#include<stdio.h>
#include<ctype.h>
void enter_num(char base_num[], int num);
int main()
{
char base_num[7] = {};
enter_num(base_num, 7);
printf("%c", base_num[1]);
return0;
}
void enter_num(char base_num[], int num)
{
int i;
for ( i = 0; i < num; i++)//for user input,stop when input is blank
{
base_num[i] = getchar();
if (isspace(base_num[i]))
{
base_num[i] = '\0';
}
if (isalnum(base_num[i])||base_num[i]=='\0')//Verify if the digital input is correct, if not, re-enter
;
else
{
printf("The number is wrong!Please enter again.\n");
i = 0;
}
if (base_num[i] = '\0')
{
break;
}
}
int n = 0;
while (n < i)//Convert all input letters to lowercase
{
if (isalpha(base_num[n]))
{
base_num[n] = tolower(base_num[n]);
}
n++;
}
}

What I have tried:

I tried to output the second array element, but I output blank space. And I need to output two line breaks to end the program.