编译错误-数值常数

Question

I keep getting the following compilation errors in my program. I'm suppose to write a program which uses the array p[] , which is passed to a function that calculates the polynomial of the nth degree (which is set to 5 below) and returns the value.

My errors are as follows:

poly.c:4:39: error: expected ';', ',' or ')' before numeric constant

poly.c:16:39: error: expected ';', ',' or ')' before numeric constant

My program:

#include <stdio.h>
#define N 5

double eval(double p[], double x, int N)

int main()
{
    double p[N+1] = {0,1,2,3,4};
    double x;
    printf("what value of x would you like?: ");
    scanf("%lf", &x);
    p[N+1] = eval(p[], x, n);
    printf("%lf", p[N+1]);
}

double eval(double p[], double x, int N)
{
    double y;
    y = x^(p[N+1]);
    return y;
}

Answer 1

After the preprocessor is done, your code looks like:

double eval(double p[], double x, int 5)

So there's still the missing ; at the end of that line, and that 5 makes no sense there.

Don't define such short macro names, and don't have formal parameter names that are also #define . Make sure you only use N in all your code where the global constant is meant.

Also, to pass the p array as a parameter, just say p , not p[] .

Answer 2

#define N 5

double eval(double p[], double x, int N)

Since you #defined N to be 5, the above will look like this after preprocessing:

double eval(double p[], double x, int 5)

Obviously that's wrong. Also function declarations need to be terminated with a semicolon.