Why this program prints 0? - c

Question

I am supposed to write a program that prints the minimum value from vector.This is what i tried. It only prints 0. I tried to change the sign both ways but it doesnt work.
#include <stdio.h>
int read(int v[], int size)
{
int i = 0;
do
{
scanf("%i", &v[i]);
i++;
} while (v[i-1] != 0 && i < size);
int n = i;
return n;
}
int minim(int v[], int n)
{
int m;
m = v[0];
int i;
for (i = 1; i <= n-1; i++)
{
if (v[i] < m)
{
m = v[i];
}
}
return m;
}
int main()
{
int arr[100];
int n = read(arr, 100);
int min = minim(arr, n);
printf("\nMinimum vrom vector is %i\n", min);
return 0;
}

Answer 1

Since your scanf loop (I'd recommend staying away from function names like read, which are part of the C standard, even if you didn't include unistd.h) ends when 0 is entered, you need to include a check at the end to decrement the size of the array if 0 is the last entry. Basically, replace everything after your do-while loop with this:
if (v[i - 1]) {
return i;
}
return --i;
This will return i if all 100 elements are non-zero, otherwise it will decrement to remove the 0 from your array before returning. No need to declare int n=i just to instantly return n.
Edit: I saw your comment that it worked properly for finding the maximum. This is because you almost certainly entered a number into the array that's greater than 0, so adding 0 at the end would not affect the maximum number. Try finding the max again, but only enter negative numbers. The result will be 0.

Answer 2

read() uses a 0 entry to terminate reading more input. Yet that 0 is included in the array and counts toward the array length as part of the return value.
Instead, only increment the array count when input was numeric and non-zero.
int read(int v[], int size) {
int i = 0;
while (i < size) {
// Also test if valid numeric input was read.
if (scanf("%i", &v[i]) != 1) {
break;
}
// Stop if a 0 was read
if (v[i] == 0) {
break;
}
// Now increment
i++;
}
return i;
}
Could use shorter code, yet it is less readable. Best to code for clarity.
int read(int v[], int size) {
int i = 0;
while (i < size && scanf("%i", &v[i]) == 1 && v[i]) {
i++;
}
return i;
}

Answer 3

The test condition
while (v[i-1] != 0
checks whether the last element read was 0, after it was successfully processed and converted by scanf (but you never checked the return value). The 0 is then included in the array, and will always be the minimum unless you enter a non-negative number.
Here's the working code:
#include <stdio.h>
#include <stdlib.h>
static size_t read (int v[], size_t size)
{
size_t i = 0;
do
{
/* Check if scanf was successful */
if (scanf("%i",&v[i]) != 1) {
fprintf(stderr, "Error: Invalid input.\n");
return EXIT_FAILURE;
}
} while (v[i] != 0 && ++i < size);
return i;
}
static int minim (int v[],size_t n)
{
int min;
min = v[0];
for(size_t i = 1; i < n; i++) {
if (v[i] < min) {
min = v[i];
}
}
return min;
}
int main(void)
{
int arr[100];
size_t n = read(arr,100);
int min = minim(arr,n);
printf("\nMinimum vrom vector is %i\n", min);
return EXIT_SUCCESS;
}
I made some minor changes to it. Though I'm not satisfied with the design.
Sample I/O:
20
8
18
60
39
56
0
Minimum vrom vector is 8