Example Code doesn't work!

Hi,

I'm working through Kernighan and Ritchie's The C Programming Language and have copied example code (see below) into Code Blocks to improve my understanding of how it works. Unfortunately I'm getting the error: 'conflicting types for 'getline'...

Code:

#include <stdio.h>
# define MAXLINE 1000

int getline(char line[], int maxline);
void copy(char to[], char from[]);

int main() /* print longest input line */
{
int len;
int max;
char line[MAXLINE];
char longest[MAXLINE];

max = 0;
while ((len = getline(line, MAXLINE)) > 0)
    if (len > max) {
        max = len;
        copy(longest, line);}

if (max > 0) printf("%s", longest);

    return 0;}

/* getline: read a line into s, return length */
int getline(char s[], int lim)
{
int c, i;

for (i = 0; i < lim - 1 && (c = getchar()) != EOF && c != 10; ++i)
    s[i] = c;
if (c == 10) {
    s[i] = c;
    ++i;}

s[i] = '\0';
return i;}

/* copy: copy 'from' into 'to'; assume to is big enough */
void copy(char to[], char from[])
{
int i;

i = 0;
while ((to[i] - from[i]) != '\0')
    ++i;}

Any ideas why this is happening?

Code:

int getline(char line[], int maxline);
...
int getline(char s[], int lim)

If you're going to include the argument names in the function prototype, you'd better match the names, otherwise you can have a function prototype like:

Code:

int getline(char[], int);

I get no compiler warnings or error on this code.
You might want to check this line of code:

Code:

while ((to[i] - from[i]) != '\0') ++i;

Thanks for your suggestion Epy, although, I've implemented it (see below) and still get the same problem:

Code:

#include <stdio.h>
# define MAXLINE 1000

int getline(char[], int);
void copy(char to[], char from[]);

int main() /* print longest input line */
{
int len;
int max;
char line[MAXLINE];
char longest[MAXLINE];

max = 0;
while ((len = getline(line, MAXLINE)) > 0)
    if (len > max) {
        max = len;
        copy(longest, line);}

if (max > 0) printf("%s", longest);

    return 0;}

/* getline: read a line into s, return length */
int getline(char s[], int lim)
{
int c, i;

for (i = 0; i < lim - 1 && (c = getchar()) != 33 && c != 10; ++i)
    s[i] = c;
if (c == 10) {
    s[i] = c;
    ++i;}

s[i] = '\0';
return i;}

/* copy: copy 'from' into 'to'; assume to is big enough */
void copy(char to[], char from[])
{
int i;

i = 0;
while ((to[i] - from[i]) != '\0')
    ++i;}

Following Dino, do you think that there is something wrong with my setup? I'm using Ubuntu 9.1 with C::B 8.02.

Originally Posted by Kayl669

I'm working through Kernighan and Ritchie's The C Programming Language and have copied example code (see below) into Code Blocks to improve my understanding of how it works. Unfortunately I'm getting the error: 'conflicting types for 'getline'...

Rename getline to say, Kayl669_getline. There may be a getline function available via <stdio.h> that is coming into conflict with your code.

Thanks laserlight; that's resolved the issue! Is there someway I can query my <stdio.h> to see what functions it contains?

If you are on linux, getline() is a GNU extension defined in stdio.h

Line Input - The GNU C Library

The only way to query stdio.h I can think of is grep:

grep getline /usr/include/stdio.h
extern _IO_ssize_t getline (char **__restrict __lineptr,
Press any key to continue...

"conflicting types" is a pretty good clue. If changing the name resolves that, then this is for sure the problem and just leave the name changed.

OK. Thanks all. Very helpful. Dino I've sorted my mistype thanks for pointing it out.

Try something like
gcc -ansi prog.c

Then you'll only have the ANSI interface to deal with, and not a lot of extra "helpful" functions declared for you by the compiler vendor.