Is there any way to loop through a struct with elements of different types in C?

Question

my struct is some like this

typedef struct {   type1 thing;   type2 thing2;   ...   typeN thingN; } my_struct 

how to enumerate struct childrens in a loop such as while, or for?

Answer 1

I'm not sure what you want to achieve, but you can use X-Macros and have the preprocessor doing the iteration over all the fields of a structure:

//--- first describe the structure, the fields, their types and how to print them #define X_FIELDS \     X(int, field1, "%d") \     X(int, field2, "%d") \     X(char, field3, "%c") \     X(char *, field4, "%s")  //--- define the structure, the X macro will be expanded once per field typedef struct { #define X(type, name, format) type name;     X_FIELDS #undef X } mystruct;  void iterate(mystruct *aStruct) { //--- "iterate" over all the fields of the structure #define X(type, name, format) \          printf("mystruct.%s is "format"\n", #name, aStruct->name); X_FIELDS #undef X }  //--- demonstrate int main(int ac, char**av) {     mystruct a = { 0, 1, 'a', "hello"};     iterate(&a);     return 0; } 

This will print :

mystruct.field1 is 0 mystruct.field2 is 1 mystruct.field3 is a mystruct.field4 is hello 

You can also add the name of the function to be invoked in the X_FIELDS...