undefined reference to gcvt

   #include <stdlib.h>
   #include <string.h>



    int main(){

    float x = 123.457; 

    char buf[100];

    gcvt(x, 6, buf); 

    printf("buffer is: %s\n", buf);


   return 0; 

}

I have undefined reference to gcvt despide I added the stdlib.h. I am very blocked. Thanks a lot for you help