Basic c programming help

[benrogers]

I am having a problem with the creating the following program:

Create a program that will read in 2 letters, and then print the character half-way between the two. e.g. given A and G, it will print D. If there are an even number of characters between, then either of the 2 middle ones is OK

I don't understand how I am suppose to have the program print out the character half-way between the two.

Here is what I have.

int main()
{
    char ch, ch1, ch2;
    
    printf("Please enter in two characters.\n");
    scanf("%c %c", &ch, &ch1);

Any help is greatly appreciated.

[Salem]

ASCII - Wikipedia, the free encyclopedia
Notice that A is 65 and F is 70

What is 70 - 65 ?

[benrogers]

ASCII - Wikipedia, the free encyclopedia
Notice that A is 65 and F is 70

What is 70 - 65 ?

ch2 = ch - ch1;
    printf("The number half-way between the two characters your entered is %c.\n", ch2);

?

[Salem]

OK - print this as a letter (%c)

char c = 'A' + 5;

Print the same as an integer (%d)

[benrogers]

OK - print this as a letter (%c)

char c = 'A' + 5;

Print the same as an integer (%d)

I am following you but what is the equation after the first printf?

I have this so far

char ch, ch1;
    
    printf("Please enter in two characters.\n");
    scanf("%c %c", &ch, &ch1);
    printf("You entered %c and %c.\n" , ch, ch1);

I understand your saying to have ch3 or something = - and a printf statement after that saying the middle number but what do I put as the values I am subtracting?

ch2 = ch - ch1;
    printf("The letter half-way between the characters you entered is %c.\n" , ch2);

does not print out the right answer.

[tabstop]

I am following you but what is the equation after the first printf?

I have this so far

char ch, ch1;
    
    printf("Please enter in two characters.\n");
    scanf("%c %c", &ch, &ch1);
    printf("You entered %c and %c.\n" , ch, ch1);

I understand your saying to have ch3 or something = - and a printf statement after that saying the middle number but what do I put as the values I am subtracting?

ch2 = ch - ch1;
    printf("The letter half-way between the characters you entered is %c.\n" , ch2);

does not print out the right answer.

I am curious as to why you think subtracting is involved. How do you find the midpoint of two numbers?

[benrogers]

I am curious as to why you think subtracting is involved. How do you find the midpoint of two numbers?

ahhhhh

    char ch, ch1, ch2, sum;
    
    printf("Please enter in two characters.\n");
    scanf("%c %c", &ch, &ch1);
    printf("You entered %c and %c.\n" , ch, ch1);
    sum = ch + ch1;
    ch2 = sum / 2;
    printf("The letter half-way between the characters you entered is %c.\n" , ch2);

it produces a number not a letter.

[Salem]

But that only works when your baseline is zero.

n = ch - 'A';

Then do some maths

Then do x + 'A' to get back to letters.

[tabstop]

But that only works when your baseline is zero.

n = ch - 'A';

Then do some maths

Then do x + 'A' to get back to letters.

I have no idea what this means. (Finding the average of 65 and 71 doesn't require subtracting 65 from both numbers.)

[benrogers]

I have no idea what this means. (Finding the average of 65 and 71 doesn't require subtracting 65 from both numbers.)

So what would I do to get the character values in order to divide them by 2?

[Salem]

Literal example

'C' - 'A' is 2
'E' - 'A' is 4

( 2 + 4 ) / 2 = 3

3 + 'A' is 'D'

[CommonTater]

So what would I do to get the character values in order to divide them by 2?

Nothing....

ASCII text, like you see in a console screen is really a code, the numbers are offset by 48 the letter by 64 (caps), and 96 (lower)... where you get into trouble is if someone hands your program z and 9 ... not only are these in reverse order per the code, they are at different offsets... so your average might produce an @ sign or something stranger.

Now for a beginner's program my thought would be to get it to work *at all* then worry about all the complications that come along... But at some point you will have to figure out how to confine both letters entered to the same group.

[CommonTater]

Literal example

'C' - 'A' is 2
'E' - 'A' is 4

( 2 + 4 ) / 2 = 3

3 + 'A' is 'D'

Oddly enough...

C = 67 and E = 69...

67 + 69 = 136... 136/2 = 68

D is # 68 in the code.

So... 'C' <-> 'E' = 'D';

This is one case where conversion into and out of ASCII isn't required.