How to debug this?

Karthik Agarwal

14y1.6k

Hi,

I am calling a function which is declared as follows:
typedef char HMI_CHAR;
typedef UINT32 LANG_SID_T;
HmLanguage1GetString(LANG_SID_T p_sid, HMI_CHAR * p_str_dest_P, UINT8 p_req_length, UINT8 p_cur_language_U8);

Now i am calling the above function as below:
HMI_CHAR *static_string;
UINT8 replace_char = 0;
HmLanguage1GetString(0xB4C, &static_string, 12, replace_char);

Actually i the API which i am calling will return a string in the static_string variable which is nothing but a destination pointer.
What i want to know is am i passing the parameters correctly?
And one more thing i want know is after getting the string which is returned by the API, how can i store the same in an array one character after the other?

Note: This is pure C coding. Reply needed ASAP.

4 Replies

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Vulpes14y ago
Accepted answer
What I said was that it's a char array already - the chars are stored one after the other in memory - and can be iterated one by one as follows:

while(!static_string[i])
printf("%c", static_string[i++]);
Sam Hobbs14y ago
Karthik, you really should spend some time learning the language. Any good book about C will explain that if you have a char * then you can access any char using [n]. The following works for me.
void HmLanguage1GetString(LANG_SID_T p_sid, HMI_CHAR * p_str_dest_P, UINT8 p_req_length, UINT8 p_cur_language_U8) {
p_str_dest_P[1] = '*';
}

int _tmain(int argc, _TCHAR* argv[])
{
HMI_CHAR static_string[256] = "initial";
UINT8 replace_char = 0;
puts(static_string);
HmLanguage1GetString(0xB4C, static_string, 12, replace_char);
puts(static_string);
}

Given the following:
char s[] = "Hello";

The following two lines are equivalent:
*(s+1) = '*';
s[1] = '*';

In any good book about C the first chapter about pointers will explain that and even most bad books about C will.
Karthik Agarwal14y ago
No Vulpes that API returns the whole string at once. Its not character by character what you said.
Vulpes14y ago
You're not in fact passing the parameters correctly because static string is already an HMI_CHAR * so you don't need to take its address.

Also, you need to initialize it to create a buffer big enough for the string that is going to be returned.

If, say, 256 bytes will be big enough, I'd suggest:

HMI_CHAR static_string[256];
UINT8 replace_char = 0;
HmLanguage1GetString(0xB4C, static_string, 12, replace_char);

static_string is (effectively) already a char array so you can index it to get each character. So to get the first one:

HMI_CHAR first = static_string[0];