fgets is not stopping after \n

Question

I have the following piece of code:

while (fgets(line,1024,file))
{
    getchar();
    printf(line);
    i++;
    line = (char*)realloc(line, sizeof(char)*sizes[i]);
}

and for some reason when I printf the line, it prints two lines. How can it be?

full code:

int main()
{
    FILE * file = fopen("C:/Users/user/Desktop/a.txt","r");
    char c;
    int count=0;
    int words=0;
    int* sizes = (int*)calloc (count+1,sizeof(int));

    if (file)
    {
        do
        {
            c= getc(file);
            words++;

            if (c=='\n'|| c==EOF)
            {
                sizes[count]=words+1;
                count++;
                words=0;
                if (c=='\n')
                    sizes = (int*)realloc(sizes,(count+1)*sizeof(int));
            }
        }while (c!=EOF);

        rewind(file);
        char* line = (char*)malloc(sizeof(char)*(sizes[0]));

        int i=0;
        while (fgets(line,1024,file))
        {
                getchar();
                printf("%s",line);
                i++;
                line=(char*)realloc(line,sizeof(char)*sizes[i]);
        }

        printf(line);

        free(line);

        /*for (int i=0; i<8; i++)
        {
            printf("%d\n",sizes[i]);
        }*/

        free(sizes);
        fclose(file);
    }

    getchar();

    return 0;
}

as you see, I count each line's length, put it into array, than allocate a string according to the line's length.

Answer 1

You have an extra

printf(line);

after the while loop, causing the last line to be printed twice.

if you change the print inside tho loop to

printf("read[%d]: %s", i, line);

it will be more obvious. the same i won't be printed twice. the output may appear to have a line breakn in the middle if you have a strange control sequence like \v\r but it's still the same "line" being printed

Answer 2

if you just press "enter" at getchar there will be one line. if you type 1 letter and enter there will be 2 lines. if you type 2 letters and enter there will be 3 lines

see where i m going. your input breaks at "enter" but getchar is happy with one character and the other is in the buffer which it gets in the next loop.

sample output:

total 192
1 <---------input
-rw-rw-r-- 1 nranjan3 nranjan3  1032 Jun 11  2013 parseCreateList.c
-rw-rw-r-- 1 nranjan3 nranjan3   462 Jun 14  2013 mpSpRec.c
12 <---------input
-rwxrwxr-x 1 nranjan3 nranjan3  8681 Jun 14  2013 mpSpRec.exec
-rw-rw-r-- 1 nranjan3 nranjan3   162 Jul 29  2013 mtTrace.log
-rw-rw-r-- 1 nranjan3 nranjan3  1280 Jul 29  2013 iccLogger.c
123 <---------input
-rwxrwxr-x 1 nranjan3 nranjan3  6662 Aug 20  2013 k.out
-rw-rw-r-- 1 nranjan3 nranjan3  1465 Aug 21  2013 stNewProcPar.c
-rwxrwxr-x 1 nranjan3 nranjan3 11624 Aug 21  2013 masterP
-rw-rw-r-- 1 nranjan3 nranjan3   321 Nov 25  2013 memTest.c

now instead of getchar you add this, it will work and show 1 line irrespective how many letters you type

while (getchar() != '\n');

Answer 3

If you are asking about the extra new line in your code then you need to go for probably to remove the getchar() function. cause due to this it simply waits in new line and when you put enter then you can see the next line from the file. However you looks like that extra line in your output. so exchange the Function:

getchar();

with:

getch();

I hope you probably get the answer.

Answer 4

char c; should be int c;. Since EOF must be different to all possible chars, if you use char c; then either you never find EOF, or you get false positives, depending on your system's format of char.

Moving on:

while (fgets(line,1024,file))

Replace 1024 with sizes[i]. This will prevent a buffer overflow.

{
    getchar();

The getchar() discards the first character of the next line. However if the next line was blank then it means the entire next line is discarded. Then your line counts will be out of sync with the lines you are reading (causing undefined behaviour if you were still using 1024 in fgets, which could explain why you see bogus output).

i++;

You should break out of the loop if i >= count.

As others have mentioned, printf(line); after the loop will mean the last line prints twice (and is garbled if it contained any % characters).

Finally, don't cast malloc. As well as making your code more robust it will make it easier to read. You don't need sizeof(char) either since that is always 1.

NB. It'd be much better to just read the lines as you go, instead of making two passes over the file.