Suming ints

I am having trouble converting chars into ints:

Code:

char input[100];
int in, count, i;
while ((in = fgets(fp) != EOF){
    input[count] = in; 
    ++count;
}

int sum;
for(i=0,i < count; ++i){
  if (isdigit(input[i])){
   printf("&#37;c", input[i]); // this is ok, prints the actual number, if actual num is 1 then 1 is printed
   printf("%d", input[i]); // not ok, if actual num is 1, 49 is printed
   sum = 1 + input[i]  // if actual num is 1, sum should be 2
                                 // but it is 50
   printf("sum %d", sum);
}
}

What is the proper way of doing this ?

input[i] - '0' is the proper way.