I'm struggling with scanf with float - c

Question

I am having some issues with the scanf function.
I am trying to printf a scanf result, but it only returns 0.00000
Can someone help me? Here is my code done so far:
#include <stdio.h>
int main() {
float grade;
char choise;
do {
printf ("Type your grade: ");
scanf("%f", &grade);
printf("Want to continue? s/n: ");
scanf(" %c", &choise);
printf("%s \n", &choise);
printf("%f", &grade);
}while(choise != 'n');
}

Answer 1

printf("%f", &grade); is wrong
try
printf("%f", grade);
But there are many other issues. At the very least, you must check the values returned by scanf, and you should use int main(void) or int main(int argc, char **argv). eg:
#include <stdio.h>
#include <stdlib.h>
int
main(void)
{
float grade;
char choise;
do {
printf("Type your grade: ");
fflush(stdout);
if( scanf("%f", &grade) != 1 ){
fprintf(stderr, "Invalid input\n");
exit(1);
}
printf("Want to continue? s/n: ");
fflush(stdout);
if( scanf(" %c", &choise) != 1 ){
fprintf(stderr, "Invalid input\n");
exit(1);
}
printf("%c\n", choise);
printf("%f\n", grade);
} while( choise != 'n' );
return 0;
}
If you don't check the value returned by scanf, you don't know if any data was written into the variable. Since neither choise nor grade is initialized, attempting to read those values if scanf did not assign to them is undefined behavior. The behavior is also undefined if the input stream contains a value that cannot be represented as a float (eg, if it is a value greater than FLT_MAX), but that's really just an argument for avoiding scanf rather than a suggestion to try to make scanf usable. You can try to use scanf to make a user friendly interface, but it's really not worth the effort. Much better to simply abort on bad input. (If you want a user friendly interface, I would recommend you are using the wrong language.) See http://sekrit.de/webdocs/c/beginners-guide-away-from-scanf.html for more details on why you really ought to just avoid scanf completely.

Answer 2

These calls of printf
printf("%s \n", &choise);
printf("%f", &grade);
are incorrect.
In the first call you are trying to output a single character as a string. In the second call you are trying to output a pointer of the type float * as an object of the type float.
Instead you have to write
printf("%c\n", choise);
printf("%f\n", grade);

Answer 3

The lines
printf("%s \n", &choise);
printf("%f", &grade);
are wrong.
They should be
printf("%c \n", choise);
printf("%f", grade);
The %s format specifier should only be used for strings (null-terminated sequences of characters), not individual characters. The expression &choice does not point to a string, as the character sequence is not null-terminated.
Also, the %c and %f format specifiers require values, not addresses, when using them with printf. Only when using them with scanf should you pass an address.