指向数组的指针数组。在 PIC18 MPLAB IDE 中打印字符串

Question

我正在使用 MPLAB IDE 编写在 PIC 18 微控制器中使用的 C 代码。 我有 5 个字符串，我希望能够使用指针。 这个想法是拥有一个包含指向字符串数组的指针的数组。并将它们打印在控制台上。 下面的代码编译时没有错误或警告，但我在控制台上得到的都是垃圾。

有人能指出我正确的方向吗？非常感谢。 抱歉，如果我的代码格式不正确。

#include <stdio.h>
#include <p18f4520.h>
#include <stdlib.h> 
#pragma config WDT = OFF

#define size 64

#pragma romdata s1=0x300                        //specific ROM addresses for the data
  rom char *s1[] = "Hello";
#pragma romdata s2 = 0x307
  rom char *s2 = "Welcome to C programming";

#pragma romdata s3=0x31A
  rom char *s3= "My name is ";  

#pragma romdata s4=0x32C
  rom char *s4 = "Pic18 program";

#pragma romdata s5=0x33A
  rom char *s5 ="Goodbye, I hope this works!";


void printString(const char*);

void main (void) 
{   
    int i=0;

    char stringArray [] = {*s1, *s2, *s3, *s4, *s5};
    char *ptr=stringArray;


       while(i<5)
        {
             printString(&ptr[i]);
             i++;
          }
}

void printString( const char *strPtr)
{
   while(*strPtr !='\0')
     {
       printf("%c", strPtr);
       strPtr++;

      } 
}

`

Answer 1

嗯，这就是答案。

#include <stdio.h>
#include <p18f4520.h>
#include <stdlib.h> 
#include <string.h>
#pragma config WDT = OFF

#pragma romdata s1=0x300                      //specific ROM addresses for the data
 rom char s1[] = "Hello";
#pragma romdata s2 =0x307
   rom char s2[] = "Welcome to C programming";
#pragma romdata s3=0x41A
   rom char s3[] = "My name is";
#pragma romdata s4=0x32C
  rom char s4[] = "Pic18 program";
#pragma romdata s5=0x33A
   rom char s5[] ="Goodbye, I hope this works!";

void printAndCount(rom char *strPtr);
int j=0; int i=0;
void main (void)
{
    rom char* stringArray [] = {s1, s2, s3, s4, s5};
                    while(i<5 )
                {
                    printAndCount(stringArray[i]);  
                            i++;
                }
}
void printAndCount(rom char *strPtr)
    {   
    while (*strPtr != '\0' )
        {   printf("%c", *strPtr);
            strPtr++;
            ++j;    
                }
            printf("     %d\n",j);
            j=0;
}

Answer 2

问题是在您的代码中， stringArray 代表存储每个字符串的第一个字符的内存块，而不是它们的地址，请尝试以下操作：

void main (void) 
{   
    int i=0;

    char * stringArray [] = {s1, s2, s3, s4, s5};
    char **ptr=stringArray;


       while(i<5)
        {
             printString(*ptr[i]);
             i++;
          }
}

Answer 3

该代码中有几个基本错误。就用这个吧。

#include <stdio.h>
#include <p18f4520.h>
#include <stdlib.h> 
#pragma config WDT = OFF

#define size 64

// store ARRAYS here not pointers!
// Im not sure what non-standard "rom" means more exactly, 
// but these should be const in the C language
#pragma romdata s1=0x300                        //specific ROM addresses for the data
  rom const char s1[] = "Hello";                      
#pragma romdata s2 = 0x307
  rom const char s2[] = "Welcome to C programming";   

#pragma romdata s3=0x31A
  rom const char s3[] = "My name is ";                

#pragma romdata s4=0x32C
  rom const char s4[] = "Pic18 program";

#pragma romdata s5=0x33A
  rom const char s5[] ="Goodbye, I hope this works!";


void printString (const char* strPtr);

void main (void) 
{   
    int i=0;

    // this, however, must be an array of pointers (that point to the strings)
    // since the strings are const, the pointers must be declared pointer-to-const:
    const char* stringArray [] = {s1, s2, s3, s4, s5};

    while(i<5)
    {
         printString(stringArray[i]);  // now this syntax suddenly turned sane
         i++;
    }
}

void printString (const char *strPtr)
{
   while(*strPtr !='\0')
     {
       printf("%c", *strPtr);
       strPtr++;
      } 
}

Answer 4

试试这个：

#include <stdio.h>
#include <p18f4520.h>
#include <stdlib.h> 
#pragma config WDT = OFF

#pragma romdata s1=0x300                        //specific ROM addresses for the data
  rom char s1[] = "Hello";
#pragma romdata s2 = 0x307
  rom char s2[] = "Welcome to C programming";
#pragma romdata s3=0x31A
  rom char s3[] = "My name is ";  
#pragma romdata s4=0x32C
  rom char s4[] = "Pic18 program";
#pragma romdata s5=0x33A
  rom char s5[] ="Goodbye, I hope this works!";


void main (void) 
{   
    int i;
    char *stringArray [] = {s1, s2, s3, s4, s5};

    for (i = 0;  i < 5;  ++i)
    {
        printf("%s", stringArray[i]);
    }
}

它简化并进行了多项修复，修复问题最重要的是消除了 stringArray 中每个字符串名称之前的 *。其他更改是按惯例的 C 编码进行的。