问题描述
大家好，我不是C的新手，但是我已经超过5年才使用它了...
我正试图读取一个有两倍的文本文件：
1.0 1.1 1.2 1.3 1.4
2.0 2.1 2.2 2.3 2.4
我'这样做（这只是试图达到目标的一个考验......）：
#include< stdio.h>
#include< stdlib.h>
int main（）{
FILE * pFile;
long lSize;
double * buffer;
pFile = fopen（" fichero_test.txt"，" r"）;
if（pFile == NULL）退出（1）;
//获取文件大小。
fseek（pFile，0，SEEK_END）;
lSize = ftell（pFile）;
倒带（pFile）;
//分配内存以包含整个文件。
buffer =（double *）malloc（lSize）;
if（buffer == NULL）exit（2）;
//复制文件进入缓冲区。
fread（缓冲区，1，lSize，pFile）;
printf（" Pos 2 - ％lf \ n"，buffer [2]）;
printf（" Pos 2 - ％lf \ n"，buffer [sizeof（double）* 2]）;
//终止
fclose（pFile）;
免费（缓冲）;
返回0;
}
输出结果为：
Pos 2 - 0.000000
Pos 2 - 0.000000
我做错了什么？，我可以将整个文件读入一个缓冲区？
Hi all, I''m not a newbie with C, but I don''t use it since more than 5 years...
I''m trying to read a text file which has doubles in it:
1.0 1.1 1.2 1.3 1.4
2.0 2.1 2.2 2.3 2.4
I''m doing this (it''s only a test trying to achieve the goal...):
#include <stdio.h>
#include <stdlib.h>
int main () {
FILE* pFile;
long lSize;
double* buffer;
pFile = fopen ( "fichero_test.txt" , "r" );
if (pFile==NULL) exit (1);
// obtain file size.
fseek (pFile , 0 , SEEK_END);
lSize = ftell (pFile);
rewind (pFile);
// allocate memory to contain the whole file.
buffer = (double*) malloc (lSize);
if (buffer == NULL) exit (2);
// copy the file into the buffer.
fread (buffer,1,lSize,pFile);
printf("Pos 2 - %lf\n", buffer[2]);
printf("Pos 2 - %lf\n", buffer[sizeof(double)*2]);
// terminate
fclose (pFile);
free (buffer);
return 0;
}
The output is:
Pos 2 - 0.000000
Pos 2 - 0.000000
What am I doing wrong?, Can I read the whole file into a buffer?
推荐答案
是的，但你必须从字符转换为双。最好的
组合是fgets（）读取一行，然后是sscanf（）来解析
行。
总是检查返回值of sscanf（）。
-
Nick Keighley
yes, but you have to convert from characters to double. The best
combination is fgets() to read a line followed by sscanf() to parse the
line.
Always check the return value of sscanf().
--
Nick Keighley
void read_line（double dd [5]，FILE * f）
{
if（fscanf（f，"％lf％lf％lf％lf％lf"，& dd [0]，& dd [1]，& dd [2]，
& ; dd [3]，& dd [4]
！= 5）
{
退出（EXIT_FAILURE）;
}
}
void read_line (double dd [5], FILE *f)
{
if (fscanf(f, "%lf %lf %lf %lf %lf", &dd[0], &dd[1], &dd[2],
&dd[3], &dd[4)
!= 5)
{
exit (EXIT_FAILURE);
}
}
好吧，它对我不起作用，因为真实文件每行可以有5,6或1000个项目。
Well, it doesn''t works for me because the real file could have 5, 6 or 1000 items per line.
我不确定这是否适用于文本文件...
I''m not certain this works on a text file...
确实...
It does...
ok
你不能把字符填充到一个缓冲区中，并期待理智的结果。
是的，我想是的，但我不确定，这就是我要求帮助的原因....
是的，但你必须从字符转换为double。最好的组合是fgets（）读取一行，然后是sscanf（）来解析
行。
我认为没有readLine函数，所以我需要阅读，直到我达到''\ n''字符，不是吗？ br />
总是检查sscanf（）的返回值。
ok
You can''t jsut stuff characters into a buffer and expect sane results.
Yeah, I guess that, but I wasn''t sure of it, that''s the reason I''ve asked for help....
yes, but you have to convert from characters to double. The best
combination is fgets() to read a line followed by sscanf() to parse the
line.
I suppose there isn''t a readLine function, so I''ll need to read until I reach a ''\n'' character, isn''t it?
Always check the return value of sscanf().
这个帖子在''c file reading''帮助吗？
-
===== =========
不是学生
==============
Does this thread on ''c file reading'' help?
http://groups.google.com/group/comp....41f9f1ba8ac3d9
--
==============
Not a pedant
==============
这篇关于阅读文件......的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！