分配值并将结构作为参数传递

Question

• To asign a char value into the struct 'field', I have to use strcpy ?

I tried this:

struct student{

   char name[50];
   int  age;
};  


int main(){

struct student std;

std.name = "john";  //Doesnt work
strcpy(std.name, "john");  //It DOES work
std.age = 20;

return 0;}  

Why when comes to char I can not simply use the ' = ' to assign a value ?

• How may I pass a struct initialized in main(){} as a parameter to a function and change it's values inside the function without the need of a return. Do I just use the '*' like:

    void MyFunction(struct student *std){ std->Name = "John"; std->Age = 20; } int main(){ struct student me; Myfunction(me); } 

Is that the correct way to do so ?

Answer 1

No matter which way you pass the struct (by value or by pointer), you cannot directly assign a string literal to a char array. You can only use strcpy or strncpy or something else that copies the characters one by one.

But there is a workaround, you can directly assign struct to another one. C compiler will perform a bitwise copy of the struct.

struct student s1;
strcpy(s1.name, "john");
s1.age = 10;
struct student s2;
s2 = s1; // now s2 is exactly same as s1.

Attach an example of use pointer to pass struct:

void handle_student(struct student *p) { ... }
int main() {
  struct student s1;
  handle_student(&s1);
}

Answer 2

This is just an additional information

While declaring the structure variable, it can be initialized as below.

int main(){
    struct student s1 = {"John", 21};
     //or
   struct student s = {.name= "John" };

}