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            ???? 可能有好多人,包括C語言老手都不知道如何將float數(shù)據(jù)轉(zhuǎn)換為string,我就是這樣,今天查了一下MSDN,才知道C提供了_gcvt函數(shù)實現(xiàn)這個功能,收獲著實不小,為了方便自己查詢,也為了那些像我這樣的網(wǎng)友能夠了解該函數(shù)的具體用法,我把MSDN的原文原封不動抄錄如下:

            _gcvt

            Converts a floating-point value to a string, which it stores in a buffer.

            char *_gcvt( double value , int digits , char * buffer );

            Routine Required Header Compatibility
            _gcvt <stdlib.h> Win 95, Win NT

            For additional compatibility information, see Compatibility in the Introduction.

            Libraries

            LIBC.LIB Single thread static library, retail version
            LIBCMT.LIB Multithread static library, retail version
            MSVCRT.LIB Import library for MSVCRT.DLL, retail version

            Return Value

            _gcvt returns a pointer to the string of digits. There is no error return.

            Parameters

            value

            Value to be converted

            digits

            Number of significant digits stored

            buffer

            Storage location for result

            Remarks

            The _gcvt function converts a floating-point value to a character string (which includes a decimal point and a possible sign byte) and stores the string in buffer. The buffer should be large enough to accommodate the converted value plus a terminating null character, which is appended automatically. If a buffer size of digits + 1 is used, the function overwrites the end of the buffer. This is because the converted string includes a decimal point and can contain sign and exponent information. There is no provision for overflow. _gcvt attempts to produce digits digits in decimal format. If it cannot, it produces digits digits in exponential format. Trailing zeros may be suppressed in the conversion.

            Example

            								/* _GCVT.C: This program converts -3.1415e5 * to its string representation. */#include <stdlib.h>#include <stdio.h>void main( void ){   char buffer[50];   double source = -3.1415e5;   _gcvt( source, 7, buffer );   printf( "source: %f  buffer: '%s'\n", source, buffer );   _gcvt( source, 7, buffer );   printf( "source: %e  buffer: '%s'\n", source, buffer );}
            						

            Output

            								source: -314150.000000  buffer: '-314150.'source: -3.141500e+005  buffer: '-314150.'
            						


            Trackback: http://tb.blog.csdn.net/TrackBack.aspx?PostId=708935


            [收藏到我的網(wǎng)摘]?? skyman_2001發(fā)表于 2006年05月05日 11:28:00



            #??lanno?發(fā)表于2006-05-05 18:26:00??IP: 222.35.68.*
            長見識了,俺總是這樣轉(zhuǎn)化的:
            char str[260];
            float f = -3.1415926;
            float f1 = 263e-5;
            sprintf(str,"%f",f);
            printf("%s\n",str);
            sprintf(str,"%f",f1);
            printf("%s\n",str);

            #??Skyman?發(fā)表于2006-05-05 21:35:00??IP: 202.202.10.*
            你這樣做也行
            但沒有這樣靈活
            是吧?

            #??zhnde?發(fā)表于2006-05-11 20:15:00??IP: 129.69.212.*
            靈活嗎? 能具體解釋一下嗎?

            #??Skyman?發(fā)表于2006-05-11 22:03:00??IP: 202.202.10.*
            至少可以方便的控制有效數(shù)字的位數(shù)啊。

            #??ztwaker?發(fā)表于2006-07-28 12:40:00??IP: 61.144.207.*
            /*C++ impl*/
            string cvt(const float fval)
            {
            stringstream ss;
            ss << fval;
            return ss.str();
            }

            ......///

            #??ztwaker?發(fā)表于2006-07-28 12:46:00??IP: 61.144.207.*
            加上有效數(shù)字位數(shù)控制

            string cvt(const float f, const int prec)
            {
            stringstream ss;
            ss.precision(prec);
            ss << f;
            return ss.str();
            }

            posted on 2006-12-15 11:18 清源游民 閱讀(9241) 評論(1)  編輯 收藏 引用 所屬分類: C++

            FeedBack:
            # re: 如何將float轉(zhuǎn)換為string
            2011-09-06 09:56 | 明樣
            不知道_gcvt是C標(biāo)準(zhǔn)函數(shù)還是只是MS的擴(kuò)展?
            如果不是標(biāo)準(zhǔn)函數(shù)的話還是不建議使用,沒有移值性就談不上靈活……  回復(fù)  更多評論
              
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