走出一小步

//1，打印100到200之间的素数#define _CRT_SECURE_NO_WARNINGS 1#include <stdio.h>#include <math.h>int main(){int i = 0, j = 0,count=0;printf("100到200之间的素数有：\n");for (i = 101; i <= 200; i+=2){int k = (int)(sqrt)(i*1.0);//经证明只需验证到算数平方根即可for (j = 2; j <= k; j++){if (i%j == 0) { break; }}if (j == k + 1){printf("%6d", i);count=count+1;if (count % 5 == 0){printf("\n");}}}printf("\n");printf("100到200之间的素数有%d个",count);getchar();return 0;}//2，输出乘法口诀#define _CRT_SECURE_NO_WARNINGS 1#include <stdio.h>int main(){int i = 0, j = 0, m = 0;printf("输出乘法口诀如下\n");for (i = 1; i <= 9; i++){for (j = 1; j <= i; j++){m = i*j;printf("%d * %d = %d  ", i, j, m);}printf("\n")}getchar();return 0;}//3.判断1000年到2000年之间的闰年#define _CRT_SECURE_NO_WARNINGS 1#include <stdio.h>int main(){int  i = 0, year1 = 1000, year2 = 2000;printf("输出1000年到2000年之间的闰年：");for (i = year1; i <= year2; i++){if (((i % 4 == 0) && (i % 100 != 0)) || (i % 400 == 0))//闰年的要求是，被4整除但不能被100整除，或者可以直接被400整除{printf("%7d", i);}}getchar();return 0;}