C语言是什么意思

Question

我在KEIL uVISION3中运行程序时，显示如下错误？
Build target 'Target 1'
compiling OnelED.c...
canOnelED.c(1): warning C318: can't open file 'AT89X51.h'
ONELED.C(8): error C202: 'p1_0': undefined identifier
ONELED.C(10): error C202: 'p1_0': undefined identifier
Target not created
是什么意思，警告，和错误是什么意思？
谢谢大家，我问的是怎样解决这些问题。我的原程序如下
＃i nclude <AT89X51.h>
void main(void)
{
unsigned int a;
do
{
for (a=0; a<50000; a++);
P1_0 = 0;
for (a=0; a<50000; a++);
P1_0 = 1;
}
while(1);
}

Answer 1

既然你要解决问题，那我就不一一说错误原因了，有一点要注意，C语言是区分大小写的，P1_0和p1_0是不一样的。至于头文件，有时候我也根据自己的需要来添加代码，你复制我下面的代码到你工程下编译，看一下效果：

#include <AT89X51.h>
void main(void)
{
unsigned int a;
do
{
for (a=0; a<50000; a++);
P1_0 = 0;
for (a=0; a<50000; a++);
P1_0 = 1;
}
while(1);
}

另外我给你原始的AT89X51.h文件的代码：

#ifndef __AT89X51_H__
#define __AT89X51_H__

/*------------------------------------------------
Byte Registers
------------------------------------------------*/
sfr P0 = 0x80;
sfr SP = 0x81;
sfr DPL = 0x82;
sfr DPH = 0x83;
sfr PCON = 0x87;
sfr TCON = 0x88;
sfr TMOD = 0x89;
sfr TL0 = 0x8A;
sfr TL1 = 0x8B;
sfr TH0 = 0x8C;
sfr TH1 = 0x8D;
sfr P1 = 0x90;
sfr SCON = 0x98;
sfr SBUF = 0x99;
sfr P2 = 0xA0;
sfr IE = 0xA8;
sfr P3 = 0xB0;
sfr IP = 0xB8;
sfr PSW = 0xD0;
sfr ACC = 0xE0;
sfr B = 0xF0;

/*------------------------------------------------
P0 Bit Registers
------------------------------------------------*/
sbit P0_0 = 0x80;
sbit P0_1 = 0x81;
sbit P0_2 = 0x82;
sbit P0_3 = 0x83;
sbit P0_4 = 0x84;
sbit P0_5 = 0x85;
sbit P0_6 = 0x86;
sbit P0_7 = 0x87;

/*------------------------------------------------
PCON Bit Values
------------------------------------------------*/
#define IDL_ 0x01

#define STOP_ 0x02
#define PD_ 0x02 /* Alternate definition */

#define GF0_ 0x04
#define GF1_ 0x08

#define SMOD_ 0x80

/*------------------------------------------------
TCON Bit Registers
------------------------------------------------*/
sbit IT0 = 0x88;
sbit IE0 = 0x89;
sbit IT1 = 0x8A;
sbit IE1 = 0x8B;
sbit TR0 = 0x8C;
sbit TF0 = 0x8D;
sbit TR1 = 0x8E;
sbit TF1 = 0x8F;

/*------------------------------------------------
TMOD Bit Values
------------------------------------------------*/
#define T0_M0_ 0x01
#define T0_M1_ 0x02
#define T0_CT_ 0x04
#define T0_GATE_ 0x08
#define T1_M0_ 0x10
#define T1_M1_ 0x20
#define T1_CT_ 0x40
#define T1_GATE_ 0x80

#define T1_MASK_ 0xF0
#define T0_MASK_ 0x0F

/*------------------------------------------------
P1 Bit Registers
------------------------------------------------*/
sbit P1_0 = 0x90;
sbit P1_1 = 0x91;
sbit P1_2 = 0x92;
sbit P1_3 = 0x93;
sbit P1_4 = 0x94;
sbit P1_5 = 0x95;
sbit P1_6 = 0x96;
sbit P1_7 = 0x97;

/*------------------------------------------------
SCON Bit Registers
------------------------------------------------*/
sbit RI = 0x98;
sbit TI = 0x99;
sbit RB8 = 0x9A;
sbit TB8 = 0x9B;
sbit REN = 0x9C;
sbit SM2 = 0x9D;
sbit SM1 = 0x9E;
sbit SM0 = 0x9F;

