warning C291: not every exit path returns a value

ID:1061638 · 發(fā)表于 2023-1-28 23:31

我這個(gè)是矩陣按鍵
#include "reg52.h"
typedef unsigned char u16;
typedef unsigned  int u8;
#define KEY_MATRIX_PORT  P1//定義矩陣p1
#define SMG_A_DP_PORT  P0//定義數(shù)碼管腳
u16 gsmg_code[17]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,
0x7f,0x6f,0x77,0x7c,0x39,0x5e,0x79,0x71};//共陰0到f
void delay_10us(u8 ten_us)
{
      while (ten_us--);
}
u16 key_matrix_scan(void)
{
  u16 key_vary=0;
  KEY_MATRIX_PORT=0x7f;//第一列為低電平
  if(KEY_MATRIX_PORT!=0x7f)//如果第一列的數(shù)不為0x7f,證明有按鍵按下
{
   delay_10us(1000);//延時(shí)1s
switch (KEY_MATRIX_PORT)
{
                                       case 0x77:key_vary=1;break;
                                       case 0xb7:key_vary=5;break;
                                       case 0xd7:key_vary=9;break;
                                       case 0xe7:key_vary=13;break;
   }
}
while (KEY_MATRIX_PORT!=0x7f)//等待按鍵按下

KEY_MATRIX_PORT=0xfb;//第二列為低電平
  if(KEY_MATRIX_PORT!=0xfb)//如果第一列的數(shù)不為0xfb,證明有按鍵按下
{
   delay_10us(1000);
//延時(shí)1s
switch (KEY_MATRIX_PORT)
{
                                       case 0x7b:key_vary=2;break;
                                       case 0xbb:key_vary=6;break;
                                       case 0xdb:key_vary=10;break;
                                       case 0xeb:key_vary=14;break;
   }
}
while (KEY_MATRIX_PORT!=0xfb)

KEY_MATRIX_PORT=0xfd;//第三列為低電平
  if(KEY_MATRIX_PORT!=0xfd)//如果第一列的數(shù)不為0x7f,證明有按鍵按下
{
   delay_10us(1000);//延時(shí)1s
switch (KEY_MATRIX_PORT)
{
                                       case 0x7d:key_vary=3;break;
                                       case 0xbd:key_vary=7;break;
                                       case 0xdd:key_vary=11;break;
                                       case 0xed:key_vary=15;break;
   }
}
while (KEY_MATRIX_PORT!=0xfd)

KEY_MATRIX_PORT=0xfe;//第四列為低電平
  if(KEY_MATRIX_PORT!=0xfe)//如果第一列的數(shù)不為0xfe,證明有按鍵按下
{
   delay_10us(1000);//延時(shí)1s
switch (KEY_MATRIX_PORT)
{
                                       case 0x7e:key_vary=4;break;
                                       case 0xbe:key_vary=8;break;
                                       case 0xde:key_vary=12;break;
                                       case 0xee:key_vary=16;break;
   }
}
while (KEY_MATRIX_PORT!=0xfe)

return key_vary;
  }

void main()
{
u16 key=0;

      while(1)
      {  key=key_matrix_scan;
   if (key!=0)
   SMG_A_DP_PORT= gsmg_code[key-1];

      }

}
報(bào)錯(cuò)
compiling juzhenshianjian.c...
juzhenshianjian.c(76): warning C291: not every exit path returns a value
juzhenshianjian.c - 0 Error(s), 1 Warning(s).