I have a struct which contains a member called char *text. After I've created an object from the struct, then how do I set text to a string?
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objects in C?, strings in C? I think you need to clarify your question a little bit more :)HyLian– HyLian2009-11-26 08:15:35 +00:00Commented Nov 26, 2009 at 8:15
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@HyLian: Objects in C? Yes, in C all data in storage is referred to as "objects". Strings in C? There are strings in C, of course.AnT stands with Russia– AnT stands with Russia2009-11-26 10:28:49 +00:00Commented Nov 26, 2009 at 10:28
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4 Answers
If your struct is like
struct phenom_struct {
char * text;
};
and you allocate it
struct phenom_struct * ps = malloc (sizeof (phenom_struct));
then after checking the value of ps is not NULL (zero), which means "failure", you can set text to a string like this:
ps->text = "This is a string";
Comments
typedef struct myStruct
{
char *text;
}*MyStruct;
int main()
{
int len = 50;
MyStruct s = (MyStruct)malloc(sizeof MyStruct);
s->text = (char*)malloc(len * sizeof char);
strcpy(s->text, "a string whose length is less than len");
}
Comments
Your struct member is not really a string, but a pointer. You can set the pointer to another string by
o.text = "Hello World";
But you must be careful, the string must live at least as long as the object. Using malloc as shown in the other answers is a possible way to do that. In many cases, it's more desirable to use a char array in the struct; i.e. instead of
struct foobar {
...
char *text;
}
use
struct foobar {
...
char text[MAXLEN];
}
which obviously requires you to know the maximum length of the string.
Comments
Example:
struct Foo {
char* text;
};
Foo f;
f.text = "something";
// or
f.text = strdup("something"); // create a copy
// use the f.text ...
free(f.text); // free the copy
answered Nov 26, 2009 at 8:18
Nick Dandoulakis
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