PTA《C语言程序设计（第四版）》第六章练习题

看别人的代码写的就没记录

习题6-2 使用函数求特殊a串数列和

int fn( int a, int n )
{
	int u = a;
	for(int i=1;i<n;i++)
	{
		u = u*10+a;
	}
	return u;
}

int SumA( int a, int n )
{
	int sum = 0;
	for(int j = 1;j<=n;j++)
	{
		sum = sum+fn(a,j);
	}
	return sum;
}

习题6-3 使用函数输出指定范围内的完数

int factorsum( int number )
{
	if(number == 1) return 0;
    int sum = 1;
	int i =2;
	while(i<number)
	{
		if(number%i==0) sum = sum+i;
		i++;
	}
	return sum;
}

void PrintPN( int m, int n )
{
	int count = 0;
	for(int i = m;i<=n;i++)
	{
		if(factorsum(i)==i)
		{
			count++;
			printf("%d = 1",i);
			int j = 2;
			while(j<i)
			{
				if(i%j==0) 
				{
					printf(" + ");
					printf("%d",j);
				}
				j++;
			}
			putchar('\n');
		}
		
	}
	if(count == 0) printf("No perfect number");
}

习题6-4 使用函数输出指定范围内的Fibonacci数

int fib( int n )
{
	int a,b,c;
	a=b=c=1;
	for(int i=3;i<=n;i++)
	{
		c = a+b;
		a = b;
		b = c;
	}
	return c;
}

void PrintFN( int m, int n )
{
	int oc = 0;
	int j = 1;
	while(fib(j)<m) j++;
	int q = 1;
	while(fib(q)<=n) q++;
    q=q-1;
	for(int i=m;i<=n;i++)
	{
		for(int k=j;fib(k)<=i;k++)
		{
			if(fib(k)==i)
			{
				oc = 1;
				printf("%d",i);
				if(k<q) printf(" ");
			}
		}
	}
	if(oc==0) printf("No Fibonacci number");
}

习题6-5 使用函数验证哥德巴赫猜想

int prime( int p )
{
	if(p == 1) return 0;
	if(p == 2) return 1;
	for(int i = 2;i<(sqrt(p)+1);i++)
	{
		if(p%i==0) return 0;
	}
	return 1;
}

void Goldbach( int n )
{
	int i = n-3;
	while(i>=3)
	{
		if(prime(i)==1)
		{
			int j = n-i;
			if(prime(j) == 1)
			{
			printf("%d=%d+%d",n,j,i);
			break;
			}
		}
		i = i-2;
	}
	
}

习题6-6 使用函数输出一个整数的逆序数

int reverse( int number )
{
	int sum, n;
	sum = n = 0;
	int a = number;
	while(a!=0)
	{
		n++;
		a = a/10;
	}
	
	while(number!=0)
	{
		int b = number%10;
		for(int i=1;i<n;i++)
		{
			b = b*10;
		}
		sum = sum+b;
		number = number/10;
		n--;
	}
	return sum;
}

习题6-7 简单计算器

#include
int main()
{
	int n,m;
	int fact = 1;
	char ch;
	scanf("%d",&n);
	ch = getchar();
	while(ch!='=')
	{
		scanf("%d",&m);
		if(ch == '+')
		{
			n = n+m;
		}else if(ch == '-')
		{
			n = n-m;
		}else if(ch == '*')
		{
			n = n*m;
		}else if(ch == '/')
		{
			if(m==0) fact = 0;
			else n = n/m;
		}else fact = 0;
		ch = getchar();
	}
	if(fact == 0) printf("ERROR");
	else printf("%d",n);
	return 0;
	
}

习题6-8 单词首字母大写

#include
int main()
{
	int i = 1;
	char ch;
	ch = getchar();
	while(ch!='\n')
	{
		if(i == 1)
		{
			if(ch>='a'&&ch<='z') ch = ch-'a'+'A';
		}
		putchar(ch);
		i++;
		if(ch == ' ') i = 1;
		ch = getchar();
		
	}
	return 0;
}