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#include <iostream.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
void condition(char seat, char pos, char object) {
printf("Toilet seat is %c and you are %c. There is %c on the seat. \n", seat, pos, object);
}
void input(char seat, char pos, char object) {
scanf("What do you want to do? \n", &seat, &pos, &object);
}
int main()
{
char seat[10];
char pos[10];
char object [10];
call(input);
call(condition);
return 0;
}
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// #include <iostream.h> -- don't need this
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
// these parameters need to be character pointers
void condition(char* seat, char* pos, char* object)
{
// %c prints out 1 character -- you want %s, which
// prints out an entire string
printf("Toilet seat is %s and you are %s. "
"There is %s on the seat. \n", seat, pos, object);
}
void input(char* seat, char* pos, char* object)
{
// this works on Visual C++ 6.0
printf("What do you want to do?\n");
// don't think this is especially good practice
// (it's not very fault-tolerant), but it works
// if you do the input right
scanf("%s", seat);
scanf("%s", pos);
scanf("%s", object);
}
int main()
{
char seat[10];
char pos[10];
char object [10];
// the seat, pos, and object here are not the
// same seat, pos, and object that are in the
// input function
input(seat, pos, object);
// same goes for the condition function
condition(seat, pos, object);
return 0;
}
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int i;
int *p;
i = 42;
p = &i; // the ampersand means 'return this variables address'
. If you can get Assembly Language Step by Step, then learning assembly first wouldn't be a bad idea, either.The specific problem is in the code Joel wrote for calling the functions:Kon-Tiki wrote: Ok, that works now, but the output gives weird ascii-codes. This's with converting and reconverting, IIRC, but dunno how to go against it. Oh well, I'll follow Tim's advice and start reading from the moment I know that I won't waste my time on the book I have. Maybe I'll be able to figure it out then.
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input(seat, pos, object);
// same goes for the condition function
condition(seat, pos, object);
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input(&seat, &pos, &object);
// same goes for the condition function
condition(&seat, &pos, &object);
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char seat[10];
// this is valid
char* p1 = seat;
// so is this
char* p2 = &seat[0];
// this is not
char* p3 = &seat;
// although I'm not really sure why it wouldn't be
// since the following expression is true
reinterpret_cast<void*>(seat) ==
reinterpret_cast<void*>(&seat);
// Visual C++ considers &seat to be an expression
// of type char (*)[10] -- which it considers distinct
// from char*
Interesting. You were right; I tested your code under Dev-C++, and it worked as written, while adding the address-of operator does indeed cause a compile error. I'll have to check my references and see what I've misunderstood. Thank you for pointing this out.Joel wrote: in C++ you can write the code exactly as I wrote it and it works fine. As I said, I tested it in Visual C++ prior to copying and pasting it directly to the board. Putting the address-of operator in front of the array names prevents the program from compiling.
So apparently, while I was right about how array identifiers differ from pointers to arrays (I think), I had misunderstood the actual behavior in code. I'll chalk it up to a learning experience. Again, Joel, thank you for pointing my mistake out.C provides a shorthand for dealing with arrays. Rather than writing:
[tt]array_ptr = &array[[0]];[/tt]
we can write
[tt]array_ptr = array;[/tt]
C blurs the distinction between pointers and arrays by treating them in the same manner in many cases. Here we use the variable [tt]array[/tt] as a pointer, and C automatically does the necessary conversion.
