#include<reg51.h>void delay();
void man(){
while(1) { p1=0x00; delay(); p1=0xff; delay(); }}void delay(){int i; for(i=0;i<500000;i++);}
And on what basis had you thought it should be defined?
Cx51 User's Guide: Error C202 (*** Error C202.) (keil.com)
A variable's type must be specified in a declaration before it can be used.
The parameters that a function uses must be specified in a declaration, or prototype before the function can be used.