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ok, i know that store data in arrays. for example int grades[5], but let's say i don't want to input all five yet, first input (90), then go back to menu, choose a subject(Science), and input (91), and return to menu again. How do i use a for loop to do this.
what code do you have so far?
Maybe something like this:
there's probably a much better way of doing that, but im bored and stupid so... did that answer your question? :)Code:void enter_grade(int subject, float grade);
int x=0;
for(;;)
{
int subject;
float grade;
printf("Enter subject:\n\t0.Science\n\t1.Social Studies\n:");
scanf("%d", &subject);
printf("Enter grade for subject: ");
scanf("%f", &grade);
enter_grade(subject, grade);
}
void enter_grade(int subject, float grade)
{
grades[subject][x] = grade;
x++;
}
You want a variable size matrix thats it? Well you will have to go memory allocating (dunno if I wrote it right please correct me if I'm wrong I'm lazy about look at a dictionary) it dinamical...
For reference:
ALLOC(3) Linux Programmer's Manual MALLOC(3)
NAME
calloc, malloc, free, realloc - Allocate and free dynamic
memory
SYNOPSIS
#include <stdlib.h>
void *calloc(size_t nmemb, size_t size);
void *malloc(size_t size);
void free(void *ptr);
void *realloc(void *ptr, size_t size);
DESCRIPTION
calloc() allocates memory for an array of nmemb elements
of size bytes each and returns a pointer to the allocated
memory. The memory is set to zero.
malloc() allocates size bytes and returns a pointer to the
allocated memory. The memory is not cleared.
free() frees the memory space pointed to by ptr, which
must have been returned by a previous call to malloc(),
calloc() or realloc(). Otherwise, or if free(ptr) has
already been called before, undefined behaviour occurs.
If ptr is NULL, no operation is performed.
realloc() changes the size of the memory block pointed to
by ptr to size bytes. The contents will be unchanged to
the minimum of the old and new sizes; newly allocated memI am silly
ory will be uninitialized. If ptr is NULL, the call is
equivalent to malloc(size); if size is equal to zero, the
call is equivalent to free(ptr). Unless ptr is NULL, it
must have been returned by an earlier call to malloc(),
calloc() or realloc().
RETURN VALUE
For calloc() and malloc(), the value returned is a pointer
to the allocated memory, which is suitably aligned for any
kind of variable, or NULL if the request fails.
free() returns no value.
realloc() returns a pointer to the newly allocated memory,
which is suitably aligned for any kind of variable and may
be different from ptr, or NULL if the request fails. If
size was equal to 0, either NULL or a pointer suitable to
be passed to free() is returned. If realloc() fails the
original block is left untouched - it is not freed or
moved.
CONFORMING TO
ANSI-C
SEE ALSO
brk(2), posix_memalign(3)
NOTES
The Unix98 standard requires malloc(), calloc(), and realI am silly
loc() to set errno to ENOMEM upon failure. Glibc assumes
that this is done (and the glibc versions of these rouI am silly
tines do this); if you use a private malloc implementation
that does not set errno, then certain library routines may
fail without having a reason in errno.
Crashes in malloc(), free() or realloc() are almost always
related to heap corruption, such as overflowing an alloI am silly
cated chunk or freeing the same pointer twice.
Recent versions of Linux libc (later than 5.4.23) and GNU
libc (2.x) include a malloc implementation which is tunI am silly
able via environment variables. When MALLOC_CHECK_ is
set, a special (less efficient) implementation is used
which is designed to be tolerant against simple errors,
such as double calls of free() with the same argument, or
overruns of a single byte (off-by-one bugs). Not all such
errors can be protected against, however, and memory leaks
can result. If MALLOC_CHECK_ is set to 0, any detected
heap corruption is silently ignored; if set to 1, a diagI am silly
nostic is printed on stderr; if set to 2, abort() is
called immediately. This can be useful because otherwise
a crash may happen much later, and the true cause for the
problem is then very hard to track down.
BUGS
By default, Linux follows an optimistic memory allocation
strategy. This means that when malloc() returns non-NULL
there is no guarantee that the memory really is available.
