Question

When I try to compile this, it says “testrand.c:(.text+0x11): undefined reference to `rand_number'”

1 #include <stdio.h>
2 #include <time.h>
3 
4 int rand_number(int param);
5 
6 main()
7 {
8 while(5)
9 {
10         printf("%d", rand_number(15));
11         sleep(1);
12 }       
13 
14 
15 int rand_number(int param)
16  {
17   srand((unsigned int)time(NULL));
18     int x = param;
19     int rn = rand() % x;
20         return rn;
21 }       
22 }

But, I’ve clearly defined it up there…

I have tried including time.h in quotation marks, including stdlib.h, etc… but still have no idea what’s going on. Anyone know what’s happening?

Answer 1

This happened because your rand_number function is defined within other function, main.

This should fix your problem:

#include <stdio.h>
#include <time.h>

int rand_number(int param);

main()
{
    while(5)
    {
        printf("%d", rand_number(15));
        sleep(1);
    }
}

int rand_number(int param)
{
    srand((unsigned int)time(NULL));
    int x = param;
    int rn = rand() % x;
    return rn;
}