printf有时会打印多余的垃圾

Question

I'm parsing through a .ppm file, using fgetc to read a single byte at a time, and then converting them to floats by dividing by 255.0 to get colors for use in OpenGL code. This is easy. I print the numbers out for debugging purposes using printf("%f %f %f\\n", color[0], color[1], color[2]); . Most of the time this works well (see the first line), but occasionally it prints out extra garbage (see the second line).

0.086275 0.031373 0.000000
0.133333 0.000000 0.00<BA><B9>9?<D1><D0><D0>=<99><98>^X>3 0.078431 0.000000

Any ideas why this might be?

UPDATE:

float *read_eight_bit(FILE *file, int rows, int cols)                                                                                                                                                                                                                          
{                                                                                                                                                                                                                                                                              
   float *data = (float *)malloc(rows*cols*3*sizeof(float));                                                                                                                                                                                                                    
   int c;                                                                                                                                                                                                                                                                       
   int i, j, k;                                                                                                                                                                                                                                                                 
   for(i = 0; i < rows; i++) {                                                                                                                                                                                                                                                  
     for(j = 0; j < cols; j++) {                                                                                                                                                                                                                                                
         for(k = 0; k < 3; k++) {                                                                                                                                                                                                                                                 
           if((c = fgetc(file)) != EOF) {                                                                                                                                                                                                                                                              
             data[get_index(i, j, k, rows, cols)] = c/255.0f;                                                                                                                                                                                                                     
           }                                                                                                                                                                                                                                                                      
           else {                                                                                                                                                                                                                                                                 
             perror("reached unexpected EOF");                                                                                                                                                                                                                                    
             free(data);                                                                                                                                                                                                                                                          
             return NULL;                                                                                                                                                                                                                                                         
         }                                                                                                                                                                                                                                                                      
     }                                                                                                                                                                                                                                                                                                                                          
   return data;
}

This is the actual code that reads things in.

Answer 1

The only explanation I can think of without seeing more code is that the stack is messed up somehow, possibly through a buffer over- or underrun (writing outside an array).

I'd recommend running your code through cppcheck , as it can detect many of these sorts of problems.