Thread: FEOF Error

Hello, I am attempting to write a program that reads some text from a file, formats it, and then writes it to a different file. I originally wrote the program on windows and it ran fine. When I tried to run it on unix, however, reading the text file caused an infinite loop. I am using !feof to test if it has reached the end of file and getc to read the characters 1 at a time.

I am new to unix and used pico to create a text file. Is there a certain eof character I need to add to the end or something?

Any help would be greatly appreciated.....here is the code for reference (Sorry if its messy >.<)

Code:

#include <stdio.h>
#include <assert.h>


int main()
{
        FILE *fp; //Input File
        FILE *fp2; //Output File
        char input_filename[50];
        char output_filename[50];
        
        char text[10000];  //Holds formatted text
        char buffer[100]; //Holds 1 line at a time
        char c;
        
        int i=0;
        int j=0;
        int k=0;
        int l=0;  
        
        int pos=0; //Position in the text array
        int max=30; //Width of text 
        int words=0; //Number of words in buffer array
        int difference=0; //Max-line_len
        int spaces=0; //Difference/words  
        int word_len=0;
        int line_len=0;
        int adjust=0; //Number of spaces added to line        
        int paragraph=0; //1 if new paragraph, 0 if not
        
        printf("Please enter the input filename\n");
        scanf("%s", &input_filename);
        fp = fopen(input_filename, "r");
        
        printf("Please enter the output filename\n");
        scanf("%s", &output_filename);
        fp2 = fopen(output_filename, "w");
        
        printf("Please enter the width\n");
        scanf("%d", &max);   

        max++;
        while(!feof(fp))
        {                      
                      c=fgetc(fp); //Reads from text file 1 character at a time
                      if (feof(fp))
                      {
                          
                          if (line_len+word_len>max)  //Checks if the final line is too long                        
                                 c=' ';                          
                      }
                      else if (c=='\n') //Handles new line formatting
                      {
                          c=fgetc(fp);   
                          if (c=='\n')  //Handles new paragraph formatting
                          {
                             if (line_len+word_len>max)
                             {
                                 c=' ';
                                 fseek( fp , -2 , SEEK_CUR );
                             }
                             else   
                             {   
                                 line_len=line_len+word_len;
                                 word_len=0;                             
                                 words++;                                                 
                                 paragraph=1; 
                                 adjust=1;                                  
                             }                
                          }
                          else //Adjusts location in file stream if not new paragraph
                          {                                                     
                             c=' ';                                                 
                             fseek( fp , -1 , SEEK_CUR );
                          }
                       }
                       
                       
                       if (c!=' '&&paragraph!=1) //Forms a word
                       {                      
                           buffer[i]=c;      
                           word_len++;
                           i++;
                       }                                         
                       else if (word_len+line_len<max&&paragraph!=1) //Checks if the next word will fit on the line
                       {                             
                           line_len=line_len+word_len+1;
                           word_len=0;
                           buffer[i++]=' ';
                           words++; 
                       }
                       else
                       {                           
                           difference=max-line_len; 
                           if (paragraph==1)
                              difference--;
                           spaces=difference/(words);  
                           for(j=0;j<max-adjust;++j)
                           {                                                                                                                          
                               text[pos]=buffer[j];
                               pos++;   
                                
                               if (buffer[j]==' ') 
                               {
                                  words--;
                                  if (words==1) //Checks if it is the last word in the line
                                  {                                            
                                     for(k=0;k<difference;k++) //fill in remainding spaces
                                     {
                                          text[pos]=' ';
                                          pos++; 
                                          adjust++;                                         
                                     }                                      
                                     for(j++;j<max-adjust;++j) //Copies remaining word
                                     {
                                          text[pos]=buffer[j];
                                          pos++;                                                        
                                     }
                                      
                                   } 
                                   else
                                   {                                       
                                       
                                      if (spaces!=0)
                                      {
                                          for (k=0;k<spaces;k++) //Distributes spaces evenly
                                          {
                                              text[pos]=' ';
                                              difference--;
                                              pos++;
                                              adjust++;
                                          }
                                      }
                                      else if (difference>0)                                      
                                      {
                                          text[pos]=' ';
                                          difference--;
                                          pos++;
                                          adjust++;
                                      }
                                    
                                    }       
                                  
                               }   
                           }
                           
                           
                           if (paragraph==1)
                           {                  
                               text[pos]='\n';
                               pos++;
                               text[pos]='\n';      
                               pos++; 
                               for (l=0;l<max+15;l++) //Clears the entire array                                                 
                                   buffer[l]='\0';
                               line_len=0;
                               i=0;
                               word_len=0;
                               words=0;
                               adjust=0;
                               paragraph=0;   
                           }          
                           else
                           {
                               for (l=0;l<word_len;l++)  //Shifts the remaining word to the beginning of the array
                               {        
                                    if (l==0&&buffer[line_len]==' ')
                                    {                                 
                                       line_len++;
                                       l--;
                                    }
                                    else
                                    {
                                         buffer[l]=buffer[line_len];
                                         line_len++;                                     
                                    }
                               }           
                               for (;l<max+15;l++) //Clears the remainder of the array                                                 
                                   buffer[l]='\0';
                                       
                                                                             
                               text[pos]='\n';      
                               pos++;                             
                               line_len=word_len+1;                           
                               i=word_len;
                               buffer[i++]=' ';                          
                               word_len=0;           
                               words=1;
                               adjust=0;
                           }
                           
                       }
               
        }


        fclose(fp);
        fclose(fp2);
}

> char c;
Declaring c as an int will likely fix your problem. Also a better way to control the loop is:

Code:

        while((c=fgetc(fp)) != EOF)
        {

You should avoid using feof() to control a loop: it is usually incorrect, unless reading from the stream is the last thing you do before going to the next iteration.

However, that may not be the current problem. I suggest that you indent your code more consistently and separate the code in that huge while loop into functions that are well named.

Originally Posted by kitaman27

I also tried using while(c=fgetc(fp)) != '\0') to control the loop, but had the same problem with an infinite loop.

As swoopy pointed out, it should be:

Code:

while((c = fgetc(fp)) != EOF)

where c is an int

Originally Posted by kitaman27

while((c = fgetc(fp)) != EOF) where c is an int

still doesn't work for some reason. I'm not sure why it would work fine on windows, but not on unix.

Test with a simpler example, e.g.,

Code:

#include <stdio.h>
#include <string.h>

void getInputFilename(char *input_filename, size_t size);

int main(void)
{
    FILE *fp;
    char input_filename[50];

    getInputFilename(input_filename, sizeof(input_filename));

    fp = fopen(input_filename, "r");
    if (fp)
    {
        int c;
        printf("The content of '%s' is:\n", input_filename);
        while ((c = fgetc(fp)) != EOF)
        {
            putchar(c);
        }
        fclose(fp);
    }
    else
    {
        printf("Could not open '%s'\n", input_filename);
    }
    return 0;
}

void getInputFilename(char *input_filename, size_t size)
{
    char *newline;
    printf("Please enter the input filename: ");
    fgets(input_filename, size, stdin);
    newline = strchr(input_filename, '\n');
    if (newline)
    {
        *newline = '\0';
    }
}