How to assign first element in array to a variable?

Question

I'm new to c and I have trouble with arrays in c. I don't know how to assign first element from an array to an int variable. When I tried, I got a random large integer from nowhere even index was in range.

This is part of my code:

int solve(int *elev, int n)
{
    for (int i = 0; i < n; ++i)
        printf("%d ", elev[i]);
    putchar('\n');

    printf("%d %d %d %d %d\n", elev[0], elev[1], elev[2], elev[3], elev[4]);

    int low = elev[0];
    int high = elev[4];

    printf("low:%d high:%d\n");

    // ...
}

Partial output:

1 4 20 21 24
1 4 20 21 24
low: 362452 high: 7897346

What was a cause of above output?

In addition to Dacre's answer, I'd rid the 2nd printf statement in favor of the dynamic for-loop---assuming you were just testing? And high is likely to be elev[n-1] (assuming n>0 and elev[] is sorted) — Rafael
– Rafael, Commented Nov 6, 2018 at 2:54

Dacre Denny · Accepted Answer · 2018-11-06 20:34:00Z

4

It looks like you're not passing the low or high variables as arguments to the printf() call, on this line:

printf("low:%d high:%d\n")

If you provide the low and high variables as arguments to printf() then the expected output should be printed to the console, like so:

printf("low:%d high:%d\n", low, high);

The "print format" of "low:%d high:%d\n" being passed to the printf() function states that number values will be displayed for each occurrence of %d in the format string.

In order to specify the actual values that will be displayed for each occurrence of %d, additional arguments must be provided to the printf() function - one for each occurrence of %d:

printf("low:%d high:%d\n", 
low, /* <- the value of low will be printed after "low:" in output the string */
high /* <- the value of low will be printed after "low:" in output the string */
);

If these additional arguments are not provided, the program will still compile and run however, at run-time, the program will basically display what ever value is found at the memory locations where it expected to find values for each of the %d occurrences.

For more information on printf(), you might like to see this documentation - hope this helps!

edited Nov 6, 2018 at 20:34

answered Nov 6, 2018 at 2:44

Dacre Denny

30.4k5 gold badges53 silver badges66 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Dacre Denny Over a year ago

@Yunnosch thanks for the feedback! - just updated the answer, what do you think? :-)

Collectives™ on Stack Overflow

How to assign first element in array to a variable?

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related