用C语言读取限制字节 [英] Read limit byte with C language

问题描述

嘿大家

i有一个图像，我想当我开始通过c编程中的文件读取图像，按块读取或者之前定义的限制字节数，这意味着读取限制字节例如32字节，在我想要计算该块中每个字节的概率之后

thankx



我有什么试过：



FILE * fp = fopen（image.pgm，rb）

while（c = fgetc（fp）！= EOF）

{

//读取第32个字节

//计算每个字节的概率

//返回文件中的位置32

}

解决方案

你什么也没做，我们没有做你的作业。



你最好学习C，并按照tutos：



C编程语言 - 维基百科，免费的百科全书 [ ^ ]

https://hassanolity.files.wordpress.com/2013/11/the_c_programming_language_2.pdf [ ^ ]

http://www.ime.usp.br/~pf/Kernighan-Ritchie/C-Programming-Ebook.pdf [ ^ ]

不要使用 fgetc 来读取文件，尤其是二进制数据。按照 https：// msdn中所述使用 fread 。 microsoft.com/en-us/library/kt0etdcs.aspx [ ^ ]。

这是读取文件的基本代码

 < span class =code-keyword> unsigned   char  buffer [ 64 ];  //  缓冲区可以是任意大小 
 FILE * fp = fopen（  image.pgm，  RB）; 
  int  numread; 
 
  while （！feof（fp）） //  重复，直到达到文件结尾 
 {
  int  index;  //  缓冲区索引 
 numread = fread（buffer， sizeof （ unsigned   char ）， 64 ，fp）; 
  if （numread ==  0 ）
 断裂;  //  无需读取数据 
  for （index =  0 ; index< numread; ++ index）
 {
  //  处理缓冲区的每个字节 
  int  b = buffer [指数];  //   b包含当前字节的值 
 printf（  byte％d：％d \ n，index，b）; 
} 
} 

hey everyone
i have a image , i want when i start to read the image by the file in c programming , read by block or a limit number of byte defined before , it means read a limit byte for example 32 byte , after i want to calculate the probability for every byte in this block
thankx

What I have tried:

FILE *fp=fopen("image.pgm","rb")
while (c=fgetc(fp)!=EOF)
{
//read the 32 first byte
//calcule the probability of every byte
//return to position 32 in the file
}

解决方案

You have done nothing and we don't do your homework.

You better learn C properly, and follow tutos:

The C Programming Language - Wikipedia, the free encyclopedia[^]
https://hassanolity.files.wordpress.com/2013/11/the_c_programming_language_2.pdf[^]
http://www.ime.usp.br/~pf/Kernighan-Ritchie/C-Programming-Ebook.pdf[^]

Do not use fgetc to read files, especially binary data. Use fread as described at https://msdn.microsoft.com/en-us/library/kt0etdcs.aspx[^].

This is the very basic code to read the file

unsigned char buffer[64];	// buffer may be any size
FILE *fp = fopen("image.pgm", "rb");
int numread;

while (!feof(fp))  // repeat until reached end of file
{
    int index;	// index into the buffer
    numread = fread(buffer, sizeof(unsigned char), 64, fp);
    if (numread == 0)
        break;  // no data left to read
    for (index = 0; index < numread; ++index)
    {
        // process each byte of the buffer
        int b = buffer[index];	// b contains the value of the current byte
        printf("byte %d: %d\n", index, b);
    }
}

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