linking error with : reads c compiler from rigel

I included cSio51.h for folowing functions : - putc (puts a character on screen) - getc (gets a character from input) - PrtDec (prints an intiger in decimal on screen) - printf (print a string of characters on screen) When i call one of these functions and compile the file, i get an linking error

Is there a replacement function for scanf (or to read a string)