Undefined Number of Contents in Array

I am trying to write a program in C to calculate the mean of a set of numbers. Of course, the number of values is up to the user, so I have a variable no_values that will get the number of values by scanf and an array values_x for variables and another values_f for frequency. I have scanned the chapter in my Programming in C book by Stephen Kochan but can't find this stuff. Here's the source code:

Code:

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#include <stdio.h>

int main () {
        printf("\n\nAn Application to find the mean of a set of numbers");

        int no_values, comp_values;

        printf("\n\nHow many values will you be entering? ");
        scanf("%i", &no_values);

        comp_values = no_values -1;
        int array_values;
        int values_x[array_values];
        int values_f[array_values];

        printf("\nPlease start entering your values");

        printf("|  x    |  f    |\n\n");

        for ( comp_values == 1; comp_values < no_values; ++comp_values ) {

                printf("x Variable: ");
                scanf("%i", &values_x[array_values]);

                printf("f Frequency: ");
                scanf("%i", &values_f[array_values]);

                printf("|%i    |%i    |\n\n", values_x, values_f);
        }
        return 0;
}

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It looks like you are trying to use variable length arrays, but array_values was not initialised.

Have you reached the point where the book talks about dynamically allocated arrays with malloc() and free()?

>for ( comp_values == 1;

you probably want

for ( comp_values = 1;

Code:

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int main () {
        printf("\n\nAn Application to find the mean of a set of numbers");

        int no_values, comp_values;

---

Note that declaring variables in the middle of blocks -- after, say, printf() statements -- is C99, not C89. You should probably avoid it if possible.

Then again, variable length arrays are C99 as well . . . .