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God bless and keep you!
-Ginger

What do you want input from and what will you output to?

If you answer "keyboard" or "file" or similar to those questions, it follows that you would have to define "how to" access those. Which 'may' already be done for you in a library.

Hopefully some of the smart people can see beyond my thinking and really answer your question!

Look to Jesus,
Tim

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Called by God. The passioned plea of a father. The journey awaits at Jarod's Journey.

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God bless and keep you!
-Ginger

Also, yes, you're going to have to resort to assembly, at least inline assembly. Which technically means you're not doing it in C anyways, which again makes me wonder if the question is worded correctly. So not only does the hardware have to be defined before hand, but so does the compiler, because each compiler handles inline assembly differently.

So, assuming the question really means no standard C libraries, and you're on an x86 Intel system with a recent Microsoft compiler, I would use the various functions of DOS interrupt 21h and inline asm. Something like this (this is uncompiled code, and I haven't done this sort of thing in several years, so it probably won't even compile but hopefully it will at least point you in the right diretion):

int main() { char mychar; // char to receive keypress char message[100] = "Your key was: $"; char keymsg[10] = "x$"; __asm { mov ah, 1 ; function 01h = read keyboard int 21h ; call DOS interrupt 21h. Calling with ; function 01h will return the key character in AL. mov mychar, al ; save the contents of AL in our variable } // now output it to the screen __asm { mov ah, 8 ; function 08h = read keyboard without echo int 21h ; call DOS interrupt 21h. Calling with ; function 08h will return the key character in AL. mov mychar, al ; save the contents of AL in our variable } // save the keypress in the output string keymsg[0] = mychar; __asm { ; display the first part of the message mov dx, seg message ; make DS : DX point to message mov ds, dx mov dx, offset message mov ah,9 ; function 09h = write string ($ terminated) int 21h ; call DOS interrupt 21h ; display the second part of the message mov dx, seg keymsg ; make DS : DX point to keymsg mov ds, dx mov dx, offset keymsg mov ah,9 ; function 09h = write string ($ terminated) int 21h ; call DOS interrupt 21h } return 0; }

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[This message has been edited by BrianT (edited February 22, 2004).]

Write an optimized C program to convert a base 16 number to its base 10 equivalent, without using the standard C libraries, i.e. don’t use scanf(“%x”). The program should allow the user to input the number. State any assumptions you made when writing the program. Use 23DA as a test number.

I guess the assumptions they were talking about was the processor and compiler used, like you mentioned. Again, thank you! That was exactly what I needed to get unstuck. God bless you!

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God bless and keep you!
-Ginger

Ah, I think assembly may not be needed. The way the question is worded, I think it means you can't use libraries only for the conversion aspect - i.e. you can't use scanf("%x", &val), because %x is for hex values and would make conversion trivial (you'd just "printf("%d", val) and you're done). I'm wondering if the question means something like you can use scanf("%s", buffer) or gets(buffer) to read in input as a string (and then you assume it is a hex number, and then convert that to decimal using your conversion code (without using standard libraries) and then spit out the result with a simple printf("%d", val) . You should maybe ask your instructor for clarification if he means no standard libraries for the whole program, or just for the conversion.

If it's just for the conversion, you won't need assembly at all, and I can help you with that too (although I'll try not to do you're homework for you. )

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God bless and keep you!
-Ginger

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