How do I save a string of indefinite size to a structure?

Question

#include <stdio.h>
#include <stdlib.h>
#include <string.h>


struct Ecoponto{
   int codigo;
   int contentores[3];
   char cidade[20];
   char *rua;
   int nporta;
};


int main(int argc, char** argv) {

   struct Ecoponto ecoponto;
   printf("\nIntroduza o nome da rua:");
   scanf("%s",ecoponto.rua);
   printf("%s",&ecoponto.rua);



   return (EXIT_SUCCESS);
}

I wonder what is the best way to store "the name of the street" with an unknown size in the structure "Ecopoint Ecopoint".

Answer 1

To save a string of unknown size without spending extra memory, you need to read the street name in a buffer, a very large variable that can support any street name, for example, size 1000. Then use the string library. h and its strlen() function, which returns how many characters a string has and use strlen(buffer).

Now you know how many characters have the street name, if you do

char buffer[1000]; 
scanf("%s", buffer);
int a = strlen(buffer);

You can use the malloc() function of the stdlib. h library to store how much memory you need, for example:

char *nome_rua = (char *)malloc(sizeof(char)*a);

Then you can copy the contents of the buffer to your variable, and use the strcpy() function of the string library. h

Source: https://www.tutorialspoint.com/c_standard_library/string_h.htm

You need to malloc (a+1) positions, because the string must have O, which delimits its end.

And also, you can use the function

char *strncpy(char *dest, const char *src, size_t n)

Because then you would only copy from the buffer the amount of characters read.