#include <stdio.h>

#define TAX_RATE 12.50

int main(void)
{
 int quantity1;
 int quantity2;
 int quantity3;
 int quantity4;

 double totalprice1, totalprice2, totalprice3, totalprice4;
 double subtotal;
 double tax;
 double total;

 printf("How many AMERICANOs were sold?  ");
 scanf("%d", quantity1);

 printf("How many CAFFE LATTEs were sold?  ");
 scanf("%d", quantity2);

 printf("How many ESFRESSOs were sold?  ");
 scanf("%d", quantity3);

 printf("How many BANILLA LATTEs were sold?  ");
 scanf("%d", quantity4);

 totalprice1 = 3500 * quantity1;
 totalprice2 = 4000 * quantity2;
 totalprice3 = 4200 * quantity3;
 totalprice4 = 4500 * quantity4;
 subtotal = totalprice1 + totalprice2 + totalprice3 +totalprice4;
 tax = subtotal * TAX_RATE;
 total = subtotal + tax;

 printf("QTY\\tDEION\\tUNIT PRICE\\tTOTAL PRICE\\n");
 printf("---\\t-----------\\t----------\\t-----------\\n");
 printf("%+d\\tAMERICANO  \\t      3500\\t%+f        \\n", quantity1, totalprice1);
 printf("%+d\\tCAFFE LATTE\\t      4000\\t%+f        \\n", quantity2, totalprice2);
 printf("%+d\\tESFRESSO   \\t      4200\\t%+f        \\n", quantity3, totalprice3);
 printf("%+d\\tBANILLA LATTE         4500\\t%+f         \\n", quantity4, totalprice4);
 printf("   \\t           \\t          \\t-----------\\n");
 printf("   \\t           \\tSUBTOTAL  \\t%+f        \\n", subtotal);
 printf("   \\t           \\tTAX       \\t%+f        \\n", tax);
 printf("   \\t           \\tTOTAL     \\t%+f        \\n", total);

 return 0;
}

빌드 성공은 했는데

The variable \'quantity1\' is being used without being initialized

라는 메세지뜨면서 실행이 안되는데 quantity1 이 초기화되기 전에 사용했다니 이해가 잘 안가서요 부탁드립니다 ㅜ