编写程序求1! 2! …… 20!。具体要求:设计一个求n!的函数,设计一个求和的函数

#include <stdio.h>

double fact(int n)

{

  if(n<2)

      return 1

  return n*fact(n-1)

}

double sigama(int a,int b,double (*f)(int))

{

  if(a>b)

      return 0

  return f(a)+sigama(a+1,b,*f)

}

int main()

{

  printf("%lf\n",sigama(1,20,fact))

  return 0

}

三种方法在同一程序里。

#include <stdio.h>

int main()

{

int i,sum=0,sum1=0,sum2=0

for (i=1i<=100i++){

sum=sum+i

if (i%2==1) sum1=sum1+ielse sum2=sum2+i

}

printf("sum=%d odd=%d ev=%d\n",sum, sum1,sum2)

i=0sum=0,sum1=0,sum2=0

do{ i++sum=sum+iif (i%2==0) sum2=sum2+i

} while (i<100)

printf("sum=%d odd=%d ev=%d\n",sum, sum-sum2,sum2)

i=0sum=0,sum1=0,sum2=0

for (i=1i<=100i=i+2) sum1=sum1+i

for (i=2i<=100i=i+2) sum2=sum2+i

sum=sum1+sum2

printf("sum=%d odd=%d ev=%d\n",sum, sum-sum2,sum2)

return 0

}

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