For 循环 - 输出比需要的多

Question

Well all I had to do was:

• user has to enter 20 numbers.
• and I should find from array numbers lower than the last number user entered ( 20 numbers )

Example :

User enters:

1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,4

Output should be:

1,2,3

according to me, my output is correct. But after 1,2,3 alot of 0 come in.

#include <iostream>
using namespace std;
int i,skaitlis,sk2,x;
int masivs[19];
int main() {


for ( i=0; i<=19; i++ )
{
   cin >> masivs[i];
   skaitlis = masivs[19];
}

for (i=0;i < sizeof masivs; i++){
    if ( masivs[i]<skaitlis){
        cout << masivs[i] <<endl;
    }
}

}

Answer 1

The problem is here:

for (i=0;i < sizeof masivs; i++){

The sizeof operator returns the size of the array in bytes , not in number of elements. On normal modern systems the size of an int is four bytes, meaning sizeof masivs will give you 4*19 .

That will lead the loop going massively out of bounds and give you undefined behavior .

Not to mention the other out of bounds you have in the previous loop.

Also, taking about the first loop, why have the assignment to skaitlis inside the loop? After you fix the out-of-bounds indexing, it will just assign zero (because masivs is a global variable and therefore initialized to all zeroes) except in the last iteration. You can move that assignment to be outside the loop.