Need some help for this C code

Question

I have even entered value even between 3 to 10 but same error. Need some help!

int main() {
    printf("\nPlease enter the number of days between 3 and 10, inclusive:\n");

    int high[10] = { 0 };
    int low[3] = { 0 };

    int i = 0;
    int days = 4;

    for (i = 0; i < days; i++) {

        do
        {
            if (i < 3 || i > 10) {
              printf("Invalid entry, please enter a number between 3 and 10, inclusive:");
            }
            printf(" \nDay %d - High: ", i + 1);
            scanf("%d", &high[i]);
            printf("Day %d - Low: ", i + 1);
            scanf("%d", &low[i]);
       } while (i < 3 || i > 10);
    }

Output Should be like this:

(Part A)

• Day 1 - High: 6
• Day 1 - Low: -2
• Day 2 - High: 8
• Day 2 - Low: -1
• Day 3 - High: 7
• Day 3 - Low: -3
• Day 4 - High: 9
• Day 4 - Low: -4

Other part of output: (Part B)

Enter a number between 1 and 4 to see the average temperature for the entered number of days, enter a negative number to exit: 5

Invalid entry, please enter a number between 1 and 4, inclusive: 3

The average temperature up to day 3 is: 2.50

Enter a number between 1 and 4 to see the average temperature for the entered number of days, enter a negative number to exit: 2

The average temperature up to day 2 is: 2.75

Enter a number between 1 and 4 to see the average temperature for the entered number of days, enter a negative number to exit: -1

Answer 1

This is what happens (read in the comments):

// THE CODE STARTS SHOWING THIS:
printf("\nPlease enter the number of days between 3 and 10, inclusive:\n");

// ...declarations...

// THEN THIS IS A DO ... WHILE, IT WILL RUN THE FIRST TIME WITHOUT CHEKING
// YOU HAVEN'T TAKEN USER INPUT YET
for (i = 0; i < days; i++) {
    // ON THE FIRST ITERATION i = 0
    do
    {
        // YOU HAVEN'T TAKEN USER INPUT YET
        // REMBEMBER THAT i = 0, SO i < 3 IS true
        if (i < 3 || i > 10) {
          // IT WILL SHOW THIS, BUT YOU HAVEN'T TAKEN USER INPUT YET
          printf("Invalid entry, please enter a number between 3 and 10, inclusive:");
        }
        // ... NOW YOU TAKE USER INPUT ...
    } while (i < 3 || i > 10);
}

---

I want to point out that the for loop you have will go from 0 to 3, but your low array only has 3 items since you declare it int low[3] , these items are low[0] , low[1] and low[2] . That means that the line scanf("%d", &low[i]); will point beyond the low array when i is greater than 2.

---

I'm unsure what you want, yet, here is some code to control the range of a variable:

int var;

do
{
    printf("\nEnter a value between 5 and 12:");
    scanf("%d", &var);
} while (var < 5 || var > 12);

Run Online

Here is a variant to show a message only when the input is incorrect:

int var;

for(;;)
{
    printf("\nEnter a value between 5 and 12:");
    scanf("%d", &var);
    if (var < 5 || var > 12)
    {
        printf("\nInvalid Input\n");
    }
    else
    {
        break;
    }
}

Run Online

I'd suggest to go line by line to understand how the code above works. In particular for(;;) will breate an infinite loop, the code will only leave it when it reaches break; . Note: you may also use continue; to skip to the next iteration of the loop, this is not used in the code above, but may come handy.