格式说明符％Lf为`long double`变量给出错误 [英] Format specifier %Lf is giving errors for `long double` variables

问题描述

我遇到以下错误:

In function 'main':
[Warning] unknown conversion type character 'L' in format [-Wformat=]
[Warning] too many arguments for format [-Wformat-extra-args]

In function 'error_user':
[Warning] unknown conversion type character 'L' in format [-Wformat=]
[Warning] too many arguments for format [-Wformat-extra-args]

在下面的代码中:

#include <stdio.h>
#include <stdlib.h>

void error_user (long double *error);

int main(void)
{
    long double error;

    printf("What error do you want?\n");

    error_user (&error);

    printf("%Lf\n", error);

    return 0;
}

void error_user (long double *error)
{
    scanf("%Lf", error);
}

据我所知，long double的格式说明符为%Lf，因此不确定如何解决该问题.谢谢！

As far as I know the format specifier of a long double is %Lf so not really sure how to solve this one. Thank you!

在 DEV-C ++ 中与TDM-GCC 4.9.2 64-bit Release一起编译.

推荐答案

您的编译器无法识别%Lf，您需要提供编译器标志-D__USE_MINGW_ANSI_STDIO=1

Your compiler doesn't recognize %Lf , you need to provide the compiler flag -D__USE_MINGW_ANSI_STDIO=1

示例:

$ gcc filename.c -Wall -Wextra -pedantic -O3 -D__USE_MINGW_ANSI_STDIO=1
                                             ^^^^^^^^^^^^^^^^^^^^^^^^^^

在使用Dev-C++时，您可能还应该添加-std=c11标志以启用C11标准.

As you are using Dev-C++, you should probably also add -std=c11 flag to enable C11 standard.

此线程说明了应如何将标志添加到Dev-C++:

This thread explains how you should add flags to Dev-C++:

如何将模式从Dev-C ++中的c ++ 98模式更改为支持C ++ 0x的模式(基于)?

因此，您需要使用链接线程中的指令添加标志-std=c11和-D__USE_MINGW_ANSI_STDIO=1.

So you need to add the flags -std=c11 and -D__USE_MINGW_ANSI_STDIO=1 using the instructions in the linked thread.

由于Dev-C ++使用的是较旧的标准，因此仅添加-std=c11即可解决此问题.先尝试一下.

Since Dev-C++ uses an older standard, it's possible that adding only -std=c11 can solve the issue. Try it first.

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