⑴星花#include<stdio.h>voidprintstar(intn){inti;for(i=1;i<=n;i++)printf("*");printf("\n");return;}voidmain(){inti;for(i=1;i<=10;i++)printstar(2*i-1);for(i=11;i>=1;i--)printstar(2*i-1);}⑵#include<stdio.h>floatsum(floatx,floaty){floatz;z=x+y;returnz;}voidmain(){printf("%f\n",sum(285,16.7));}⑶阶乘#include<stdio.h>longfact(intn){inti;longz=1;for(i=2;i<=n;i++)z=z*i;returnz;}voidmain(){longx;x=fact(10);printf("%ld\n",x);}⑷#include<stdio.h>floatftoc(floattemp){floatc;intf;c=(temp-32)*(5.0/9.0);returnc;}voidmain(){floatx;x=ftoc(41.0);printf("%f\n",x);}⑸#include<stdio.h>voidmain(){floatadd(floatx,floaty);floata,b,c;scanf("%f,%f",&a,&b);c=add(a,b);printf("sumis%f\n",c);}floatadd(floatx,floaty){floatz;z=x+y;return(z);}最后输入数时要用逗号隔开，跟后面的形式一样。⑹求200-300之间的素数#include<stdio.h>#include<math.h>intisprime(inta){inti;for(i=2;i<=sqrt((double)a);i++)if(a%i==0)return0;return1;}voidmain(){intx;for(x=200;x<=300;x++)if(isprime(x)==1)printf("%4d",x);}⑺将两个数进行交换#include<stdio.h>voidswap(inta,intb);voidmain(){intx=7,y=11;printf("beforeswapped:");printf("x=%d,y=%d\n",x,y);swap(7,11);printf("afterswapped:");printf("x=%d,y=%d\n",y,x);}voidswap(inta,intb){inttemp;temp=a;a=b;b=temp;}⑻通过调用swap函数，将主函数中的变量x和y中的数据进行交换。#include<stdio.h>voidswap(int,int);/*说明语句要有分号*/main(){intx=10,y=20;printf("(1)x=%dy=%d\n",x,y);swap(x,y);/*实参*/printf("(4)x=%dy=%d\n",x,y);}voidswap(inta,intb)/*形参*/实参传递给形参,x传给a,y传给b.{intt;printf("(2)a=%db=%d\n",a,b);t=a,a=b,b=t;printf("(3)a=%db=%d\n",a,b);}⑼利用递归法求n!#include<stdio.h>longfactn(intn){longL;if(n==1)return(1);L=n*factn(n-1);return(L);}voidmain(){longintL;L=factn(4);printf("%ld",L);}⑽将两个字符串合成一个#include<stdio.h>voidmergestr(chars1[],chars2[],chars3[]);voidmain(){charstr1[]={"Hello"};charstr2[]={"china!"};charstr3[40];mergestr(str1,str2,str3);printf("%s\n",str3);}voidmergestr(chars1[]