/*------------------------------------------------
P2 Bit Registers
------------------------------------------------*/
sbit P2_0 = 0xA0;
sbit P2_1 = 0xA1;
sbit P2_2 = 0xA2;
sbit P2_3 = 0xA3;
sbit P2_4 = 0xA4;
sbit P2_5 = 0xA5;
sbit P2_6 = 0xA6;
sbit P2_7 = 0xA7;

/*------------------------------------------------
IE Bit Registers
------------------------------------------------*/
sbit EX0 = 0xA8; /* 1=Enable External interrupt 0 */
sbit ET0 = 0xA9; /* 1=Enable Timer 0 interrupt */
sbit EX1 = 0xAA; /* 1=Enable External interrupt 1 */
sbit ET1 = 0xAB; /* 1=Enable Timer 1 interrupt */
sbit ES = 0xAC; /* 1=Enable Serial port interrupt */
sbit ET2 = 0xAD; /* 1=Enable Timer 2 interrupt */

sbit EA = 0xAF; /* 0=Disable all interrupts */

/*------------------------------------------------
P3 Bit Registers (Mnemonics & Ports)
------------------------------------------------*/
sbit P3_0 = 0xB0;
sbit P3_1 = 0xB1;
sbit P3_2 = 0xB2;
sbit P3_3 = 0xB3;
sbit P3_4 = 0xB4;
sbit P3_5 = 0xB5;
sbit P3_6 = 0xB6;
sbit P3_7 = 0xB7;

sbit RXD = 0xB0; /* Serial data input */
sbit TXD = 0xB1; /* Serial data output */
sbit INT0 = 0xB2; /* External interrupt 0 */
sbit INT1 = 0xB3; /* External interrupt 1 */
sbit T0 = 0xB4; /* Timer 0 external input */
sbit T1 = 0xB5; /* Timer 1 external input */
sbit WR = 0xB6; /* External data memory write strobe */
sbit RD = 0xB7; /* External data memory read strobe */

/*------------------------------------------------
IP Bit Registers
------------------------------------------------*/
sbit PX0 = 0xB8;
sbit PT0 = 0xB9;
sbit PX1 = 0xBA;
sbit PT1 = 0xBB;
sbit PS = 0xBC;
sbit PT2 = 0xBD;

/*------------------------------------------------
PSW Bit Registers
------------------------------------------------*/
sbit P = 0xD0;
sbit FL = 0xD1;
sbit OV = 0xD2;
sbit RS0 = 0xD3;
sbit RS1 = 0xD4;
sbit F0 = 0xD5;
sbit AC = 0xD6;
sbit CY = 0xD7;

/*------------------------------------------------
Interrupt Vectors:
Interrupt Address = (Number * 8) + 3
------------------------------------------------*/
#define IE0_VECTOR 0 /* 0x03 External Interrupt 0 */
#define TF0_VECTOR 1 /* 0x0B Timer 0 */
#define IE1_VECTOR 2 /* 0x13 External Interrupt 1 */
#define TF1_VECTOR 3 /* 0x1B Timer 1 */
#define SIO_VECTOR 4 /* 0x23 Serial port */

#endif

Answer 2

Build target 'Target 1'
正在创建Target 1
c(1): warning C318: can't open file 'AT89X51.h'
意思是第一行找不到'AT89X51.h' 库文件
C(8): error C202: 'p1_0': undefined identifier
意思是第8行p1_0没有定义。
C(10): error C202: 'p1_0': undefined identifier
意思是第10行p1_0没有定义。

补充：
＃i nclude <AT89X51.h> //你这里用了中文＃，改成英文#，如果出错上面第一行的错误，那么库文件夹里没有AT89X51.h，要去创建它。
void main(void)
{
unsigned long a,p1_0,p2_0;//p1_0,p2_0要定义。 还要改成long，因为数量大。
do
{
for (a=0; a<50000; a++);
P1_0 = 0;
for (a=0; a<50000; a++);
P1_0 = 1;
}
while(1);
}

Answer 3

Answer 4

p1_0变量没有定义，可能是因为头文件AT89X51.h没包括进来