各位大侠您们好

           有个新问题请教，我要是用 vsprintf显示字符，为什么%d,%s都可以，而%f一直都是0.000000？
这个问题可是奇怪了，还有大侠指教下啊？谢谢

#include <string.h>
#include <math.h>
#include <stdlib.h>
#include <stdio.h>
#include <stdarg.h>


void Uart_Printf(char *pTransBuf,char *fmt,...)
{
        u8 i;
       
        va_list ap;

        va_start(ap,fmt);
        vsprintf(pTransBuf,fmt,ap);
        va_end(ap);

}

数据填入pTransBuf缓冲区，使用%f,固定就填0.000000，晕死

使用的是是stm32f207,内部存储器

唉，没有人指教？怎么我尽碰到这种稀奇古怪的问题

顶一下，怎么没有人指教啊？

怎么没用回复？都没有碰到过么？

楼主，没有碰到类似的问题，我一般使用sprintf，而且是直接调用。还是你编程的问题要多一些。ap这个值是什么类型？

我发现和stemwin 的 GUI_TOUCH_Exec(); 有关，不使用GUI_TOUCH_Exec(); 就没有问题，一循环调用
GUI_TOUCH_Exec(); 就出问题了，这个是怎么回事情？

就是使用sprintf也是一样，有指教的么？

extern _ARMABI int fprintf(FILE * __restrict /*stream*/,
                    const char * __restrict /*format*/, ...) __attribute__((__nonnull__(1,2)));
   /*
    * writes output to the stream pointed to by stream, under control of the
    * string pointed to by format that specifies how subsequent arguments are
    * converted for output. If there are insufficient arguments for the format,
    * the behaviour is undefined. If the format is exhausted while arguments
    * remain, the excess arguments are evaluated but otherwise ignored. The
    * fprintf function returns when the end of the format string is reached.
    * The format shall be a multibyte character sequence, beginning and ending
    * in its initial shift state. The format is composed of zero or more
    * directives: ordinary multibyte characters (not %), which are copied
    * unchanged to the output stream; and conversion specifiers, each of which
    * results in fetching zero or more subsequent arguments. Each conversion
    * specification is introduced by the character %. For a description of the
    * available conversion specifiers refer to section 4.9.6.1 in the ANSI
    * draft mentioned at the start of this file or to any modern textbook on C.
    * The minimum value for the maximum number of characters producable by any
    * single conversion is at least 509.
    * Returns: the number of characters transmitted, or a negative value if an
    *          output error occurred.
    */
#pragma __printf_args
extern _ARMABI int _fprintf(FILE * __restrict /*stream*/,
                     const char * __restrict /*format*/, ...) __attribute__((__nonnull__(1,2)));
   /*
    * is equivalent to fprintf, but does not support floating-point formats.
    * You can use instead of fprintf to improve code size.
    * Returns: as fprintf.
    */
#pragma __printf_args
extern _ARMABI int printf(const char * __restrict /*format*/, ...) __attribute__((__nonnull__(1)));
   /*
    * is equivalent to fprintf with the argument stdout interposed before the
    * arguments to printf.
    * Returns: the number of characters transmitted, or a negative value if an
    *          output error occurred.
    */
#pragma __printf_args
extern _ARMABI int _printf(const char * __restrict /*format*/, ...) __attribute__((__nonnull__(1)));
   /*
    * is equivalent to printf, but does not support floating-point formats.
    * You can use instead of printf to improve code size.
    * Returns: as printf.
    */
#pragma __printf_args
extern _ARMABI int sprintf(char * __restrict /*s*/, const char * __restrict /*format*/, ...) __attribute__((__nonnull__(1,2)));
   /*
    * is equivalent to fprintf, except that the argument s specifies an array
    * into which the generated output is to be written, rather than to a
    * stream. A null character is written at the end of the characters written;
    * it is not counted as part of the returned sum.
    * Returns: the number of characters written to the array, not counting the
    *          terminating null character.
    */
extern _ARMABI int vsprintf(char * __restrict /*s*/,
                     const char * __restrict /*format*/, __va_list /*arg*/) __attribute__((__nonnull__(1,2)));
   /*
    * is equivalent to sprintf, with the variable argument list replaced by
    * arg, which has been initialised by the va_start macro (and possibly
    * subsequent va_arg calls). The vsprintf function does not invoke the
    * va_end function.
    * Returns: the number of characters written in the array, not counting the
    *          terminating null character.
    */---------------------------------------------

看stdio.h头文件里面，我颜色标明的部分，已经说明不支持float了。

我的767用printf，还是sprintf都可以打印浮点的。
头文件里面有个编译开关：
#pragma __printf_args
控制着具体的函数实现方式，你用CUBEMX生成工程看看，可能CUBE默认的编译开关支持浮点。
sprintf用起来真不省心，很有可能不是你想象的结果。