《数据结构与算法分析 c语言描述》习题1.3

(编译环境 Microsoft Visual Studio 2019)

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
void PrintDigit(unsigned int n);
void printint(int n);
void printout(double n, int decimal_digit);
int decimal_digit(char* value);

int main(void)
{
	double num;
	char value[40];

	printf("N= ");
	scanf_s("%s", &value, 40);
	num = atof(value);
	printf("PrintOut: ");
	printout(num, decimal_digit(value));
	putchar('\n');

	return 0;
}

int decimal_digit(char* value)
{
	int int_digit = 0;
	int n;
	
	n = strlen(value);
	while (*value != '.' && *value != '\0')
	{
		int_digit++;
		value++;
	}
	if (*value == '.')
		return n - int_digit - 1;
	return 0;
}

void printout(double num, int decimal_digit)
{
	int i;
	int integer;
	double decimal;

	if (num < 0)
	{
		num = -num;
		putchar('-');
	}
	integer = (int)num;
	printint(integer);
	if (decimal_digit != 0)
	{
		putchar('.');
		decimal = num - integer;
		for (i = 0; i < decimal_digit; i++)
		{
			decimal *= 10;
		}
		if ((int)(decimal * 10) % 10 > 5)
			decimal += 1;
		printint((int)decimal);
	}
}

void printint(int n)
{

	if (n >= 10)
		printint(n / 10);
	PrintDigit(n - n / 10 * 10);
}

void PrintDigit(unsigned int n)
{
	printf("%d", n);
}