小数点后位置浮点值。

Writing if statement to identify if float variable holds value behind decimal place.

写入if语句，以确定浮动变量是否具有小数点后的值。

Example code:

示例代码:

AAA = 123.456

if( AAA has value behind decimal = true)

{

        printf("true")

}

// ...or user input changes value of AAA...

AAA = 123.000


if( AAA has value behind decimal = true)

{

        printf("false")

}

Any help?

任何帮助吗?

3 个解决方案

#1

#include <stdio.h>
#include <math.h>

int main(void)
{
    double param, fractpart, intpart;

    param = 123.456;
    fractpart = modf(param , &intpart);
    if (fractpart != 0.0) {
        printf("true\n");
    } else {
        printf("false\n");
    }
    return 0;
}

Note that numerical errors arise during computations due to round-off errors and truncation, e.g.:

注意，由于舍入误差和截断，在计算过程中出现了数值误差。

0.11 - (0.07 + 0.04) != 0.0

You can control those round-off errors (adjust the EPSILON value according your scale):

您可以控制这些舍入错误(根据您的比例调整EPSILON的值):

#include <stdio.h>
#include <math.h>

#define EPSILON 0.00000000001

int almost_zero(double x)
{
    return fabs(x) < EPSILON;
}

int main(void)
{

    double param, fractpart, intpart;

    param = 0.11 - (0.07 + 0.04);
    fractpart = modf(param , &intpart);
    if (!almost_zero(fractpart)) {
        printf("true\n");
    } else {
        printf("false\n");
    }
    return 0;
}

#2

You're looking for fmod(AAA,1.0f)

你正在寻找作用(AAA,1.0度)

#3

If it fits in a long: if ((long) AAA == AAA) ...

如果它适合长时间:If ((long) AAA == AAA)……

#1

#include <stdio.h>
#include <math.h>

int main(void)
{
    double param, fractpart, intpart;

    param = 123.456;
    fractpart = modf(param , &intpart);
    if (fractpart != 0.0) {
        printf("true\n");
    } else {
        printf("false\n");
    }
    return 0;
}