1. 題目：寫一個程式，判斷兩個浮點數是否足夠精確。

/*  File name:ApproximatelyEqual
	Function: ensure the accurcy of two numbers.|x-y|/min(|x|,|y|)<e 
	Time: 2018.04.07
	edited by QJX	
*/

#include <stdio.h>
#include <math.h>
double Minfabsnum(double x,double y);	//Calculate the min of fabs(x),fabs(y)
void GiveInstruction(void);	//Give instruction and reference to users
#define e 0.0001	//The accurcy 

double main()
{
	 double x,y,c;
	 GiveInstruction();
	 printf("Please input 2 numers:");
	 scanf("%lf,%lf",&x,&y);
	 c=Minfabsnum(x,y);
	 if(fabs(x-y)/c<e)
	 	printf("Two numers satisfy the accurcy!");
	else 
		printf("Two numers not satisfy the accurcy!");
} 

double Minfabsnum(double x,double y)	//Calculate the min of fabs(x),fabs(y)
{
	double a,b;
	a=fabs(x);
	b=fabs(y);
	if(a<=b)
	return a;
	else
	return b;
}

void GiveInstruction(void)	//Give instruction and reference to users
{
	printf("This program can ensure the accurcy of two double numbers!\n");
	printf("And the accurcy is 0.0001\n\n");
}
 

2. 題目：列印楊輝三角前八行

/*  File name:Pascal triangle or YangHui triangle
	Founction: display the 8 raws of YangHui triangle
	Time:2018.04.07
	edited by qjx
*/

#include <stdio.h>
#define N 8
int Factorial(int n);
int Combinations(int n,int k);
void GiveInstruction(void);

main()
{
	int raw,i,j,k;
	GiveInstruction();
	printf("Please input the raws of YangHui triangle:");
	scanf("%d",&raw);
	for(i=1;i<=raw;i++)
	{
		for(j=0;j<raw-i;j++)	//print the spacebar
		{
			printf(" ");
		}
		for(k=0;k<=i-1;k++)	//print the YangHui triangle
		{
			printf("%4d ",Combinations(i-1,k));	
		//	printf(" ");
		}
		printf("\n");
	}
}

int Factorial(int n)   //calculate n！
{
	int i,product=1;
	for(i=1;i<=n;i++)
	{
		product*=i;
	}
	return product; 
}

int Combinations(int n,int k)    //calculate C(n,k)=n!/(k!*(n-k)!)
{
	int a,b,c;
	a=Factorial(n);
	b=Factorial(k);
	c=Factorial(n-k);
	return a/(b*c);
}

void GiveInstruction(void)
{
	printf("This program can display the YangHui triangle!\n");
	printf("For example:\n");
	printf("  1  \n");
	printf(" 1 1 \n");
	printf("1 2 1\n");
}
 

本來以為是超出了int型的範圍，但是手動計算之後並沒有超出啊，而且如果超出的話，在計算12！時，就已經超出範圍了。不解！

解決：還是int範圍的問題

#include <stdio.h> 
#include <limits.h>
#define N 13
int Factorial(int n);

main()
{
	int a;
	a=Factorial(N);
	printf("%d",a);
	printf("The value of INT_MAX is %i\n", INT_MAX);	
	printf("The value of INT_MIN is %i\n", INT_MIN);	
	printf("An int takes %d bytes\n", sizeof(int));

}

int Factorial(int n)   //calculate n！  
{  
    int i,product=1;  
    for(i=1;i<=n;i++)  
    {  
        product*=i;  
    }  
    return product;   
}  
 

採用如上程式碼，改變N的值，可以清楚地看到溢位的時刻。