Remove unnecessary value entries from multidimensional array in c? - arrays

Question

Hi I am working with a scenario where user input multiple contiguous arrays of different lengths and I want to store these array for further use.
I am using multidimensional array for this purpose.
Here is the code :
#include <stdio.h>
int main()
{
int rows,cols;
printf("Enter the number of user input arrays ? ");
scanf("%d",&rows);
printf("Enter the maximum number of inputs in a single array ?"); //Need to remove these lines
scanf("%d", &cols); //Need to remove these lines if possible
int array[rows][cols];
for(int i=0;i<rows;i++)
{
for(int j=0;j<cols;j++)
{
array[i][j]=0;
}
}
for(int i=0;i<rows;i++)
{
int count;
printf("Enter the number of inputs for array %d - ", i);
scanf("%d",&count);
for(int j=0;j<count;j++)
{
scanf("%d",&array[i][j]);
}
}
//// Use array for other purpose
////printf("\n\nArray --> \n");
////for(int i=0;i<rows;i++)
////{
////for(int j=0;j<cols;j++)
////{
////printf("%d ",array[i][j]);
////}
////printf("\n");
////}
return 0;
}
Example input :
Enter the number of user input arrays ? 5
Enter the maximum number of inputs in a single array ?5
Enter the number of inputs for array 0 - 5
1 2 6 3 5
Enter the number of inputs for array 1 - 1
3
Enter the number of inputs for array 2 - 2
6 5
Enter the number of inputs for array 3 - 1
3
Enter the number of inputs for array 4 - 1
9
Array created in this case :
1 2 6 3 5
3 0 0 0 0
6 5 0 0 0
3 0 0 0 0
9 0 0 0 0
Now I have number of issues in this case :
I want to reduce the space being used by removing the unnecessary entries in the array.
I would not like to use '0' or any other integer to define an unnecessary entry as it is a valid input.
I would like to remove the line
printf("Enter the maximum number of inputs in a single array ?");
scanf("%d", &cols);
Can anyone provide me help to overcome these issues.

Answer 1

From the design criteria you have described:
Array with user determined number of rows.
Rows have differing lengths, also user determined.
Reduce the space being used. (space only for real inputs, no padding, or filler values.)
Array definition is created at run-time per user inputs, but is not required to change during same run-time session.
Note: One design criteria: //Need to remove these lines if possible is not included in this solution. Without a description of the desired method to instruct user, I do not know how to improve on the the user prompt method.
Jagged arrays may be what you are looking for. Following is a simple example directly from the link that incorporates dynamic memory allocation that can be adapted to the code you have already discussed:
int main()
{
int rows;
//Place you user input prompts and scans here
// User input number of Rows
int* jagged[2];//
// Allocate memory for elements in row 0
jagged[0] = malloc(sizeof(int) * 1);
// Allocate memory for elements in row 1
jagged[1] = malloc(sizeof(int) * 3);
// Array to hold the size of each row
int Size[2] = { 1, 3 }, k = 0, number = 100;
// User enters the numbers
for (int i = 0; i < 2; i++) {
int* p = jagged[i];
for (int j = 0; j < Size[k]; j++) {
*p = number++;
// move the pointer
p++;
}
k++;
}
k = 0;
// Display elements in Jagged array
for (int i = 0; i < 2; i++) {
int* p = jagged[i];
for (int j = 0; j < Size[k]; j++) {
printf("%d ", *p);
// move the pointer to the next element
p++;
}
printf("\n");
k++;
// move the pointer to the next row
jagged[i]++;
}
return 0;
}
This is the concept moved a little closer to what I think you want, adapted from the code above to accept user input similar to what your code does...
int main(int argc, char *argv[])
{
int rows = 0;
int cols = 0;
int i, j;
int number = 100;
printf("Enter the number of user input arrays ? ");
scanf("%d",&rows);
// n Rows
int* jagged[rows];
int Size[rows];//array to keep size if each array
for(i=0;i<rows;i++)
{
printf("Enter the maximum number of inputs for array[%d]: ", i);
scanf("%d", &cols); //Need to remove these lines if possible
// Allocate memory for elements in row 0
jagged[i] = malloc(sizeof(jagged[i]) * cols);
Size[i] = cols;//set size of nth array
}
// User enters the numbers (This is spoofed. You will need to code per comment below.
for (i = 0; i < rows; i++) {
int* p = jagged[i];
for (j = 0; j < Size[i]; j++) {
*p = number++; //Note, this is spoofing user input .
//actual user input would be done exactly as above
//with printf prompts and scans for value
// move the pointer
p++;
}
}
// Display elements in Jagged array
for (i = 0; i < rows; i++) {
int* p = jagged[i];
for (int j = 0; j < Size[i]; j++) {
printf("%d ", *p);
// move the pointer to the next element
p++;
}
printf("\n");
// move the pointer to the next row
jagged[i]++;
}
return 0;
}