K&R Exercise 1-19: Reverse Char Array - c

Question

I'm able to reverse the array fine, but I can't get the program to terminate when I do CTRL+D(EOF) in terminal.
The only way I can get the program to terminate is if the very first thing I do after compiling is doing CTRL+D. But if I type in one string, then CTRL+D will not work after that.
I'm not quite sure where my error is.
#include <stdio.h>
#define MAXLINE 1000 // Maximum input.
// ----------------- reverseLine -----------------
// This method reads in chars to be put into an
// array to make a string. EOF and \n are the
// delimiters on the chars, then \0 is the
// delimiter for the string itself. Then the
// array is swapped in place to give the reverse
// of the string.
//------------------------------------------------
int reverseLine(char s[], int lim)
{
int c, i, newL;
// c is the individual chars, and i is for indices of the array.
for (i = 0; i < lim - 1 && (c=getchar()) != EOF && c != '\n'; ++i)
{
s[i] = c;
}
if (c == '\n') // This lets me know if the text ended in a new line.
{
newL = 1;
}
// REVERSE
int toSwap;
int end = i-1;
int begin = 0;
while(begin <= end) // Swap the array in place starting from both ends.
{
toSwap = s[begin];
s[begin] = s[end];
s[end] = toSwap;
--end;
++begin;
}
if (newL == 1) // Add the new line if it's there.
{
s[i] = '\n';
++i;
}
s[i] = '\0'; // Terminate the string.
return i;
}
int main()
{
int len;
char line[MAXLINE];
while ((len = reverseLine(line, MAXLINE)) > 0) // If len is zero, then there is no line to recored.
{
printf("%s", line);
}
return 0;
}
The only thing I can think of is the while loop in main checks if len > 0, so if I type EOF, maybe it can't make a valid comparison? But that wouldn't make sense as to why it works when that's the first and only thing I type.

Answer 1

Your program will never read the EOF because of this condition:
(c=getchar()) != EOF && c != '\n';
As soon as c is equal to '\n' the loop terminates and all the following characters are ignored. I think you should separate input from line reversing and make the usual checks on the reverse function parameters.
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define SIZE_MAX (256U)
static bool linereverse(char *line);
static bool deletenewline(char *s);
int main(void)
{
char buff[SIZE_MAX];
bool success;
(void) fputs("Enter a string: ", stdout);
if( NULL == fgets(buff,(size_t) SIZE_MAX, stdin))
{
(void) fputs("Error: invalid input!\n",stderr);
return EXIT_FAILURE;
}
success = deletenewline(buff);
if(false == success)
{
(void) fputs("Error: cannot remove newline\n",stderr);
return EXIT_FAILURE;
}
success = linereverse(buff);
if(false == success)
{
(void) fputs("Error: cannot reverse the line");
return EXIT_FAILURE;
}
(void) fputs("The line reversed is: ", stdout);
(void) fputs(buff, stdout);
(void) puchar('\n');
return EXIT_SUCCESS;
}
static bool linereverse(char *line)
{
size_t i;
size_t j;
char tmp;
if(NULL == line)
{
return false;
}
i = 0;
j = strlen(line) - 1;
while(i < j)
{
tmp = line[i];
line[i] = line[j];
line[j] tmp;
++i;
--j;
}
return true;
}
static bool deletenewline(char *s)
{
char *p;
if(NULL == s)
{
return false;
}
p = strrchr(s,'\n');
if(NULL != p)
{
*p = '\0';
}
return true;
}