C Reading list of numbers into multiple arrays - c

Question

So I am trying to write a program that prompts the user to input how many data sets the user wishes to have, aka how many arrays there are going to be. It then prompts the user to input how many values will be in each data set and what the values are. Finally it gives the user a list of options to run on a desired data set.
When I run my code and select which data set I want to use, it seems to always come up with the last data set and doesn't seem to have all of the values in the set. I was just wondering if someone could let me know what I'm doing wrong or at the very least put me on the right track. I've gone through the code multiple times and can't figure it out.
#include <stdio.h>
int main()
{
unsigned short int num_sets, set_size, set_desired, command = 0;
printf("Enter the number of data sets you would like to store: ");
scanf(" %hu", &num_sets);
int i = 1, j, sets[1][num_sets], sum, a;
while(i <= num_sets)
{
j = 1;
printf("Enter the number of elements in data set %hu: ", i);
scanf(" %hu", &set_size);
printf("Enter the data for set %hu: ", i);
while(j < set_size)
{
scanf(" %d", &sets[i - 1][j - 1]);
j++;
}
i++;
}
printf("Which set would you like to use?: ");
scanf(" %hu", &set_desired);
while(set_desired > num_sets){
printf("There aren't that many data sets, try again: ");
scanf(" %hu", &set_desired);
}
printf("Set #%hu: %hu\n", num_sets, *sets[num_sets - 1]);
while(command != 7){
printf("Choose what you would like to do:\n");
printf("1. Find the minimum value.\n");
printf("2. Find the maximum value.\n");
printf("3. Calculate the sum of all the values.\n");
printf("4. Calculate the average of all the values.\n");
printf("5. Sort the values in ascending order.\n");
printf("6. Select a different data set.\n");
printf("7. Exit the program.\n");
scanf(" %hu", &command);
if(command == 1){
printf("You picked 1!");
}
if(command == 2){
printf("You picked 2!");
}
if(command == 3){
/*printf("You picked 3!");
for(a = 0; a < set_size; a++){
sum = sum + *sets[a];
}
printf("%d\n", sum);*/
printf("You picked 3!");
}
if(command == 4){
printf("You picked 4!");
}
if(command == 5){
printf("You picked 5!");
}
if(command == 6){
printf("You picked 6!");
}
if(command == 7){
break;
}
}
}

Answer 1

If you are trying to store values in different sets than you need to maintain the number of items in each set separately as you don't know how many elements are there is each set.
The design should be such that:
Set 1 : Number of Elements : Actual values in the array.(Here I am storing the number of items in the set as part of the same array. It will be the first element in each set)
The memory allocation can be done dynamically as you are giving the option to the user to set the number of items per set.
#include <stdio.h>
#include<stdlib.h>
int main()
{
unsigned short int num_sets, set_size, set_desired, command = 0;
printf("Enter the number of data sets you would like to store: \n");
scanf(" %hu", &num_sets);
int *sets[num_sets];
int i = 0, k=0,j,sum, a;
while(i < num_sets)
{
j = 1;
printf("Enter the number of elements in data set %hu: \n", i+1);
scanf(" %hu", &set_size);
sets[i] = (int *) malloc((sizeof(int)*set_size));
*sets[i] = set_size;
printf("Enter the values for set %hu\n", i+1);
while(j <= set_size)
{
scanf(" %d", &sets[i][j]);
j++;
}
i++;
}
printf("Which set would you like to use?: \n");
scanf(" %hu", &set_desired);
while(set_desired > num_sets){
printf("There aren't that many data sets, try again: \n");
scanf(" %hu", &set_desired);
}
for(k=1;k<=(*sets[set_desired-1]);k++)
{
printf("Set #%hu: %hu \n", set_desired, *(sets[set_desired-1] + k));
}
while(command != 7){
printf("Choose what you would like to do:\n");
printf("1. Find the minimum value.\n");
printf("2. Find the maximum value.\n");
printf("3. Calculate the sum of all the values.\n");
printf("4. Calculate the average of all the values.\n");
printf("5. Sort the values in ascending order.\n");
printf("6. Select a different data set.\n");
printf("7. Exit the program.\n");
scanf(" %hu", &command);
if(command == 1){
printf("You picked 1!");
}
if(command == 2){
printf("You picked 2!");
}
if(command == 3){
/*printf("You picked 3!");
* for(a = 0; a < set_size; a++){
* sum = sum + *sets[a];
* }
* printf("%d\n", sum);*/
printf("You picked 3!");
}
if(command == 4){
printf("You picked 4!");
}
if(command == 5){
printf("You picked 5!");
}
if(command == 6){
printf("You picked 6!");
}
if(command == 7){
break;
}
}
return 0;
}

Answer 2

You have undefined behaviour in your code. In this line:
int i = 1, j, sets[1][num_sets], sum, a;
you allocate enough space for one element in each of num_sets sets of data. This isn't really what you need. You probably want the num_sets as the first index, and you need a larger value for the other index.
You are likely to need to do dynamic memory allocation. Failing that, you'll need to set an upper bound (maybe 100) on the size of the arrays, and reject attempts to create bigger arrays. You'd then use:
enum { MAX_ARR_SIZE = 100 };
int sets[num_sets][MAX_ARR_SIZE];
for the variable. Your data entry loop already assumes this method of indexing. You probably need to keep a record of how many entries there are in each row somewhere, so as to avoid using uninitialized data.
int set_size[num_sets];