#include <reg51.h>sbit IN1 = P1^0;sbit IN2 = P1^1;sbit IN3 = P1^2;sbit IN4 = P1^3;sbit IR1 = P2^0;sbit IR2 = P2^1;sbit IR3 = P2^2;sbit IR4 = P2^3;sbit IR5 = P2^4;void delay(unsigned int t) //延时函数{ unsigned int i,j; for(i=0;i<t;i++) for(j=0;j<120;j++);}void forward() //小车前进{ IN1 = 1; IN2 = 0; IN3 = 1; IN4 = 0;}void back() //小车后退{ IN1 = 0; IN2 = 1; IN3 = 0; IN4 = 1;}void left() //小车左转{ IN1 = 0; IN2 = 1; IN3 = 1; IN4 = 0;}void right() //小车右转{ IN1 = 1; IN2 = 0; IN3 = 0; IN4 = 1;}void stop() //小车停止{ IN1 = 0; IN2 = 0; IN3 = 0; IN4 = 0;}void main(){ while(1) { if(IR1==0&&IR2==1&&IR3==0&&IR4==1&&IR5==0) //小车直行 { forward(); } else if(IR1==0&&IR2==1&&IR3==1&&IR4==1&&IR5==0) //小车左偏 { left(); delay(500); } else if(IR1==0&&IR2==0&&IR3==1&&IR4==0&&IR5==0) //小车右偏 { right(); delay(500); } else if(IR1==0&&IR2==0&&IR3==1&&IR4==1&&IR5==0) //小车左转 { left(); delay(1000); } else if(IR1==0&&IR2==1&&IR3==1&&IR4==0&&IR5==0) //小车右转 { right(); delay(1000); } else //小车后退 { back(); delay(500); } }}优化上述代码

1. 在定义引脚时可以直接使用宏定义，避免了在代码中多次使用硬编码。
2. 将延时函数移动到头文件中，方便代码的复用和修改。
3. 使用switch语句代替多重if-else语句，代码更加清晰易读。

下面是优化后的代码：

#include <reg51.h>
#include "delay.h"

#define IN1 P1^0
#define IN2 P1^1
#define IN3 P1^2
#define IN4 P1^3
#define IR1 P2^0
#define IR2 P2^1
#define IR3 P2^2
#define IR4 P2^3
#define IR5 P2^4

void forward() {
    IN1 = 1;
    IN2 = 0;
    IN3 = 1;
    IN4 = 0;
}

void back() {
    IN1 = 0;
    IN2 = 1;
    IN3 = 0;
    IN4 = 1;
}

void left() {
    IN1 = 0;
    IN2 = 1;
    IN3 = 1;
    IN4 = 0;
}

void right() {
    IN1 = 1;
    IN2 = 0;
    IN3 = 0;
    IN4 = 1;
}

void stop() {
    IN1 = 0;
    IN2 = 0;
    IN3 = 0;
    IN4 = 0;
}

void main() {
    while(1) {
        switch((IR1<<4)|(IR2<<3)|(IR3<<2)|(IR4<<1)|IR5) {
            case 0b01010:  //小车直行
                forward();
                break;
            case 0b01110:  //小车左偏
                left();
                delay_ms(500);
                break;
            case 0b00100:  //小车右偏
                right();
                delay_ms(500);
                break;
            case 0b01100:  //小车左转
                left();
                delay_ms(1000);
                break;
            case 0b01001:  //小车右转
                right();
                delay_ms(1000);
                break;
            default:  //小车后退
                back();
                delay_ms(500);
                break;
        }
    }
}