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[\<- Notes 01/15](01-15.md)
---
# Structures Continued
- typedef can be used to give the structure an alias
- For example:
```
typedef struct info{
int number;
char character;
char string[10];
int array[10];
} INFO;
...
INFO real_info;
INFO *p;
```
- In the above example, struct info is called "INFO"
- The same can be done using a `#define` statement:
```
#define INFO struct info
...
struct info{
int number;
char character;
char string[10];
int array[10];
};
...
INFO real_info;
INFO *p;
```
- Initializing a struct in one line:
```
struct info{
int number;
char character;
char string[10];
int array[10];
};
struct info i1 = {99, 'Z', "abc", {0, 1, 2, 3, 4, 5, 6, 7, 8, 9}};
```
- Alternatively, you can set members one at a time:
```
struct info1, info2;
...
info1.number = 99;
info1.character = 'Z';
strcpy(info1.string, "abc");
for(i = 0; i < 10; i++){
info1.array[i] = i;
}
```
- You can also copy one structure to another very easily:
```
info2 = info1;
```
- Now I want to print each member of `i1`:
```
printf("%d\n", i1.number);
printf("%c\n", i1.character);
printf("%s\n", i1.string);
for(i = 0; i < 10; i++){
printf("%d\n", i1.array[i]);
}
```
- Arrays of structures can also be declared:
```
struct info lots_of_info[20];
lots_of_info[0].number = 17;
```
- Here is a struct in action:
```
struct simple{
int value1;
int value2;
}
int main(void){
struct simple s1 = {10, 15};
...
}
```
- Structures can be passed as an argument either as a "Call by Value" or "Call by Reference
- Example of "Call by Value":
```
void fun1(struct simple s){
s.value1++;
s.value2*=2;
}
```
- Example of "Call by Reference":
```
void fun1(struct simple *s){
s->value1++;
s->value2*=2;
}
```
- This is the same idea as passing variables as copies versus as pointers to memory
|
