[已解决]新人求助，关于c语言的简单问题

秋灯烬

我是刚学的新人，写了一个代码，但是遇到了问题。
#include<stdio.h>
int main()
{
        float floating_point;

        printf("Enter a floating-point value:______\b\b\b\b\b\b ");
        scanf_s("%f",&floating_point);
        printf("\nfixed-point notation: %f \n", floating_point);
        printf("exponential notation: %e\n", floating_point);
        printf("p notation: %a\n", floating_point);
        printf("%.2f", floating_point);

        return 0;
}


随便定义了一个变量后，输入一个数值然后输出各种格式看看，就我粗浅的学识，认为double要比float范围大一些，不考虑什么字节大小之类的情况。

把float---->变成double应该没什么事

但是当我变了以后

Enter a floating-point value: 64.25

fixed-point notation: 64.250000
exponential notation: 6.425000e+01
p notation: 0x1.0100000000000p+6
64.25

也变成了

Enter a floating-point value: 64.25

fixed-point notation: -92559604856675321571320088795986877361484249085968211295338496.000000
exponential notation: -9.255960e+61
p notation: -0x1.ccccc42808000p+205
-92559604856675321571320088795986877361484249085968211295338496.00
就很疑惑，有大佬知道为什么吗

最佳答案

月排行榜 / 总排行榜

大马强

2022-2-20 16:56:53

因为double数据格式化输入要用%lf

Enter a floating-point value: 64.25

fixed-point notation: 64.250000
exponential notation: 6.425000e+001
p notation: 0x1.010000p+6
64.25
--------------------------------
Process exited after 31.32 seconds with return value 0
请按任意键继续. . .

#include<stdio.h>
int main()
{
        double floating_point;

        printf("Enter a floating-point value:______\b\b\b\b\b\b ");
        scanf_s("%lf",&floating_point);                             // 要用%lf 
        printf("\nfixed-point notation: %f \n", floating_point);
        printf("exponential notation: %e\n", floating_point);
        printf("p notation: %a\n", floating_point);
        printf("%.2f", floating_point);

        return 0;
}

跳转到最佳答案楼层

大马强

因为double数据格式化输入要用%lf

Enter a floating-point value: 64.25

fixed-point notation: 64.250000
exponential notation: 6.425000e+001
p notation: 0x1.010000p+6
64.25
--------------------------------
Process exited after 31.32 seconds with return value 0
请按任意键继续. . .

#include<stdio.h>
int main()
{
        double floating_point;

        printf("Enter a floating-point value:______\b\b\b\b\b\b ");
        scanf_s("%lf",&floating_point);                             // 要用%lf 
        printf("\nfixed-point notation: %f \n", floating_point);
        printf("exponential notation: %e\n", floating_point);
        printf("p notation: %a\n", floating_point);
        printf("%.2f", floating_point);

        return 0;
}

ckblt

把 scanf_s("%f",&floating_point);
改成 scanf_s("%lf",&floating_point);

秋灯烬

ckblt 发表于 2022-2-20 16:57
把 scanf_s("%f",&floating_point);
改成 scanf_s("%lf",&floating_point);

感谢大佬解答

秋灯烬

大马强 发表于 2022-2-20 16:56
因为double数据格式化输入要用%lf

感谢大佬解答