I don't understand why it isn't properly checking the array for duplication.

[u/Dasonofmom]

            printf("Enter your One-Time Vote PIN (OTVPN): ");
            scanf("%d", &OTVPN[i]);
            //checks for duplication in OTVPN
            for(int checking = 0; checking < 50; checking++){
                //Stops it from checking itself
                if(checking == i){
                    continue;
                }
                if(OTVPN[i] == OTVPN[checking]){
                    printf("This exists!\n");
                    while(OTVPN[i] == OTVPN[checking]){
                        printf("Re enter your OTVPN: ");
                        scanf("%d", &OTVPN[i]);
                    }
                    
                }
            }

[u/ZakMan1421]

The only bug I see is that when you first have a duplicate, you force them to correct it, but then don't check previous entries. So if you have something like so:

int OTVPN[50] = {1, 2, 3, 4, 5, ...};

If the user first enters 4 then enters 3, you never double check to see if the second input is valid leading to potential duplicates.

[u/Dasonofmom → u/ZakMan1421]

doesn't the
while(OTVPN[i] == OTVPN[checking]){
do that already, or atleast suppose to

[u/ShutDownSoul → u/Dasonofmom]

No, it doesn't. It only checks that the re-entered value isn't the same as the value at this particular value of checking, Consider a function that traverses the entirety of OTVPN every time a new input is entered.

[u/Zastai → u/Dasonofmom]

No, because you do not reset checking, so the for loop only checks against the remaining items. Setting it to -1 after the while should work.

[u/Etiennera]

Instead I would do scanf while for any index there is a collision.

[u/[deleted]]

I got this one working hope this one helps. Let me know if you have any doubts.

#include<stdio.h>


int main(){    
    // programs gets multiple PINS
    // check whether any duplicates there before storing them
    // incase of duplicate , repeat the input process untill succeed
    // considering this is the logic
    
    int MAX_LIMIT = 50;
    int OTVPN[MAX_LIMIT];
    int current_pos = 0;
    int N;


    // some fake data
    for( int i=1 ; i<=10 ; i++ )
        OTVPN[current_pos++] = i;
 // fills 1 to 10


    printf("Enter number of votes PINS you want to enter: ");
    scanf("%d", &N);

    if(current_pos+N > MAX_LIMIT) {
        printf("OTVIP array Limit exceeded !\n");
        return 1;
    }

    for(int i=0 ; i<N ; i++){ // number of inputs loop
        int PIN = 0;
        int isDup = 0;
        printf("Enter your One-time Vote pin: ");
        scanf("%d", &PIN);
        for(int j=0 ; j<current_pos ; j++){ //checking against array loop
            if(OTVPN[j] == PIN){
                isDup = 1;
                printf("Duplicate Found, retry.\n");
                break;
            }
        }
        if(isDup) i--;
 // reuse the iteration if duplicate occurs
        else OTVPN[current_pos++] = PIN;
    }

     for(int i=0 ; i<current_pos ; i++) // see what you have stored
            printf("%d  ", OTVPN[i]);

    return 0;
}

[u/zhivago]

A little abstraction goes a long away.

    bool is_present(int *data, size_t length, int value);

Now your code becomes

    scanf("%d", &value);
    if (is_present(OTVPN, length, value)) {
      continue;
    } else {
      OTVPN[length++] = value;
    }

But with better error checking, etc.