not giving the correct count for number of lines-CodePudding

the code isn't counting correctly as all the numbers in the output are lower than they should be. I can't find any reason as to why I'm getting these numbers as I still don't understand c very well.

if I read in a file with 25 lines and 20 lines excluding white space and comments the output from my code will be 10 and -13 and I'm not sure why. Any help is greatly appreciated.

#include <stdio.h>
#include <string.h>
#define LINE_LENGTH 1000
    
int main(int argc, char **argv)
{   
    FILE *input_file = fopen("cstest.c", "r");
        
        
    char line [LINE_LENGTH];
        
    //while loop to get
    while(fgets(line,LINE_LENGTH,input_file)!=NULL)
    {   
        int ch=0;//ch is the cast
        int lines=0;
    
        if (input_file == NULL) 
            return 0;
        
        while(fgetc(input_file)!= EOF)
        {
    
            ch = fgetc(input_file);
    
            if(ch == '\n')
            {
                lines  ;
            }
            
        
        }//end while
        printf("lines: %d\n",lines);
    }//end while loop 

    
    rewind(input_file);
        
        
    while(fgets(line,LINE_LENGTH,input_file)!=NULL)
    {   
        int ch=0;//ch is the cast
        int lines=0;
        char c;
        if (input_file == NULL) 
            return 0;
        
        while(fgetc(input_file)!= EOF)
        {
            ch = fgetc(input_file);
            if(ch == '\n')
            {
                lines  ;
            }
    
            if(ch == '\n' && ch   1 == '\n' || ch == '\t')
            {
                lines--;
            }
        
        
    
        }//end while
        
        printf("lines excluding white space and comments: %d\n",lines);
        

    }//end while loop

    fclose(input_file);
}

CodePudding user response：

You're skipping lots of things.

First, a line is read by this condition:

while(fgets(line,LINE_LENGTH,input_file)!=NULL)

This line won't be read by the later fgetc() calls. So you never count the newline at the end of this line.

Then in your next loop:

        while(fgetc(input_file)!= EOF)
        {
            ch = fgetc(input_file);
            if(ch == '\n')
            {
                lines  ;
            }
        }//end while

you only check every other character to see if it's a newline. You read one character in the while() condition and just check if it's EOF. Then you read another character in the loop body and test if it's `\n'.

You don't need the nested loops or multiple calls to fgetc().

    int ch;
    while((ch = fgetc(input_file))!= EOF)
    {
        if(ch == '\n')
        {
            lines  ;
        }
            
        
    }//end while
    printf("lines: %d\n",lines);

CodePudding user response：

You only need one loop, fgets is reading the whole line for you. Barmar fixes it one way , I went the other way.

int lines = 0;
//while loop to get
while (fgets(line, LINE_LENGTH, input_file) != NULL)
{
    int ch = 0;//ch is the cast
    lines  ;

      //while (fgetc(input_file) != EOF)
    //{

    //    ch = fgetc(input_file);

    //    if (ch == '\n')
    //    {
    //        lines  ;
    //    }


    //}//end while
    printf("lines: %d\n", lines);
}//end while loop