {int i;int n;scanf_s("%d", &n);int temp = (int)(sqrt(n));for (i = 2; i <=temp; i++)if (n % i == 0)break;if (i >= temp)printf("%d是素数", n);elseprintf("%d不是素数", n);
}

void main() {int i;int n;for (n = 3; n <=99; n++){for(i=4;i<=n-1;i++)if (n % i == 0)break;if (i >= n)printf("%d是素数\n", n);}
}

void main() {int i = 0;float sum = 0;float x;for (i = 1; i <= 1000; i++) {scanf_s("%f", &x);sum = sum + x;if (sum >= M) {break;}}if (i <= 1000) {printf("%d\n%f", i, sum);}elseprintf("%d\n%f", i - 1, sum);
}

void main() {int c1 = 0, c2 = 0, c3 = 0, c4 = 0;printf("请输入一行字符:");char c;while ((c = getchar()) != '\n') {if (c >= 'a' && c <= 'z'|| c >= 'A' && c <= 'Z')c1++;else if (c >= '0' && c <= '9')c2++;else if (c == ' ')c3++;elsec4++;}printf("字母数：%d\n数字数：%d\n空格数：%d\n其他符号数：%d\n", c1, c2, c3, c4);
}

void main() {int r, m, n, t;scanf_s("%d\n%d", &m, &n);if (m < n) {t = m;m = n;n = t;}while (2) {r = m % n;if (r == 0) {printf("%d", n);break;}m = n;n = r;}
}

void main() {int n, i;float fac, sum = 0;for (n = 1; n <= 20; n++) {i = 1; fac = 1;do {fac = fac * i;i++;} while (i <= n);sum = sum + fac;}printf("sum=%e\n", sum);
}
void main() {int n;float fac = 1, sum = 0;for (n = 1; n <= 20; n++) {fac = fac * n;sum = sum + fac;}printf("sum=%e\n", sum);
}

void main() {int n;float fac = 1, sum = 0;for (n = 1; n <= 20; n++) {fac = fac * 2;sum = sum + fac;}printf("sum=%e\n", sum);
}

void main() {int x, y, z;for (x = 0; x <= 100; x++) {for (y = 0; y <= 100; y++) {z = 100 - x - y;if (15 * x + 9 * y + z==300) {printf("公鸡：%8d\t母鸡：%8d\t小鸡：%8d\n", x, y, z);}}}
}

void main() {int i;int b0, b1, b2;for (i = 100; i <= 999; i++) {b0 = i % 10;b1 = i / 10 % 10;b2 = i / 100;if (b0 * b0 * b0 + b1 * b1 * b1 + b2 * b2 * b2 == i)printf("水仙花数：%d\n", i);}
}

void main() {char c;c = getchar();while (c != '\n') {if (c >= 'a' && c <= 'z' || c >= 'A' && c <= 'Z') {if (c >= 'w' && c <= 'z' || c >= 'W' && c <= 'Z') {c = c - 22;}else c = c + 4;}printf("%c", c);}
}

void main() {int i,k,s;for (i = 1; i < 1000; i++) {s = 0;for (k = 1; k < i; k++)       if (i % k == 0)s = s + k;if (s == i)printf("%d\n", i);}
}