#include <reg51.h> #include <stdio.h> ........ lcd code ........ char putchar(char c) { lcd_rs = 1; //data lcd_rw = 0; //write lcd_en = 1; lcd_data = c; lcd_en = 0; if (!lcd_busy_check()) error_blink(); else return (c); } I get an error : Compiling... ..\8051_TRIAL_1\MAIN.C ..\8051_TRIAL_1\MAIN.C(92): Error: Type redefined: putch ..\8051_TRIAL_1\MAIN.C(92): Warning: Parameter declaration different: parameter 1 Complete I checked the header stdio.h, it has putchar defined as : #define putchar(c) putch(c) ... int putch(int); What can i do?