C Question
C - strcpy() and char
I want to store a string to a char array inside a structure and when I access the char array I want the result to be displayed along with the value from the global variable errCode. When I access the errDesc member of the structure then I want the result to be "Error detected with error code 0xA0B0C0D0", but since using strcpy copies the string as it is I am getting a result "Error detected with error code %08lx" . Here is a sample code which replicates my issue:
int errCode = 0xA0B0C0D0;
void function(errpacket* ptr, int a, char* errString, ...);
typedef struct{
int err;
char errDesc;
}errpacket;
int main(){
errpacket* a;
void function(a, 10, "Error detected with error code %08lx", errCode);
return 0;
}
void function(errpacket* ptr, int a, char* errString, ...){
ptr->err = a;
strcpy(&ptr->errDesc, errString);
}
If my implementation is incorrect, please suggest me a way to do what I intend to. Also please point out the mistakes in the above code. I am new to coding so please bare with me...
Answer Source
try this fix:
#include <stdarg.h> //to be added for vsprintf use
int errCode = 0xA0B0C0D0;
void function(errpacket* ptr, int a, char* errString, ...);
typedef struct{
int err;
char *errDesc;
}errpacket;
int main(){
errpacket a; //you need allocate memory if you use a pointer here
void function(&a, 10, "Error detected with error code %08lx", errCode);
return 0;
}
void function(errpacket* ptr, int a, char* errString, ...){
ptr->err = a;
ptr->errDesc = malloc(strlen(errString)+1);
memset(ptr->errDesc, 0, strlen(errString)+1);
/*if(ptr->errDesc != NULL)
{
strcpy(ptr->errDesc, errString);
}*/
// use like following if you want use a formatted string
if(ptr->errDesc != NULL)
{
va_list args;
va_start (args, errString);
vsprintf (ptr->errDesc, errString, args);
va_end (args);
}
}