The following are the Standard Library Functions that come with the CodeVisionAVR Compiler.  In order to use these functions, the stdio.h file must included.

The lower level functions are:

    The getchar function returns a character received by the UART.
    The putchar function transmits a character using the UART.

The higher level functions use the lower level functions and are:

    The puts function outputs the null terminated character string, located in SRAM, followed by a new line character.
    The putsf function outputs the null terminated character string, located in FLASH, followed by a new line character.
    The printf function outputs formatted text according to the format specifiers in the string.  More on printf.
    The sprintf function is identical to printf except that the formatted text is placed in the null terminated character string.
    The gets function inputs the character string terminated by the new line character.
    The scanf function acquires formatted text according to the format specifiers in the string.  More on scanf.
    The sscanf function is identical to scanf except that the formatted text is located in SRAM.

The following are the actual function prototypes located in the stdio.h file.

    char getchar(void);
    void putchar(char c);
    void puts(char *str);
    void putsf(char flash *str);
    void printf(char flash *fmtstr);
    void sprintf(char *str, char flash *fmtstr);
    signed char scanf(char flash *fmtstr);
    signed char sscanf(char *str, char flash *fmtstr);
    char *gets(char *str,unsigned char len);

Note:  All information on this page was taken from the Help file of the CodeVisionAVR C Compiler.