Practical C Programming, Third Edition

Hey all :-) I am new to the forums and have decided to try and learn C.

The book I am using to teach myself C is "Practical C Programming, Third Edition" by O'Reilly.

I am on chapter 6 and am stuck on programming exercise 6-2.

Does anybody know of a website that has the answers to the exercises at the end of each chapter?

OK, I have figured out the answer to question 6-2. For anyone who wants to know here it is

Code:

---

#include <stdio.h>

char    line[4];
int    grade;



int main ()
{

        printf ("What is the numeric grade: ");
        fgets(line, sizeof(line), stdin);
        sscanf(line, "%d", &grade);

        if (grade <= 60)
                printf("F\n");

        if (grade >= 61)
                while (grade <= 70)
                {
                printf("D\n");
                break;
                }

        if (grade >= 71)
                while (grade <= 80)
                {
                printf("C\n");
                break;
                }

        if (grade >= 81)
                while (grade <= 90)
                {
                printf("B\n");
                break;
                }

        if (grade >= 91)
                printf("A\n");
return(0);
}

---

I am still interested in knowing if there are answers on some website to the questions at the end of each chapter.

lol what?

have you heard of else if? because loops that are guaranteed to only loop once make my eyes bleed

Code:

---

#include <stdio.h>

int main ()
{
       
        char    line[4];
        int    grade;

        printf ("What is the numeric grade: ");
        fgets(line, sizeof(line), stdin);
        sscanf(line, "%d", &grade);

        if (grade < 60)
                printf("F\n");
        else if (grade < 70)
                printf("D\n");
        else if (grade < 80)
                printf("C\n");
        else if (grade < 90)
                printf("B\n");
        else
                printf("A\n");
return 0;
}

---

and what is line for anyway?

The book, so far, doesn't mention "else if". I am answering the question with what I have learned so far. I am aware there are probably more elegant ways of answering this question but I haven't learned that yet.

Quote:

---

Originally Posted by jc99

The book, so far, doesn't mention "else if". I am answering the question with what I have learned so far. I am aware there are probably more elegant ways of answering this question but I haven't learned that yet. :D

---

O.O

I'd get a new book

Are you talking about

Code:

---

char line[4];

---

I am still a little confused what I need it for. I thought I needed it so I can use fgets and sscanf to get the grade I entered into the program when I run it :D

It's the memory that you allocate to store input from stdin.

Quote:

---

Originally Posted by jc99

The book, so far, doesn't mention "else if". I am answering the question with what I have learned so far. I am aware there are probably more elegant ways of answering this question but I haven't learned that yet.

---

You should always check your facts. Given that "else" is covered in section 6.2, which is before the programming exercise under consideration.....

You could be using line to validate input -- you went to all the trouble to read a string and then read out of string -- but you don't handle bad input. (Neither does the author of your book, so we'll forgive you this once.)

Quote:

---

Originally Posted by tabstop

You should always check your facts. Given that "else" is covered in section 6.2, which is before the programming exercise under consideration.....

---

Maybe I am missing it but I am re-reading chp6 (on page 85) and all I can find is...

Code:

---

if (condition)
  statement;
else
  statement;

---

Which is "if else" I see no mention of "else if". I was unaware I could do "else if" but will keep it in mind for future programs I write.

else if is the same as

Code:

---

if (condition)
    statement;
else
    if (condition2)
          statement;

---

You can chain as many of them as you want.

It's just more conventionally written as

Code:

---

if (condition)
    statement;
else if (condition2)
    statement;

---

To the compiler they are the same (remember that compilers ignore indentation).

And

Code:

---

        if (grade >= 61)
                while (grade <= 70)

---

in your case, is the same as

Code:

---

    if (grade >= 61)
          if (grade <= 70)

---

which is the same as (but you might not have learned this yet)

Code:

---

    if (grade >= 61 && grade <= 70)

---

and then, if you use else, you can simplify it further to ಠ_ಠ's version. Only one condition is needed per letter grade, because, for example,

Code:

---

else if (grade < 70)

---

won't be evaluated if grade < 60.