size_t
A thing that I don't quite understand in C is the need for back and forth conversion between int and size_t. More often than not it seems rather unnecessary to me as you can just check and terminate beforehand, it is also quite rare that you get a negative int which would result in a large size_t due to the sign-bit. I also don't quite understand why many functions return signed integers when the output of those functions is most often used for allocation, at least in my observation.
I've run outThe functions ftell() and fseek() predate the addition of time atsize_t to the momentC programming standard, I may be ablethey have to add more laterremain backwards compatible to earlier versions of the language.
Reminder from previous review :
Convention When Using Memory Allocation in C
When using malloc(), calloc() or realloc() in C a common convention is to sizeof(*PTR) rather sizeof(PTR_TYPE), this make the code easier to maintain and less error prone, since less editing is required if the type of the pointer changes.
Example: from current code
buffer = calloc(bufLen, sizeof(*buffer));
Note that sizeof(char) has been replaced with sizeof(*buffer). This allows easy modification of the code, the allocation size will change if the type of buffer changes.
double H = .0f;
if (settingTime) {
H = 360 - (180 / PI) * acos(cosH);
} /* rising */
else {
H = (180 / PI) * acos(cosH);
} /* setting */
H = H / 15;
In the main() function this section of code could be a function that main calls:
int from;
if (sscanf(argv[3], "%i", &from) != 1) {
fprintf(stderr, "Expected an integer for the start date.\n");
}
int until;
if (sscanf(argv[4], "%i", &until) != 1) {
fprintf(stderr, "Expected an integer for the end date.\n");
}
if (0 == from || 0 == until) {
fprintf(stderr, "Start year or end year is invalid - start: %i end: %i\n", from, until);
return 0;
}
DRY Code
There is a programming principle called the Don't Repeat Yourself Principle sometimes referred to as DRY code. If you find yourself repeating the same code mutiple times it is better to encapsulate it in a function. If it is possible to loop through the code that can reduce repetition as well.
In the above section, the code from main() contains repetition, it might be better to turn this code:
int from;
if (sscanf(argv[3], "%i", &from) != 1) {
fprintf(stderr, "Expected an integer for the start date.\n");
}
into a function:
static int get_integer_arg(char* argv, char* usage)
{
int intVal;
if (sscanf(argv[3], "%i", &intVal) != 1) {
fprintf(stderr, "Expected an integer for the %s.\n", usage);
}
return intVal;
}
With this being the result:
int from = get_integer_arg(argv[3], "start date");
int until = get_integer_arg(argv[4], "end date");
if (0 == from || 0 == until) {
fprintf(stderr, "Start year or end year is invalid - start: %i end: %i\n", from, until);
return 0;
}
