Code:
int a[SIZE];
int i;
int x;
int j;
int flag;
int idx=0;
printf("Enter 20 numbers between 10 and 100\n");
scanf("%d",&a[i]);
&a[i] is telling scanf to place the input at the address of the 'i'th term in the 'a' array. Again, you have not supplied a value for i...so it doesn't know what part of the array you want to use. Try:
Code:
int a[SIZE];
int i;
int x;
int j;
int flag;
int idx=0;
printf("Enter 20 numbers between 10 and 100\n");
scanf("%d",&a[0]);
//this is how to accept multiple numbers
//i = 1 because a[0] has already been filled
for (i = 1; i < 20;i++){