This is a really bad bug. In case it turns out that the
system is out of memory, one or more processes will be
killed by the infamous OOM killer. In case Linux is
employed under circumstances where it would be less desirI am silly
able to suddenly lose some randomly picked processes, and
moreover the kernel version is sufficiently recent, one
can switch off this overcommitting behavior using a comI am silly
mand like
# echo 2 > /proc/sys/vm/overcommit_memory
See also the kernel Documentation directory, files
vm/overcommit-accounting and sysctl/vm.txt.
So IMHO you should make a matrix of list heads for each subject and just go putting the grades there.
here is what i came up with, i can select menu, go to that option,back to menu, do something different, but can't get it to print out my array after all input has been stored. Any suggestions?
#include <stdio.h>
#define MAX 10
int num_books(int[],int );
void print_num_books(int [],int);
int main(void)
{
int stock_amt[MAX];
int n;
while(n!=11)
{
printf("\nPlease choose an option below by typing a number between 1 and 11.\n\n");
printf("1\tAutomobiles\n\n");
printf("2\tCookbooks\n\n");
printf("3\tGardening\n\n");
printf("4\tHistory\n\n");
printf("5\tMystery\n\n");
printf("6\tPlanets\n\n");
printf("7\tScience fiction\n\n");
printf("8\tSelf Help\n\n");
printf("9\tSports\n\n");
printf("10\tTravel\n\n");
printf("11\tExit program\n\n");
n=num_books(stock_amt,MAX);
print_num_books(stock_amt,n);
}
}
int num_books(int stock_amt[],int lim)
{
int index=0,n;
scanf("%d", &n);
if(n==1)
{
printf("How many automobiles will Perfect book carry?");
scanf("%d",&stock_amt[index]);
}
else if(n==2)
{
printf("How many cookbooks will Perfect book carry?");
scanf("%d",&stock_amt[index]);
}
if(n==3)
{
printf("How many gardening will Perfect book carry?");
scanf("%d",&stock_amt[index]);
}
else if(n==4)
{
printf("How many History will Perfect book carry?");
scanf("%d",&stock_amt[index]);
}
if(n==5)
{
printf("How many Mystery will Perfect book carry?");
scanf("%d",&stock_amt[index]);
}
else if(n==6)
{
printf("How many Planets will Perfect book carry?");
scanf("%d",&stock_amt[index]);
}
if(n==7)
{
printf("How many Science fiction will Perfect book carry?");
scanf("%d",&stock_amt[index]);
}
else if(n==8)
{
printf("How many Self Help will Perfect book carry?");
scanf("%d",&stock_amt[index]);
}
if(n==9)
{
printf("How many Sports will Perfect book carry?");
scanf("%d",&stock_amt[index]);
}
else if(n==10)
{
printf("How many Travel will Perfect book carry?");
scanf("%d",&stock_amt[index]);
}
else return(index);
}
void print_num_books(int stock_amt[],int n)
{
int index;
printf("\n***STOCK INVENTORY**\n\n");
for(index=0;index<n;index++){
printf("Amount is %d\n",stock_amt[index]);
}
}
Use this as a base to work from:
Code:#include <stdio.h>
#include <stdlib.h>
int main ( void )
{
int a[10];
int index = 0;
int i;
while ( index < 10 ) {
printf ( "1) Add a number\n2) Display numbers\n" );
printf ( "Selection: " );
fflush ( stdout );
switch ( getchar() ) {
case '1':
printf ( "Enter a number: " );
fflush ( stdout );
if ( scanf ( "%d", &a[index++] ) != 1 ) {
fprintf ( stderr, "Invalid input\n" );
return EXIT_FAILURE;
}
break;
case '2':
for ( i = 0; i < index; i++ )
printf ( "%d ", a[i] );
printf ( "\n" );
break;
default:
fprintf ( stderr, "Invalid selection\n" );
return EXIT_FAILURE;
}
getchar(); /* Eat the newline */
}
return EXIT_SUCCESS;
}
I haven't learned the switch case yet, so not allowed to use in program
then use if/else statements?
