i keep getting type-related errors

Question

I'm writing this program for my homework and i keep getting type errors. To my knowledge %d reads integer which is in this case the variable x and %lf reads double " variable f"

i've tried to remove "\n" in scanf() function as it was requested in other Questions

int x=0;
int l=0;
double f=0;
printf("Geben Sie eine ganze Zahl");
scanf("%d",x);
printf("Geben Sie eine reele Zahl");
scanf("%lf",f);
l=-1;
char r[1]="";
char s[1]="";
  while(l !=1){
    printf("Geben Sie ein Zeichen");
    scanf("%s",r);
    l=strlen(r);
}
return 0;

Errors:

C:/Users/---(9): warning in format string of scanf(): the conversion %d expects type int* but given type is int (argument 1).
C:/Users/---(11): warning in format string of scanf(): the conversion %lf expects type double* but given type is double (argument 1).

Answer 1

It's like the warning says: The function is expecting pointers to the types that you're giving it. Fix it by putting a & before the variable, which makes it pass the address instead:

printf("Geben Sie eine ganze Zahl");
scanf("%d", &x);
printf("Geben Sie eine reele Zahl");
scanf("%lf", &f);

There's also an issue with how you're reading in characters. This here

char r[1] = "";
char s[1] = "";

Makes two arrays that contain nothing else than a null terminator. It doesn't have any capacity to read in a non-empty string, which you're doing here:

scanf("%s", r);

It's unclear whether you're trying to read in a whole string or just a character, as your output implies. For just one character, your code should look like this:

char r;
scanf("%c", &r);

And for a whole string:

char r[20]; // can hold 19 chars plus a null terminator
scanf("%19s", r);

Adjust those sizes to match the length of the string that you need to read.