C numeric code validator - c

Question

I'm new to C and programming in general, so I've studied a bit and wanted to make a simple program that validates personal numeric codes from my country. This is the program:
#include <stdio.h>
int validateCNP(char cnp[13]);
int main(int argc, const char * argv[])
{
char cnp[13];
printf("Introduceti CNP-ul:\n");
scanf("%s", cnp);
if(validateCNP(&cnp[0]) == 1) {
printf("CNP valid");
} else {
printf("CNP invalid");
}
return 0;
}
int validateCNP(char cnp[13]) {
char verif[13];
int intVerif[12], intCnp[13];
int i, checksum = 0;
strcpy(&verif[0], "279146358279");
for (i = 0; i<11; i++){
intVerif[i] = (unsigned)verif[i] - 48;
}
for (i=0; i<12; i++) {
intCnp[i] = cnp[i] - 48;
}
for (i=0; i<11; i++) {
checksum += intCnp[i] * intVerif[i];
}
checksum %= 11;
if (checksum == intCnp[12]) {
return 1;
} else {
return 0;
}
}
Sample output
Introduceti CNP-ul:
1650116398203
(lldb)
It also seems that when it converts strings to int arrays, it screws up the last element
Printing description of intVerif:
(int [12]) intVerif = {
[0] = 2
[1] = 7
[2] = 9
[3] = 1
[4] = 4
[5] = 6
[6] = 3
[7] = 5
[8] = 8
[9] = 2
[10] = 7
[11] = 32767
}
Printing description of intCnp:
(int [13]) intCnp = {
[0] = 1
[1] = 6
[2] = 5
[3] = 0
[4] = 1
[5] = 1
[6] = 6
[7] = 3
[8] = 9
[9] = 8
[10] = 2
[11] = 0
[12] = 0
}
Could someone point out what I'm doing wrong, I've tried different approaches, none seemed to work.

Answer 1

Your basic error was already pointed out by MadHatter: Your loops omit the last entry.
Another error is in main: The CNP is 13 characters long, so your cnp array must have at least 14 characters - you have to provide space for the terminating null character '\0'. You should also limit the length of the characters to read in oder to avoid buffer overflow:
scanf("%13s", cnp);
Here, the thirteen means that at most 13 characters (plus the terminating null character) are read.
It is a good idea to check whether your string actually has 13 digits, so that you don't process garbage characters. And you've forgotten to cater for the case where the remainder is 10 - in which case the check digit is 1.

Answer 2

You loop goes from 0 to 10:
for (i = 0; i<11; i++){
intVerif[i] = (unsigned)verif[i] - 48;
}
You are never writing intVerif[11] so it contains garbage.
Similar problem in intCnp[] also.
EDIT : (On OP's Comment)
Looks like your input:"1650116398203" is 13 letters long whereas your cnp array needs one extra space for \0 character. Therfore your input is causing array-out-of-bounds which leads to the undefined behavior.