task1-1

#include <stdio.h>
long long fac(int n);
int main()
{
	int i, n;
	printf("Enter n: ");
	scanf("%d", &n);
	for (i = 1; i <= n; ++i)
	printf("%d! = %lld\n", i, fac(i));
	return 0;
}
long long fac(int n)
	{
	static long long p = 1;
	p = p * n;
	return p;
}

 

 task1-2

#include <stdio.h>
int func(int, int);
int main()
{
	int k = 4, m = 1, p1, p2;
	p1 = func(k, m); 
	p2 = func(k, m); 
	printf("%d,%d\n", p1, p2);
	return 0;
}

int func(int a, int b)
{
	static int m = 0, i = 2;
	i += m + 1;
	m = i + a + b;
	return (m);
}

 

task2-1

#include <stdio.h>
void printSymbol(int n, char symbol);
int main()
{
	int n;
	char symbol;
	while( scanf("%d %c", &n, &symbol) != EOF )
	{
	printSymbol(n, symbol);
	printf("\n");
	}
	return 0;
}
void printSymbol(int n,char symbol)
{
	while(n--)
	printf("%c",symbol);
}

 

 task 2-2

#include <stdio.h>
void printSymbol(int n, char symbol);
int main()
{
	int n;
	char symbol;
	while( scanf("%d %c", &n, &symbol) != EOF )
	{
	printSymbol(n, symbol);
	printf("\n");
	}
	return 0;
}
void printSymbol(int n,char symbol)
{
	if(n>0)
	{
		printf("%c",symbol);
		n--;
		printSymbol(n,symbol);
	}	
}

 

task 3

#include <stdio.h>
long long fun(int n);
int m;
int main()
{
	int n;
	long long f;
	while (scanf("%d", &n) != EOF)
	{
	m=1;
	f = fun(n);
	printf("n = %d, f = %lld\n", n, f);
	}
	return 0;
}
long long fun(int n)
{
	if(n>0)
	{
		m*=2;
		n--;
		fun(n);
	}
	else
	return m-1;
}

 

task 4

#include<stdio.h>
#include<math.h>
int isPrime(int n);
int main()
{
	int t=0;
	for(int i=101;i<=200;i++)
	{
		if(!isPrime(i))
		{
			t++;
			printf("%d ",i);
		}
	}
	printf("\n101~200之间一共有%d个非素数",t);
	return 0;
}
int isPrime(int n)
{
	int s=0;
	for(int j=2;j<=sqrt(n);j++)
	{
		if(n%j==0) s++;
	}
	if(s==0) return 1;
	else return 0;
}

 

 task 5

#include <stdio.h>
#include<math.h>
long fun(long s);
int main()
{
	long s,t;
	printf("Enter a number: ");
	while(scanf("%ld",&s)!=EOF)
	{
	t=fun(s);
	printf("new number is: %ld\n\n",t);
	printf("Enter a number: ");
	}
	return 0;
}
long fun(long s)
{
	long m=0,n,p=0,j=0,s0;//m存储数值的位数 n存奇数数字 p存新数字
	s0=s;//备份s的值 
	do
	{
		m++; 
		s=s/10;
	}while(s!=0);
	for(long i=0;i<m;i++)
	{
		if(s0/(long)pow(10,i)%2!=0) //判断是奇数
		{
		n=s0/(long)pow(10,i)%10;
		p+=n*pow(10,j);
		j++;
		}
	}
	return p;
}

 task 6

#include <stdio.h>
double fun(int n);
int main()
{
	int n;
	double s;
	printf("Enter n(1~10): ");
	while(scanf("%d",&n)!=EOF)
	{
		s=fun(n); 
		printf("n=%d,s=%f\n\n",n,s);
		printf("Enter n(1~10): ");
	}
	return 0;
}
double fun(int n)
{
	double mom=1,son=1,sum=0;
	for(double i=1;i<=n;i++)
	{
		mom=1;//考虑到mom会变化，所以每次循环进行一次初始化 
		for(double j=1;j<=i;j++) mom*=j;
		sum+=son/mom;
		son=-son;
	}
	return sum;
}