Thread: arrays on c

hello guys i have read the c primer plus 5th edition by stephen prata and he give a problem exercises on chapter 10 about arrays and function on no. 6 problem i don't know how to do it....because he says that you can copy a 2 array with a 1 array function....can some please teach how to do it...or for further info..read the "c primer plus"thanks

Consider an M by N array an array with M * N elements.

i think i didn't make my questions clear..... Here's the question in chapter 10..problem 2....
Problem 2:
Write a program that initializes an array-of-double and then copies the contents of the array into two other arrays. (All three arrays should be declared in the main program.) To make the first copy, use a function with array notation. To make the second copy, use a function with pointer notation and pointer incrementing. Have each function take as arguments the name of the target array and the number of elements to be copied. That is, the function calls would look like this, given the following declarations:

Code:

double source[5] = {1.1, 2.2, 3.3., 4.4, 5.5};
double target1[5];
double target2[5];
copy_arr(source, target1, 5);
copy_ptr(source, target1, 5);

-------
and here's my answer to that problem...

Code:

#include <stdio.h>
void show(double *,int);
void copy_ptr(double *, double *, int);
void copy_arr(double [],double [], int);
int main(void)
{
    double source[5] = {1.1, 2.2, 3.3, 4.4, 5.5};
    double target1[5];
    double target2[5];
    copy_arr(source,target1,5);
    copy_ptr(source, target1, 5);
    show(source,5);
    show(target1,5);
    show(target1,5);
    return 0;
}
void copy_arr(double ar[],double b[], int a)
{
     int c;
     for(c=0;c<a;c++)
     b[c]=ar[c];
}
void copy_ptr(double *ar, double *b, int a)
{
     int c;
     for(c=0;c<a;c++)
     *(ar+c)=*(b+c);
}
void show(double *ar, int a)
{
     int c;
     for(c=0;c<a;c++)
     printf("&#37;g\t",*(ar+c));
     printf("\n");
}

-------
no problem in that question...it is very simple...but on problem 6....here it goes
Write a program that initializes a two-dimensional array-of-double and uses one of the copy functions from exercise 2 to copy it to a second two-dimensional array. (Because a two-dimensional array is an array of arrays, a one-dimensional copy function can be used with each subarray.)

to use one of the function of my answer in problem 2....like for example this kind of function that i've arrived in problem 2....
-------------

Code:

void copy_arr(double ar[][], double *, int);

<---in this line i change the 1st argument because we gonna pass a 2-dimensional array....but it would error in the 2nd argument because of the compiler warning...saying that the argument is not right to pass an 2-dimensional array on a 1 dimensional array......did you get my question???thnx for replying

Hey guys do u know a way I can capitalize everything writen in a specific type of char array?...For example:

Code:

typedef char Str[50]; //I want everything in this array to be TOUPPERed

typedef struct {
	Str title, director, genre, year, available, code; // all will be in a struct
	}MOVIE;

I couldn't manage to make common toupper when I read them... the following allways shows an error: "request for member `title' in something not a structure or union"

Code:

void movielist (MOVIE list[50]){
    
	puts("Type in the movie Title:");
	gets((*list).title);
                list.title=toupper(list.title);   
}

Isn't there a way I could allready toupper as soon as I declared my Str[50] or even the struct MOVIE?

4x3:

[0x0][0x1][0x2][1x0][1x1][1x2][2x0][2x1][2x2][3x0][3x1][3x2]

12 element array:

[0][1]2][3][4][5][6][7][8][9][10][11]

4x3 as 12 element array

[0x0][0x1][0x2][0x3][0x4][0x5][0x6][0x7][0x8][0x9][0x10][0x11]

4 * 3 = 12

Originally Posted by Nagash

Hey guys do u know a way I can capitalize everything writen in a specific type of char array?...For example:

Code:

typedef char Str[50]; //I want everything in this array to be TOUPPERed

typedef struct {
	Str title, director, genre, year, available, code; // all will be in a struct
	}MOVIE;

I couldn't manage to make common toupper when I read them... the following allways shows an error: "request for member `title' in something not a structure or union"

Code:

void movielist (MOVIE list[50]){
    
	puts("Type in the movie Title:");
	gets((*list).title);
                list.title=toupper(list.title);   
}

Isn't there a way I could allready toupper as soon as I declared my Str[50] or even the struct MOVIE?

toupper works on a character-by-character basis, not on a string as a whole. So you would have to go through your title character-by-character and toupper each character.

Just compile my sig to see what Elysia is talking about. And as an extra added bonus, when it prompts you for user input, type in something like:

I like getting 100&#37;s better than 50%s on my tests.

Code:

void copy_arr(double ar[],double b[], int a)
{
     int c;
     for(c=0;c<a;c++)
     b[c]=ar[c]; // You failed to indent here
}

i don't get it elysia.....as far as i know my codes are 100% working...this is just a sample of my answer in problem 2....

Code:

void copy_ptr(double *ar, double *b, int a)
{
     int c;
     for(c=0;c<a;c++)
     *(ar+c)=*(b+c); // This is wrong. You were supposed to increment the pointer! You also forgot to indent.
}

and you're correction about the pointer...that is the pointer that i am incrementing....
it goes like this right...

Code:

int ar[5]; \\an array of 5 1d array
int *ptr; \\a pointer
ptr=ar; \\assigning the address of the ar to the ptr....
so if you would like to access the 2nd element you would have to increment the pointer right....
then here it is....
*(ptr+1) \\since 0 is the 1st element then we add 1 to get to the 2nd element....

yah...i got the description but it would make a compiler error....compile it to belief it..that's why i am posting it here so that i could find the answer....btw thanks for you're effort

Example:

Code:

void copy_ptr(double *ar, double *b, int a)
{
     double *end = ar + a;

     for(;ar < end;)
         *ar++=*b++;
}

Is what I believe she is telling you to do.

You may also wish to double check the parameters to make sure they are not NULL.

Well handing out solutions is my middle name. I had it legally changed back in 2006 after a mishap in Mexico. I was going to change the code to psuedo code to appease your perfectly valid point, however its hard to make this particular concept into psuedo code...