When copying the code it gives an error using the WHILE function in C

Question

#include <stdio.h>
#include <string.h>
int main()
{
    int num_key=666;
    do
    {
        puts("\n\n\t*********************************************");
        puts("\t*                                           *");
        puts("\t*     Calculador de temperatura             *");
        puts("\t*                                           *");
        puts("\t*                                           *");
        puts("\t*                                           *");
        puts("\t*          DIGITE SUA SENHA                 *");
        puts("\t*                                           *");
        puts("\t*                                           *");
        puts("\t*                                           *");
        puts("\t*  DIGITE 0 PARA SAIR                       *");
        puts("\t*********************************************");
        scanf("%i",num_key);                    
    }while(num_key!=123);
}

I’m having a problem in that while loop, I can’t find the problem, it all comes running it from the bug and closes. I checked and redacted the logic twice.

Answer 1

An important tip is to enable all warnings displayed by the compiler.

See the warnings of your program:

See the first Warning, he’s saying he expected a int * instead of a int, as its variable num_key is not a pointer, so it is necessary to use the & to pass the address instead of the value to the function scanf(), so the compiler stops giving warnings.

The second Warning refers to the return of its function main. This function of yours is returning an integer, so it is necessary to assign the

return 0;

or

return 1;

in case of an error in your program, please note that the compiler also alerts you to this.

Your code:

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

int main(void)
{
    int num_key=666;
    do
    {
        puts("\n\n\t*********************************************");
        puts("\t*                                           *");
        puts("\t*     Calculador de temperatura             *");
        puts("\t*                                           *");
        puts("\t*                                           *");
        puts("\t*                                           *");
        puts("\t*          DIGITE SUA SENHA                 *");
        puts("\t*                                           *");
        puts("\t*                                           *");
        puts("\t*                                           *");
        puts("\t*  DIGITE 0 PARA SAIR                       *");
        puts("\t*********************************************");
        scanf("%i", &num_key);
    }while(num_key!=123);

    return 0;
}