Thread: Assigning words to numbers

Hi, I'm new to C and I want to have a user input a bunch of grades and calculate the gpa.

I want to have some type of variable whether it's float or int or whatever (i'm not sure what will work, this is part of my question) named grades. In a for command which I already have worked out, when the user is prompted for a grade:

Code:

scanf("%whatever", grades);

If they type in an A, the computer will know that A means 4.00, if they type B, the computer will know that B means 3.00, then I'm going to have a floating point for the variable totalgrades and it will be something like

Code:

totalgrades+=grades;

What I cannot figure out is how to assign the inputted letters numbers.

EDIT: If you want to see the code, I'll paste it but I didn't want to waste space.

char, float, long, int, double, short, byte, long double... all will work
just scanf("%whatever", &grade);

well yes. but it's an ugly way of doing it.

Code:

int totalgrade;
char x, no_of_grades,i;
int main(void) {
     for (i=0;i<no_of_grades;i++) 
          switch(x=toupper(getchar())) {
               case 'A': {totalgrade+=4;break;}
               ...
               }
     printf("%d", (float)totalgrade/(float)no_of_grades);
     return(0);
     }

1. because you only read 1 letter at once, it's 'neater' to use getchar instead.
2. printf("%d", (float)totalgrade/(float)no_of_grades); does a thing called "casting", or changing the way c treats the casted variable. if you only used totalgrade/no_of_grades that would be a integer division (3.0 / 2.0 = 1.5, but 3 / 2 = 1 -- see the difference?)
3. you'll need to include ctype and conio, for toupper() and getchar()

Code:

#include <ctype.h>
#include <conio.h>

4. toupper will make sure that it will work if the user inputs capital or small case letters.
5. if you need more than 127 grades to make an avg, make totalgrade a int or long (mind those who don't have the patience to type in 2 giga of data ).

Originally Posted by moonlord

2. printf("%d", (float)totalgrade/(float)no_of_grades); does a thing called "casting", or changing the way c treats the casted variable. if you only used totalgrade/no_of_grades that would be a integer division (3.0 / 2.0 = 1.5, but 3 / 2 = 1 -- see the difference?)

Here however, "%d" is used for integeral types, and not floating point numbers. So the cast really isn't going to do what you want anyway, because it's still going to display it as an integer, truncating anything past the decimal point anyway.

Originally Posted by moonlord

3. you'll need to include ctype and conio, for toupper() and getchar()

Code:

#include <ctype.h>
#include <conio.h>

Actually, getchar is in <stdio.h>. You're thinking of getch, which is in <conio.h>, which is a non-ANSI function that only some compilers have. (Along with getche.) It's commonly used with people with old compilers in place of getchar, however getchar is a portable version, which behaves slightly different.


Quzah.

missed the %d out there.
the second problem: i don't argue with you, i have never actually used getchar.

You do know they have private messaging here for this sort of thing, right?


Quzah.