输出double类型的变量时出现问题

[TwenteMaster]

我用的编译器是MinGW 4.6.1
源程序：
/* Exercise 5.1 Get the reciprocals */
#include <stdio.h>

int main(void)
{
double values[5] = {0.0}; /* Store five doubles */
double reciprocals[5] = {0.0}; /* Store the reciprocals of the five values */
double sum = 0.0; /* Store the sum of reciprocals */

printf("Enter five doubles you want: \n");
for(int i = 0 ; i < 5 ; i++)
{
scanf("%lf" , &values[i]);
}

/* Get the reciprocals */
for(int i = 0 ; i < 5 ; i++)
{
reciprocals[i] = 1.0 / values[i];
printf("values[%d] is: %.3lf\n" , i , values[i]);
}

/* Display the sum of the reciprocals */
for(int i = 0 ; i < 5 ; i++)
{
sum += reciprocals[i];
}
printf("The sum of reciprocals is: %.3lf\n" , sum);
return 0;
}
程序运行后输出的结果全部是0.000,请问这是为什么?

[xxweilw]

你输入值的时候是不是没回车啊，输入一个回车一次

[xxweilw]

还有后面的int i没问题吗，把后边两个int i = 0变成i=0吧

[赵4老师]

printf("values[%d] is: %lg\n" , i , values[i]);
单步调试和设断点调试是程序员必须掌握的技能之一。

[無_1024]

#include <stdio.h>

int main(void)
{
	double values[5] = {0.0}; /* Store five doubles */
	double reciprocals[5] = {0.0}; /* Store the reciprocals of the five values */
	double sum = 0.0; /* Store the sum of reciprocals */
	int i = 0;
	printf("Enter five doubles you want: \n");
	for(i = 0 ; i < 5 ; i++)
	{
		scanf("%lf" , &values[i]);
	}
	
	/* Get the reciprocals */
	for( i = 0 ; i < 5 ; i++)
	{
		reciprocals[i] = 1.0 / values[i];
		printf("values[%d] is: %.3lf\n" , i , values[i]);
	}
	
	/* Display the sum of the reciprocals */
	for( i = 0 ; i < 5 ; i++)
	{
		sum += reciprocals[i];
	}
	printf("The sum of reciprocals is: %.3lf\n" , sum);
	return 0;
}
//VC6.0运行正常的

[Athenacle_]

gcc表示毫无问题。。MinGW怎么就出错了呢？

wangxiao@Main-WangXiao ~$ ./a.out 
Enter five doubles you want: 
1.2
2.3
3.4
4.5
5.6
values[0] is: 1.200
values[1] is: 2.300
values[2] is: 3.400
values[3] is: 4.500
values[4] is: 5.600
The sum of reciprocals is: 1.963

[lost_goast]

i变量需要在每一个for（）里面都要重新定义一次吗？？

[月夜csdn]

#include <stdio.h>

int main(void)
{
double values[5] = {0.0}; /* Store five doubles */
double reciprocals[5] = {0.0}; /* Store the reciprocals of the five values */
double sum = 0.0; /* Store the sum of reciprocals */
int i;                //把后边用到的i提前声明在了这里

printf("Enter five doubles you want: \n");
for(i = 0 ; i < 5 ; i++)
{
scanf("%lf" , &values[i]);
}

/* Get the reciprocals */
for(i = 0 ; i < 5 ; i++)
{
reciprocals[i] = 1.0 / values[i];
printf("values[%d] is: %.3lf\n" , i , values[i]);
}

/* Display the sum of the reciprocals */
for(i = 0 ; i < 5 ; i++)
{
sum += reciprocals[i];
}
printf("The sum of reciprocals is: %.3lf\n" , sum);
return 0;
}

我用VC6.0试了下。应该是没问题。一切正常

[狂且]

/* Exercise 5.1 Get the reciprocals */
#include <stdio.h>

int main(void)
{
    double values[5] = {0.0}; /* Store five doubles */
    double reciprocals[5] = {0.0}; /* Store the reciprocals of the five values */
    double sum = 0.0; /* Store the sum of reciprocals */

    printf("Enter five doubles you want: \n");
    for(int i = 0 ; i < 5 ; i++)
    {
        scanf("%lf" , &values[i]);   //取值的时候用 %lf 就行.
    }

    /* Get the reciprocals */
    for(int i = 0 ; i < 5 ; i++)
    {
        reciprocals[i] = 1.0 / values[i];
        printf("values[%d] is: %.3f\n" , i , values[i]);  // 改成 %.3f 就可以了.
    }

    /* Display the sum of the reciprocals */
    for(int i = 0 ; i < 5 ; i++)
    {
        sum += reciprocals[i];
    }
    printf("The sum of reciprocals is: %.3f\n" , sum);    // 同上

    return 0;
}

/*
**********************************************************************
    我用CodeBlocks, GNU-GCC 编译的. 我也不清楚为啥获取值的时候用 %lf,
    打印的时候就用 %f. 不然也会出现你这个问题, 输出是 0. 求高手
    讲解. 另外, 没改正之前, VS2008运行你的程序没有问题. 结果正常.
**********************************************************************
*/

[狂且]

需要, 这 for() 里的 i 是局部变量. 作用域只是在 for() 内部.
到下一个 for() 就不起作用了.
[Quote=引用 6 楼 lost_goast 的回复:]

i变量需要在每一个for（）里面都要重新定义一次吗？？
[/Quote]

[TwenteMaster]

我是看到书上写的：double类型的要用%lf，我该为%f后程序就没有问题了，我也不知道这是为什么，难道书上也出错了？
[Quote=引用 8 楼 nnrroo 的回复:]

C/C++ code
/* Exercise 5.1 Get the reciprocals */
#include <stdio.h>

int main(void)
{
double values[5] = {0.0}; /* Store five doubles */
double reciprocals[5] = {0.0}; /* Store the reciproc……
[/Quote]