Oh? Phooey, I spent the last twenty minutes toying around with your program. Perhaps something like below will help anyway... just not today. At least you can test it for errors as I did not. :DQuote:
Originally Posted by sal817
Code:#include <stdio.h>
#include <string.h>
#define MAXB 10
const char *BOOKS[] = { "automobile", "cook", "gardening", "history",
"mystery", "planet", "science fiction", "self help",
"sports", "travel" };
int selectBook(void);
void printSck(int *);
int main(void)
{
char buf[BUFSIZ], *p;
int stockAmt[MAXB] = { 0 }; /* init stock */
int cIndex, sAmount;
while((cIndex = selectBook()) != 11)
{
cIndex -= 1;
printf("How many %s%s will Perfect Book carry: ",
BOOKS[cIndex], (cIndex == 1 ? "books" : " books"));
fgets(buf, sizeof buf, stdin);
if((p = strchr(buf, '\n')) != NULL)
*p = '\0';
if((sscanf(buf, "%d", &sAmount)) != 1)
fprintf(stderr, "Invalid amount detected - %s. Ignoring entry.\n\n", buf);
else
stockAmt[cIndex] = sAmount;
}
printSck(stockAmt);
puts("\nDone.\n");
while(getchar() != '\n'){}
return (0);
}
int selectBook(void)
{
char tmp[5];
int choice;
static char *message = "Please select a book below (1-11)\n\n"
" 1) Automobiles\n"
" 2) Cookbooks\n"
" 3) Gardening\n"
" 4) History\n"
" 5) Mystery\n"
" 6) Planets\n"
" 7) Science Fiction\n"
" 8) Self Help\n"
" 9) Sports\n"
"10) Travel\n"
"11) Exit Program\n\n-> ";
do
{
printf("%s", message);
fgets(tmp, sizeof tmp, stdin);
}while((sscanf(tmp, "%d", &choice)) != 1 || (choice < 1 || choice > 11));
puts("\n");
return (choice);
}
void printSck(int *tmp)
{
int i;
puts(" ---- Inventory ----\n");
for(i=0; i < MAXB; i++)
printf("%16s = %d\n", BOOKS[i], tmp[i]);
}
can't use pointer either,only array if else+while+for
i think i'm going the wrong way about doing this. Ok i want to ask the user to select option, store data in array, and ouput like this
Autombiles Amount is 200
Cookbooks Amount is 500
History Amount is 300
..... ............
etc.............
a array of 10;
somwhere in here i probably need a for loop
UGH!! I don't get this stuff!!!
please help!
1) Read the Announcements.
2) Use [code] tags. You'd know this if you'd done #1.
3) Write it out on paper, in big steps.
Once you have that done, you can breat it into smaller steps:Code:buy food:
go to the store
pick out things I need
pay for them
come home
Quzah.Code:go to store:
leave house
walk or use some form of transportation
pick out things I need:
...
Your algorithm will depend on how you want the user to input information - sequentially or random. If you simply want the user to input values for each book one at a time, then use a for loop starting at pos 0, and ending at pos MAX - 1. However, if you want to bounce around with the input order, then I'd go with a while loop... something like:Quote:
Originally Posted by sal817
If you initialize your array to some value that your cannot enter, then you can use that known value to display only the books that have a good value in them.Code:while((index = getBookRequest()) != quit_program)
{
bookArray[index] = getInventoryAmount(BOOKS[index]);
/* other stuff */
}
int getInventoryAmount(const char theBook[])
{
int value;
printf("How many %s books to add: ", theBook);
scanf(" %d", &value);
return (value);
}
For this to work, BOOKS can be made a const globalCode:int showInventory(int myArray[])
{
int i;
for(i =0; i < MAX; i++)
{
if(myArray[i] != known value)
printf("%s amount %d\n", BOOKS[i], myArray[i]);
}
}
const char BOOKS[][MAXLEN] = { "...", "...", ... };
As mentioned before by Prelude, check the status of all calls to scanf. If you're going to read numbers directly, then you'll want to make certain that you don't wind up with stream errors.
HTH
ok i work on list last night, and still having problems, How do i get from menu to the function(error--category does not return a function) I want to be able to store the option, and go through menu, till hits 10. I've been on this too long!!
Please help!!
