How to select multiple elements in an array with C? - c

Question

Is there a way to select multiple elements in array using one line of code in C? For instance, say I had the following code (assuming I already asked the user for twenty numbers, the first ten I asked to be positive and the last ten I asked to be negative):
if (myArray[0 through 9] > 0)
{
printf("Thank you for providing positive numbers!");
}
else
{
printf("Sorry, please try again!");
}
if (myArray[10 through 19] < 0)
{
printf("Thank you for providing negative numbers!");
}
else
{
printf("Sorry, please try again!");
}
What code could I substitute for "through"? I am fairly new to this language, and have never heard of a way of doing so. I know that with this particular code I could make two arrays, one for the positive numbers and one for the negative numbers, but I am curious to know for other programming projects.
Thank you for reading and answering!

Answer 1

There's nothing built-in that does it, you need to write a loop. Don't forget that array indexes start at 0.
int all_positive = 1;
int i;
for (i = 0; i < 10; i++) {
if (myArray[i] <= 0) {
all_positive = 0;
break;
}
}
if (all_positive) {
printf("Thank you for providing positive numbers!\n");
}

Answer 2

int a[20];
// entering values for the array
_Bool first_positive = 1;
for ( size_t i = 0; i < 10 && first_positive; i++ )
{
first_positive = 0 < a[i];
}
if ( first_positive ) puts( "Hura, first 10 elements are positive" );
_Bool last_negative = 1;
for ( size_t i = 10; i < 20 && last_negative; i++ )
{
last_negative = a[i] < 0;
}
if ( last_negative ) puts( "Hura, last 10 elements are negative" );
Instead of type name _Bool you can use type int if your compiler does not support _Bool

Answer 3

The program requests number of rows (1D array).
Then asks for 2 integers, whole numbers.
Then asks user to select 2 rows.
The sum of the 2 selected rows is then added.
#include <stdio.h>
int main ()
//1D_Array. Load Element and Add Sumline .
//KHO2016.no5. mingw (TDM-GCC-32) . c-ansi .
{
//declare
int a,b,c,d,e,sum1=0;
int array[50];
int i,j,elm1,elm2;
//valuate
printf ("Plot a number of elements [1 - 20]: ");
scanf ("%d",&a);
printf ("Plot a value : ");
scanf ("%d",&b);
printf ("Plot an increment value : ");
scanf ("%d",&c);
//calculate
{for (i<0;i<=a;i++)
{array[i] =(b+(++c)); // set value for variable [i], inside the array subscript. the vairable [i] must have an INT, and an increment to function !
sum1 = (sum1 + array[i]);
printf ("Row [%.2d] : %.2d + %.2d = %d\n",i,b,c,array[i]);}
printf ("\nSum total = %d\n",sum1);}
printf ("\nRow [%.2d] = %d\n",b,array[b]);
printf ("Row [%.2d] = %d\n",a,array[a]);
printf ("Select 2 Rows :\n");
scanf ("%d%d",&elm1,&elm2);
d=elm1;
e=elm2;
printf ("You selected Row [%.2d] = %d\n",d,array[d]);
printf ("You selected Row [%.2d] = %d\n",e,array[e]);
printf ("The sum of two selected Rows [%d]+[%d] : %d + %d = %d\n",d,e,array[d],array[e],array[d]+array[e]);
//terminate
return 0;
}