stm32f203 使用vsprintf为什么不能显示浮点数？%f没用？
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。
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