以下程式都是在VS軟體下進行編譯的，如果要用VC編譯器，刪除system(“paues”);即可
9.1

//No.1不用遞迴
#include<stdio.h>
#define N 20
void selection_sort(int k, int c[]);
int main(int argc,char *argv[])
{
	int a[N];
	int n;
	printf("Enter total of numbers:");
	scanf("%d", &n);
	printf("Enter numbers:");
	int i;
	for (i = 0; i < n; i++)
	{
		scanf("%d", &a[i]);
	}

	selection_sort(n, a);
	for (i = 0; i < n; i++)
	{
		printf("%d ", a[i]);
	}
	puts("");
	system("pause");
	return 0;
}
void selection_sort(int m, int b[])
{
	int j, i;
	int tmp;;
	for (j = 0; j < m; j++)
	{
		for (i = j+1; i < m; i++)
		{
			if (b[j] >= b[i])
			{
				tmp = b[j];
				b[j] = b[i];
				b[i] = tmp;
			}
		}
	}
}
 

//No.1遞迴方法

#include<stdio.h>
#define N 20

void sort(int a,int p[]);
int main()
{
	int num[N];
	int i,n;
	printf("Enter total of numbers:");
	scanf("%d",&n);
	printf("Enter numbers:");
	for(i=0;i<n;i++)
	{
		scanf("%d",&num[i]);
	}
	printf("The sort number is:");
	sort(n,num);
	for(i=0;i<n;i++)
	{
		printf("%d ",num[i]);
	}
	puts("");
	return 0;
}
void sort(int a,int p[])
{
	int i;
	int m=p[0];
	int j=0;
	for(i=0;i<a;i++)
	{
		if(m<=p[i])
		{
			m=p[i];
			j=i;
		}
	}
	p[j]=p[a-1];
	p[a-1]=m;

	if(a==0)return;
	sort(a-1,p);
}
 

9.2

#include<stdio.h>

float Taxes(float n);
int main(int argc, char *argv[])
{
	float taxes;
	float income;

	printf("Enter incomes:");
	scanf("%f", &income);
	taxes = Taxes(income);
	printf("The taxes is:%.2f\n", taxes);
	system("pause");
	return 0;
}

float Taxes(float n)
{

	if (n <= 750)return n*0.01;
	else if (n <= 2250)return 7.5f + (n - 750)*0.02;
	else if (n <= 3750)return 37.5f + (n - 2250)*0.03;
	else if (n <= 5250)return 82.5f + (n - 3750)*0.04;
	else if (n <= 7000)return 142.5f + (n - 5250)*0.05;
	else 
	{
		return 230.0f + (n - 7000)*0.06;
	}
	
}