在C中写入文件的问题

问题描述

嗨朋友

当我从图像文件中只读取64个字节时，我看到程序写的是奇怪的字节：

P5

＃创建作者：Imlib

512 512

255

¢¢¢¢??£¢¢ >£ > ?? ¡¡¡¡?? ?? ?? ?? ?? ?? ?? ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >
我尝试过的事情：

hi friends
when i read only 64 bytes from image file i see that the program write strange byte :
P5
# Created by Imlib
512 512
255
¢¢¢¡¢£¡¦¢¢ ›£ ›œ¡¡šœš™š˜œšÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ..
why the program write the """Í""" bytess????

What I have tried:

//while (!feof(file))  // repeat until reached end of file

{
	char *filename="temp_file()";

	pFile=fopen(filename,"wb");

    int index;	// index into the buffer

    numread = fread(buffer, sizeof(unsigned char), 64, fpIn);

    if (numread == 0)

        break;  // no data left to read

    for (index = 0; index < numread; ++index)

    {
        // process each byte of the buffer

        char b = buffer[index];	// b contains the value of the current byte

        //printf("byte %d: %c\", index, b);

		fprintf(pFile,"%c",b);

    }

推荐答案

#include <iostream> // cout, cerr
#include <fstream> // ifstream
#include <sstream> // stringstream
using namespace std;

int main() {
  int row = 0, col = 0, numrows = 0, numcols = 0;
  ifstream infile("file.pgm");
  stringstream ss;
  string inputLine = "";

  // First line : version
  getline(infile,inputLine);
  if(inputLine.compare("P2") != 0) cerr << "Version error" << endl;
  else cout << "Version : " << inputLine << endl;

  // Second line : comment
  getline(infile,inputLine);
  cout << "Comment : " << inputLine << endl;

  // Continue with a stringstream
  ss << infile.rdbuf();
  // Third line : size
  ss >> numcols >> numrows;
  cout << numcols << " columns and " << numrows << " rows" << endl;

  int array[numrows][numcols];

  // Following lines : data
  for(row = 0; row < numrows; ++row)
    for (col = 0; col < numcols; ++col) ss >> array[row][col];

  // Now print the array to see the result
  for(row = 0; row < numrows; ++row) {
    for(col = 0; col < numcols; ++col) {
      cout << array[row][col] << " ";
    }
    cout << endl;
  }
  infile.close();
}

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