how can I make a loop print out missing elements in my int array?

Question

I've been trying to solve an assignment where you:

1. Enter the size N of an array of ints
2. Enter the max value M of the ints that you want to populate the array with
3. Enter N values that are of a value between 1 and M, into a second array.
4. compare these two and print out the missing numbers...

Like this:

Size of array? 10 // => N = 10
Max value in array? 8 // => M = 8
Please enter 10 values between 1 and 8:
4 1 3 1 7 3 4 4 6 1
Missing values: 2 5 8

for some reason, my for loop just prints out all the numbers between 1 and M instead, no matter what I try... What am I missing??

code:

#include <stdio.h>
int main(void)
{
 int aSize, mValue;
 printf("Size of array? ");
 scanf(" %d", &aSize);
 printf("Max value in array: ");
 scanf(" %d", &mValue);
 int table[aSize];
 int values[mValue];
 for (int i = 0; i < aSize; i++)
 {
 table[i] = i+1;
 if ((i+1) > mValue)
 {
 table[i] = 0;
 }
 }
 printf("Please enter %d values between 1 and %d:\n", aSize, mValue);
 for (int i = 0; i < mValue; i++)
 {
 scanf(" %d", &values[i]);
 }
 for(int i = 0; i < aSize; i++)
 {
 for (int j = 0; j < mValue; j++)
 {
 if(table[i] != values[j] && table[i] != 0)
 {
 printf("%d ", table[i]);
 break;
 }
 }
 }
}

• Some programmer dude: My method would be something like this: Get input; Sort the array; Loop over the array, if the difference between the previous value (initialized to 0) and the current value is larger than 1 then there's a value missing; Save the current value as the previous value; Iterate the loop.
• pmg: You want the array values (and, of course, also the array table) to have space for N elements, not M elements as in your code.

Answer 1

#include <stdio.h>
 int main()
 {
 int aSize, mValue;
 printf("Size of array? ");
 scanf(" %d", &aSize);
 printf("Max value in array: ");
 scanf(" %d", &mValue);
 int table[aSize];
 int values[aSize]; // not 'mSize' because it is just max value not size of array
 for (int i = 0; i < aSize; i++)
 {
 table[i] = i+1;
 if ((i+1) > mValue)
 {
 table[i] = 0;
 }
 }
 printf("Please enter %d values between 1 and %d:\n", aSize, mValue);
 for (int i = 0; i < aSize; i++)
 {
 scanf(" %d", &values[i]);
 }
 for(int i = 0; i < aSize; i++)
 {
 int flag=0;
 for (int j = 0; j < aSize; j++)
 {
 if(table[i] == 0 || table[i] == values[j]) // numbers in common or zero
 {
 flag=1;
 break;
 }
 }
 if(flag == 0) printf("%d",table[i]); // missing numbers
 }
}

Answer 2

In this code, I'm creating an extra array to store the occurance of the variable, then printing it. 1 means present 0 means not present.

#include <stdio.h>
int main(void) {
 int aSize, mValue;
 printf("Size of array? ");
 scanf(" %d", &aSize);
 printf("Max value in array: ");
 scanf(" %d", &mValue);
 int table[aSize];
 int values[mValue+1];
 for (int i = 0; i <= mValue; i++)
 {
 values[i]=0;
 }
 values[0]=1;
 printf("Please enter %d values between 1 and %d:\n", aSize, mValue);
 for (int i = 0; i < aSize; i++)
 {
 scanf(" %d", &table[i]);
 if(table[i]>mValue || table[i]<1){
 printf("Enter numbers in given range");
 return 0;
 }
 }
 for(int i = 0; i < aSize; i++)
 {
 values[table[i]]=1;
 }
 printf("Missing values:\n");
 for(int i = 1; i <= mValue; i++)
 {
 if(!values[i])
 printf("%d\n",i);
 }
 return 0;
}

This is better version of the above logic.

#include <stdio.h>
int main(void) {
 int aSize, mValue;
 printf("Size of array? ");
 scanf(" %d", &aSize);
 printf("Max value in array: ");
 scanf(" %d", &mValue);
 
 int temp;
 int values[mValue+1];
 values[0]=1;
 printf("Please enter %d values between 1 and %d:\n", aSize, mValue);
 for (int i = 0; i < aSize; i++)
 {
 scanf(" %d", &temp);
 if(temp>mValue || temp<1){
 printf("Enter numbers in given range");
 return 0;
 }
 values[temp]=1;
 }
 
 printf("Missing values:\n");
 for(int i = 1; i <= mValue; i++)
 {
 if(!values[i])
 printf("%d\n",i);
 }
 return 0;
}

• Dimitri Mikhalev: might be my brain is tired right now, but it feels a bit harder for me to understand this one... But I am sure that it is good :)
• Rapid: Try to dry run it, They both are time efficient. And second one is memory efficient also.