Thread: K & R exercise - which code would you prefer?

Hello,

I tried to code one of the exercises in K&R, namely the one in which you are supposed to read the input and output it one word per line.

I've come up with two functions, the only difference being in the else block. I think the else block in the first function shows better coding practice (the variable "state" gets changed only when necessary) whereas in the second function it is more compact.

Which of those two functions would you choose?

I tried googling this exercise and most sample answers prefer the second example, which surprises me.

Code:

#include <stdio.h>

#define IN   1  /* inside a word */
#define OUT  0  /* outside a word */

void output1()
{
    int c, state;
    state = OUT;
    while ((c = getchar()) != EOF) {
        if (c == ' ' || c == '\n' || c == '\t')
        {
            if (state == IN)
            {
                putchar('\n');
                state = OUT;   
            }
        }
        else
        {
            if (state == OUT)
                state = IN;
            putchar(c);
        }
    }
}

void output2()
{
    int c, state;
    state = OUT;
    while ((c = getchar()) != EOF) {
        if (c == ' ' || c == '\n' || c == '\t')
        {
            if (state == IN)
            {
                putchar('\n');
                state = OUT;   
            }
        }
        else
        {
            state = IN;
            putchar(c);
        }            
    }
}

I think you've got the else going to the wrong if there, Tater.

The first one is in theory less efficient, as the if will take longer than the assignment regardless of whether the assignment is necessary. Technically the same is true of the first one, but there the logic is different so you have to do the check anyway.

Originally Posted by tabstop

I think you've got the else going to the wrong if there, Tater.

The first one is in theory less efficient, as the if will take longer than the assignment regardless of whether the assignment is necessary. Technically the same is true of the first one, but there the logic is different so you have to do the check anyway.

Go ahead... set state = 3 and watch what happens...

Originally Posted by CommonTater

Go ahead... set state = 3 and watch what happens...

Why would one want to do that in the first place? :-)

How would you improve the code then, please?

I tried to write two pieces of code that would be clean, readable and as much "textbook-like" as possible, where did I fail then?

Thanks in advance for your answers,

Caroline

Originally Posted by kkk

Why would one want to do that in the first place? :-)

How would you improve the code then, please?

I tried to write two pieces of code that would be clean, readable and as much "textbook-like" as possible, where did I fail then?

Thanks in advance for your answers,

Caroline

Because it's an error condition... it's just as important to see how a program screws up as it is to get it running in the first place... You'll be amazed what you can learn watching something crash and burn...

Originally Posted by quzah

we've learned a lot from tater!
quzah.

sigh