How to make a fifo in C?

I have to use mkfifo in my C program in Ubuntu. But I have an error when I compile: no such file or directory .

I think the problem because I have not set the panel_fifo environment variables. But I don’t khow how could I do this.

Here is my code I use to test this method:

char *myfifo="./sock/myfifo";

if (mkfifo(myfifo,0777)<0)
perror("can't make it");

if (fd=open(myfifo,O_WRONLY)<0)
 perror("can't open it");

I compile this with:

gcc gh.c -o gh

When I run, I get this error message:

can't make it:no such file or directory
can't open it:no such file or directory