#include <stdio.h>
int category(int[10],int[10],float[10],int[10]);
int main(void)
{
int n;
while(n!=11)
{
printf("\nPlease choose an option below by typing a number between 1 and 11.\n\n");
printf("1\tAutomobiles\n\n");
printf("2\tCookbooks\n\n");
printf("3\tGardening\n\n");
printf("4\tHistory\n\n");
printf("5\tMystery\n\n");
printf("6\tPlanets\n\n");
printf("7\tScience fiction\n\n");
printf("8\tSelf Help\n\n");
printf("9\tSports\n\n");
printf("10\tTravel\n\n");
printf("11\tExit program\n\n");
scanf("%d",&n);
n=category();
}
return(n);
}
int category(int list[],int stock_amt[],float avg_price[],int sell_percentage[])
{
int i=0;
printf("Enter category number(0 to end): ");
scanf("%d",&list[i]);
while(list[i]!=0)
{
printf("How many books will Perfect book carry?");
scanf("%d",&stock_amt[i]);
printf("What is the avg price for book?");
scanf("%f",&avg_price[i]);
printf("What is the selling percentage for book?");
scanf("%d",&sell_percentage[i]);
i++;
}
return(i);
}
It sounds like you're after a 2D array, where your book categories have three properties each. For example, the user loops through each of the 10 book categories inserting values into each of the three properties.Quote:
Originally Posted by sal817
I still don't quite understand what you're after as your code doesn't equate to your description.
However, you can try something like:
Code:
#define MAXS 10
void category(int, char [], int[], float[], int[]);
...
/* declare these in main */
char books[MAXS][18] = { "automobile", ... "travel" };
int i, count, stock_amt[MAXS], sell_p[MAXS];
float ave_price[MAXS];
count=0;
while(count < MAXS)
{
prompt for category number
read in category number (var i)
validate range of number
if i holds the exit value then
set count to MAXS
else
{
check number arrays for [i] having data already
if(any number_array[i] == init_value)
{
category(i, books[i], stock_amt, ave_price, sell_p);
count++;
}
}
}
...
void category(int index, char thebook[], int s[], float a[], int p[])
{
printf("How many %s books will ....", thebook);
scanf(" %d", &s[index]);
printf("What is the average price for %s books: ", thebook);
scanf(" %f", &a[index]);
....
}
I've already said this once, and it's starting to get repetitive: USE [CODE] TAGS!
Quzah.
Ronin,
Is what i want to do, to
1.get the number of books in stock for each category
2. go through category(1) and get the avg price
3.go through category(1) and get sell percentage
so that I'll get this when i printout
Category Stock Avg_Price Sell_Percent
Cookbooks 100 11.25 25
History 250 9.99 35
......... ...... ........ ......
......... ....... .......... .......
Max[10] >>>> >>>>> >>>>
does this help any?
Any one please help me?
Down to the last wire?
I *thought* I did that already. :D
Consider:
You can play around with that, and see if it will help you... dunno how many bugs it has though. Use at your own risk!Code:
#include <stdio.h>
#define MAXB 5
const char BOOKS[][18] = { "Automobile", "Cook",
"Gardening", "History",
"Mystery" };
int getIndex(void);
void requestInput(int, int [], int [], float []);
void pushData(int [], int [], float [], int []);
int main(void)
{
int index, done, invt[MAXB],
sellp[MAXB],
check[MAXB] = { 0 };
float avep[MAXB];
done = 0;
while(done < MAXB)
{
index = getIndex() - 1;
if(index == 5)
done = MAXB;
else
{
if(check[index] == 0)
{
requestInput(index, invt, sellp, avep);
check[index] = 1;
done++;
}
else
puts("\nContains data already.\n");
}
}
pushData(invt, sellp, avep, check);
puts("\nDone.");
return (0);
}
int getIndex(void)
{
int i;
static char myprompt[] = "1) Automobile\n2) Cook\n3) Garden\n"
"4) History\n5) Mystery\n6) Quit\n\n--> ";
do
{
fflush(stdout);
puts("\nSelect a book category (1-6) \n");
printf("%s", myprompt);
scanf(" %d", &i);
}while(i < 1 || i > 6);
return (i);
}
void requestInput(int i, int a[], int b[], float c[])
{
printf("\nEnter number of %s books: ", BOOKS[i]);
scanf(" %d", &a[i]);
printf("Enter the sell percentage of %s books: ", BOOKS[i]);
scanf( "%d", &b[i]);
printf("Enter the ave price for %s books: ", BOOKS[i]);
scanf(" %f", &c[i]);
}
void pushData(int a[], int b[], float c[], int d[])
{
int i;
puts("\nCategory Stock Avg_Price Sell_Percent\n");
for(i=0; i < MAXB; i++)
{
if(d[i] == 1)
printf("%s\t%d\t%.2f\t%d\n", BOOKS[i], a[i], c[i], b[i]);
}
}